Pop-Off/Blow-Off valve 101

[WheelerDealer]

Can any of y'all that have pop-offs post pictures of them inside and out? I am wanting to learn more about them as far as who all makes or made them, which ones are manual, which are automatic or both manual and automatic. On the automatic ones, how are they triggered, RPM switch, pressure triggers and so on. I would love to hear what you guys that have them and have run them have to say about the different options and styles of valves,and who you think made the best one and why. I would also like to see some good pictures of valves both on and off the pump if y'all have them. Also, do any of y'all run them on double duty lake/race boats like mine will be, and if so do you disable it while at the lake, or just set it up to be manually fired when at the lake/river?
I will be running one of HTP's Jet-A-Ways on my boat and might also run a pop-off when we go to the track if we step up into some bigger numbers from where we hope to start.
Anybody got one for sale????

[Squirtin Thunder]

I will say that for some strange reason Willis kept popping the pop-off valve off the pump at Ming in Sept. So what ever one you chose to go with it will in my eyes need a better bolting system to hold it in place plus a special restrieghnt sytem. It doesn't take much for a restrieghnt system as Willis proved by using a small ratchet strap. But there is one, to my knowlage in Lake Ming.
Jim

[UBFJ #454]

WheelerDealer -
We're running both Duane's Jet-A-Way and Dan Nelson's PopOff (Jett Performance Marine here in Phoenix) ... In my opinion, as humble as it never is, is that each is the Best Device of their type made to date. Unfortunately, Dan no longer makes his design and used ones are hard to find ... If you can find one at a reasonable price, I'd suggest you get one ... Again I think they are the Best Made.
Our PopOff is set up to be 'Triggered' both Manually (by a button on the steering wheel Right Next To The Driver's Thumb ... He doesn't have to reach for it) and Automatically in case of Severe Intake OverCharge (set off by a pressure sensor installed midway up the suction piece ... There is a analog/digital box hooked to the actual PopOff that is used to set the psi you want it to go off automatically ... psi is converted to an electrical signal which actually actuates the silinoid) ... That is the way Dan Designed It To Be Used, and Only In That Way.
I might comment that PopOff's were Designed To Be & Are Racing Devices and as such are a High Maintainence Item ... We check our's throughly after Every Run and Totally Disassemble It & Clean It Throughly after Every Race Replacing Retaining Bolts, Bumper Rubbers, etc., as required ... Sometimes we do this during a race, if it doesn't seem to be working just right. I personally think that most of the popoffs, 'Popping Off/Apart' are a result of either poor maintainence (not paying extreme detail to the unit) and/or modifications done to the unit by those other than the original manufacturer ... but, that's just my take on it.
One thing I feel very strongly about is that I think any boat running faster than 9 seconds & say 110/115 mph (certainly 120 and above) should be Required to have Both a rachet type device (like a Jet-A-Way) and a PopOff Installed & Functioning Properly ... Each device does something different and addresses different circumstances that likely occur in the Race Environment.
Realize what I've said above only pertains to Nelson's unit as that is the only one I've used to date ... and, will continue to use unless forced to find another unit due to lack of availability of replacement parts ... Something I don't think we'll be faced with in the near future. Wheeler, if you do manage to find a used Nelson unit, PM me and I'll fill you in on some other things about the unit, refurbishing it (if required) and its maintainence.

[ARS Marine inc.east]

Should Be Able to post some Pics For ya later tomorrow,
Battrey is Dead In the Camera, Need to buy a new one!
Everything Takes a Chit after Christmas
We carry a Miersch Popoff
Along with the NEW Saftey Restreint Bag that is made to Fit.
The Kit comes complete with, Co2 tank, lines,Regulator and Popoff,
The NEW Saftey Rastreint Bag Sell's for only $100.00
Thats alot Cheaper than Purchasing a New Popoff, That goes to the Bottom of the Lake Or River!

[UBFJ #454]

Restraint Bag???

[bp]

Restraint Bag???
yeah, they sewed a little baggy together that straps the miersch on so it won't fly 100' in the air when the bolts break. tom cress was wearing one at the last race - kinda cute :D. won't work with yours though. the miersch doesn't have the valve popping way up like dan's does. the door just opens.

[UBFJ #454]

Seems to me replacing the restraint bolts after every race, or during if needed, would make more sense (and be far cheeper ... our SS Bolts cost $1.86 ea., w/Tax) than putting a 'Junk Bag' over the PopOff. A guy spends $1,500 to $2,000 + Dollars for a PopOff, then has to spend another $100 Bucks to make sure he doesn't Blow it Shy High and lose into the drink ... Get Real ... Better Yet, Get a PopOff Designed and Manufactured To WithStand The PSI's Involved ... Then Maintain It Properly.
I know Willis' PopOff was a Miersch and the first time it came ajar (but stayed with the boat) he broke a retainer eye bolt on one side because he asked me if we had one ... When he 'Launched It', the PopOff, into Ming his next run he had run into town and gone to either Ace Hardware or Home Depot for a replacement bolt ... what kind or grade he got I have no idea. I do know that the eye bolt he showed me and wanted a replacement for didn't look like it could restrain much of anything much less hold a PopOff onto a suction piece.
Jerry Hick's PopOff that he 'Launched' into Ming is a different story. His was a Modified Jett Performance Design Unit (Not Modified by Dan Nelson ... Could well have had to be as I understand it was purchased used and the previous owner(s) had reworked it in some unknown manner) ... it had somewhat larger retaining rods down its sides with a different retainer collar that had counter sunk (flanged) #8 grade bolts connecting the collar to the rods. It's interesting that the Saturday evening before Jerry Launched the Guts of his PopOff into Ming he and I were talking about the Nelson Unit and I related to him our maintainence procedures and what I watched for to go bad ... His comment to me was basically he hadn't had any of those kinds of problems and didn't see the need to do what we do ..... Next morning, First UBFJ Run ... He Launched It just after going thru the traps ... Bye the Bye, on that run he got the 1st Leg of his new UBFJ Record ... a 7.56 ... Backed up in the Finals by a 7.53 (The New Record & w/out using any n2o ... Didn't have a bottle in the Boat ... '"Hot Tub" is One Dialed In, FAST Boat And Jerry Is One Heck Of A Driver, Perhaps The Best Jet Drag Boat Driver Driving Today).
Now I'm not going to say that we won't Launch Ours ... Cause, God Forbid, It Could Happen ... But ... With regards to PopOffs, I will Sat Maintainence, Maintainence, MAINTAINENCE, ..................... !!!

[WheelerDealer]

Hi Bear,
BEAR_454PE originally posted...
Seems to me replacing the restraint bolts after every race, or during if needed, would make more sense (and be far cheeper ... our SS Bolts cost $1.86 ea., w/Tax) than putting a 'Junk Bag' over the PopOff.
I kinda agree with you here Bear. I certainly agree with your maintaining of the valve or any other pieces of equipment that could cost or save you your drivers life and I don't think what you do is overkill at all, I do however think it makes perfect sense to put a restraining device of some sort on that high dollar much needed piece of equipment that is hanging back there where it is sure to be lost without one if something happens...Murphy's Law ya know!
Thanks for the replys guys. Pictures please if you have them.

[Unchained]

In this blowoff valve 101 discussion what hasn't been addressed is the that the currently available popoffs have a terribly unreliable track record.
I've seen them launch many times,
Go off at 1/2 track many times,
And fail to go off at all.
And then coming up with a restaint bag to catch the parts as they fly off ?
I have the highest respect for Jak and his maintenance program that has seemed to work for them but to me anything that requires that high of maintenance attention is just a bad design to begin with.
I talked to a racer who has run in the high 7s with his boat and his take on the popoffs was " we have one because the rules require it, but I have no confidence whether it will work or not"
I could use some kind of pressure relief setup for my boat but I won't invest 2k into something that is that crude and unreliable.
Also the popoff that most are using is only something that was just BOLTED on the only available hole rather than engineering what was required to do the job even iif it required additional welding or machining on the pump body.

[promod]

think we need to get duane at htp to come up witha new design of the popoff like the jetaway and let them work together i believe duane could come up witha good popoff

[UBFJ #454]

Mark -
I couldn't agree more with you ... The PopOffs Currently Being Manufactured and Sold Are Not Really Useful For The General Boating Public ... There needs to be a new design thought out and built for use on recreational boats. One capability that such a device should have is the ability to be 'ReSet' after having been 'Triggered' ... Currently most Race Devices remain open once set off and have to be manually reset upon the boats return to the shore ... Not reasonable for recreational boats.
As you point out, the integration of a 'Flow Diversion' feature into a new suction piece design would be most useful and probably not all that hard to design and build.
Hope you and yours had a Very Merry Christmas and All Have A Very Safe & Happy New Year.
Jak

[cyclone]

I need to buy a pop off for this season. Can you guys give me contact info and ball park pricing on what's still available? names, addresses, phone numbers and websites would be real helpful.

[Cs19]

I think the Miersch is your only option if you go new Mike.
I see that Brule's valve is one of the few that does not go off at half track every pass.Has he removed the inlet press. "trigger" deal on it?

[cyclone]

dont know if he's modified his or not. I know he uses it at the end of every pass to slow the boat down safely though.

[Unchained]

I've got my own ideas on how it should be done.
It WILL involve additional welding and machining.
It will use off the shelf valves that are cheap,easy to replace, and have a proven industrial use record.
I think it should regulate the intake water pressure rather than dump it like an on/off switch.
Then resetting would never be an issue and the depth of the shoe would be less critical.
I can hear it now ...........
If ____________ didn't build it then how could it possibly work.

[superdave013]

I can hear it now ...........
If ____________ didn't build it then how could it possibly work.
C'Mon, fill in the blank! lol

[Unchained]

I'm going.....................
http://www.saunalahti.fi/frog1/wavs/boldly.wav

[Cs19]

I think it should regulate the intake water pressure rather than dump it like an on/off switch.
You saying have it "blow off " when it hits a certain psi, and then have it close while still on the throttle?
How about using the spring loaded one? If you get the correct springs in it, it should work like that.The pressure will overcome the springs and bleed of some press. and then close after the psi falls.
Wheres Brule anyways?

[cyclone]

I'm none too excited about spending 2g's on a popoff. I'm all about safety, but god there has got to be a better and hopefully cheaper way to accomplish the same goal. Perhaps Unchained has the answer?
I wouldn't be against fabbing or cutting up a suction housing to try it....

[Duane HTP]

Funny you would mention it, Promod. I do have plans drawn up for a totally new type of suction pressure relief valve. I would like to produce some and test them, but I just don't have that kind of money to spend when there is such a limited market. I just don't think I could ever recover my R & D expense on the project. What to do?????????????

[Willis]

Dec. 30, 2004
Hello every one,
Just wanted to say to my knowledge, Like Ming has several out there.
:jawdrop:
Jerry Hicks was the last victim to loose his. :umm:
The company who made mine is Professional Performance Products, Fallbrook, CA 92028 – 760 728-3934 Roy Miersch.
The 1st product he made that I lost in the lake was from over tightening the hold down screws used on hand hole cover on the jet.
Tom Papp, Jim Brock both gave me some larger diameter screws to hold down the “POP-OFF”.
The pop off works fine if you stay on top of the plastic hose ends in the fittings. The main reason why the pop off engages premature is that the system looses air pressure because the hose ends are not pushed in the fittings or cut square and air loss occurs valve open- - - :2purples:
The system was designed to open when the water pressure on the intake side becomes greater than the air keeping it closed.
My data recorder has psi reading up to 82 psi on the slow down side and 36-54 psi during the run. Hence, I set my psi to keep it closed at 80-85 psi. You can put too much psi to keep it closed and it won’t open!
:argue:
:messedup:
I use to think the $$$$ to purchase it was a bit high, until I had to use it.
Willis

[LVjetboy]

"The 1st product he made that I lost in the lake was from over tightening the hold down screws used on hand hole cover on the jet."
Or was it a design defect?
"Jim Brock both gave me some larger diameter screws to hold down the “POP-OFF”
Why not recommended standard?
"The pop off works fine if you stay on top of the plastic hose ends in the fittings. The main reason why the pop off engages premature is that the system looses air pressure because the hose ends are not pushed in the fittings or cut square and air loss occurs valve open"
Plastic hoses? If pressure critical, I'm thinking why not a secure connection not subject to small installation errors? Is this not an important safety item...life critical? As others have posted...dumb design. At the least not mature and badly needing refinement.
jer

[Willis]

LVJetboy,
I do not think this is a safety issue. Like all drag racing equipment, you have too maintain them properly.
:argue:
Jak said it the best, they remove their pop off and take it apart to service after every race to make sure it works properly.
Willis

[victorfb]

i see that Roy Miersch lives here in fallbrook. (its a small town) so ill give him a call after the new year and see if he will enlighten me on his design. maybe we can come up with something.

[Cs19]

http://www.schoutenranch.com/boat/lb2/images/MVC-014S.jpg
http://www.***boat.com/image_center/data/521/409Dcp00472-med.jpg

[bp]

"The 1st product he made that I lost in the lake was from over tightening the hold down screws used on hand hole cover on the jet."
Or was it a design defect?
"Jim Brock both gave me some larger diameter screws to hold down the “POP-OFF”
Why not recommended standard?
"The pop off works fine if you stay on top of the plastic hose ends in the fittings. The main reason why the pop off engages premature is that the system looses air pressure because the hose ends are not pushed in the fittings or cut square and air loss occurs valve open"
Plastic hoses? If pressure critical, I'm thinking why not a secure connection not subject to small installation errors? Is this not an important safety item...life critical? As others have posted...dumb design. At the least not mature and badly needing refinement.
jer
plastic tubing rated at pressures well above 100psi. and you need to be very precise in how you go about preparing the tube ends. in a very real sense, it's fail safe, because if any part of it fails, the valve fails open.
i disagree with your dumb design, immature, badly needing refinement conclusion, since you haven't even even spent two seconds looking at the device and the controls, let alone disected it to come to this rather ignorant short sighted conclusion. i'm not saying it's perfect, but it's a very long way from dumb. the miersch valve works very well when it's set up correctly, and does not require significant amounts of pm. but the setup is precise.

[Willis]

Hello every one,
:jawdrop:
I found this black hose at Lowes, Home Depot, an other hardware stores. It also came in clear!
This is not the hose to use! The psi ratting is too low and the intended use is not for 150 - 250 psi systems.
:messedup:
The correct hosing is found at Hydraulic pump and air breaks supplies. Be sure it’s rated at 250 psi minimum.
Willis

[Aluminum Squirt]

What happened to the "101" portion of this thread? I think I sort of understand the blow off valve, its for sudden shut downs, aka high pressure on the intake side, right? I think I also understand the jet-a-way a little, keeping the impeller turning in case of a catastrophic engine failure, but I don't understand how they would work together or if one is better than the other. Is it common to use both? Are they required when under a certain ET or over a certain MPH? We don't have anything like this in the white water world. Can somebody dumb it down a little so I can understand please? Thanx-Aluminum Squirt

[LVjetboy]

"you need to be very precise in how you go about preparing the tube ends. in a very real sense, it's fail safe"
I'll back off on my safety comment but not the dumb design. Ok, sure it works to a degree. But if plastic lines need to be so precise (some apparently posting the result of not so precise) why not a more secure connection? I had cheap plastic lines leak on a PD, so I switched to hydraulic lines...no more leaks. A PD is not as critical as pressure relief in my opinion. So if a perfectly cut pastic hose ending is so critical to compression fitting seal on intake relief, what's the point?
Is a more secure connection too much to ask for a system that is race critical? To me a design that requires very precise end tube preparation when an alternative (although a bit more expensive) does not, is a dumb design. ESPECIALLY when that design services racers who typically spend more money to get things right and run higher critical speeds than your average joe lake jetter. And those racer's day or entire year could be ruined by a slightly leaking freakin' plastic tube connection? Under-designed or maybe even poorly designed for the application and target audience don't you think?
"i disagree with your dumb design, immature, badly needing refinement conclusion, since you haven't even even spent two seconds looking at the device and the controls, let alone disected it to come to this rather ignorant short sighted conclusion."
You're right. I haven't looked at the controls or dissected. Controls and function different issues? My comments about design based on those who've posted and the problems they've had. And I don't have the experience with the design you've have. Still I post what I think and everyone's free to decide. What I say could be total BS.
So....are my conclusions really so short-sighted?
Or is this design in need of an overhaul?
jer

[LVjetboy]

"Can somebody dumb it down a little so I can understand please?"
Not dumbing down but application?
How often do you worry about engine failure at 100+ mph and hooking in smooth water? If you do then a ratchet and/or blowoff may help straight line recovery depending on intake and hull design.
If you don't then who cares? With all the yanks & banks typical of white water speed...inadvertant shutdown may not be a tunnel hull issue. Although it may be a survival issue.
jer

[Unchained]

I need some information from someone who has a blow off valve to get some water flow comparisons from the current units.
In the open position what is the square in. of area that the water flows through?
In other words, how far does the valve lift vertically to uncover the 4" hand hole?
Also from a datalog of the intake water pressure after the popoff was tripped,
does the pressure drop right to 0 or is there still some pressure?
Does the popoff need to bypass enough pressure to drop the pressure to 0 or does it only need to bypass enough to get the intake pressure down to 20 lbs or so ?
It will be easier to bypass just enough water to get the pressure down for a safe shutdown then dumping everything.

[billet racing]

I run Roy's pop off. Had to make some minor adjustments. The first big problem was bending/breaking the bolts. Typical run has 40-45 lbs intake pressure, and 80+ at shutdown. Set the pressure at 85 and she blows at shutdown, and then resets after I've slowed down considerably.
Prior to the popoff, I had blown out two hand hole covers. Put an aluminum cap over the hand hole cover and would break bolts. Jack McClure welded up the ears solid on my housing, put thread inserts and now use a 1/2" stainless bolts with new hold down clamps. Thats the beef it needed to hold on. No problems since.
Make sure you have extra bottles of compressed air. I've had the pop off go at the start of the race for either not setting the pressure right, or having a low bottle pressure.
When do I stop learning lessons?
As for when you feel you need a pop off? when you realize you have a lot invested in your boat and yourself, and don't want to lose either one. Funny, you'll spend thousands on life insurance, but skimp on the safety equipment.

[superdave013]

Willis, if you need some braided hose made up let me know.
714 814 2503

[steelcomp]

Quote...LVJetboy: I'll back off on my safety comment but not the dumb design. Ok, sure it works to a degree. But if plastic lines need to be so precise (some apparently posting the result of not so precise) why not a more secure connection? I had cheap plastic lines leak on a PD, so I switched to hydraulic lines...no more leaks. A PD is not as critical as pressure relief in my opinion. So if a perfectly cut pastic hose ending is so critical to compression fitting seal on intake relief, what's the point
If the lines leaked on your PD it wasn't because they were cheap, it was because they were improperly or more likely sloppily installed.
Have you ever assembled braided stainless lines? Say you go with a -3 teflon-lined for high pressure? What do you think takes more time assembling, then, braided stainless lines or just being a little more careful cutting the ends of the plastic hose squarely? The plastic hose is a whole lot lighter, for those worried about weight, and if you think it's a "cheap" way to do it, look at the back of a 8000 hp 320+ mph Top Fuel Dragster. The clutch (and other) timing system is plumbed completely with high pressure plastic line. These guys have a lot bigger budget than any boat racer, and if you don't think it's safety related, I can tell you that anytime that anything dosen't go right with a top fuel dragster, it's a safety issue. I think if it's a good enough system to plumb compressed air for them, it should be adequate for this application. It's not rocket science.

[Cs19]

From what I hear, the little black hose is very reliable like Steel said.
Ill be using that on my data system.

[LVjetboy]

"Have you ever assembled braided stainless lines?"
Yes, quit a few thanks for asking. And they don't leak.
Did my black plastic leak because of the hose end? Or did they leak because of an over-tightened compression coupling? Or did they leak for some other reason? Not sure. Just that mine leaked as others have leaked. And hydraulic pressure may be higher than other applications like data monitoring.
But why not use a more reliable connection for a very critical application? More importantly, my poor design comment originally directed at bolt failure, not hose leak...although either is a bad thing.
jer

[steelcomp]

Quote: LVJetboy But why not use a more reliable connection for a very critical application?
Why use an unnecessarily overkill connection when the one designed for the application when used properly will work just fine? The idea is to do it correctly, and if a person can't pay enough attention to properly assemble a simple plastic hose end, I'd have to wonder what else on his or her boat will suffer due to the same lack of attention. It's not the part that's the problem, nor is it the application. But when you work on aircraft for a living, you get used to redundancy and overkill and understandably. There's just not a place to pull over and check your chit when your 30K' in the air!
You go, Jer Happy new year!! :D

[Unchained]

Well I guess the little black plastic hose and the bolts have been discussed to death.
The only thing left now is reengineering the bypass/popoff (s), it's (their) location, and the amount of water it (they) need to bypass. :rolleyes:

[UBFJ #454]

IHBA Rules require a PopOff's cylinder to be Minimum of 4 Inches in Diameter with Minimum 13 Sq. In. of UnRestricted Release Area ..... Key word Being "UnRestricted" ... Free OutFlow.

[LVjetboy]

"Why use an unnecessarily overkill connection when the one designed for the application when used properly will work just fine?"
Depends on the application. Plastic hose not "designed" for the application, but may work ok. If you're in the aircraft field no doubt you have experience with overkill. Why? Because "working ok" not acceptable as the standard goes up. Aircraft parts are designed to exceed "working ok" requirements and compensate for variations in quality control, installation and use. Right?
So why not also a part critical to race boats? Yes, I understand economics so on and so on. But for a race only part triggerd by pressure? Why would you not want to spend an extra $50 to make sure it worked no matter?
jer

[steelcomp]

"Why use an unnecessarily overkill connection when the one designed for the application when used properly will work just fine?"
Depends on the application. Plastic hose not "designed" for the application, but may work ok. If you're in the aircraft field no doubt you have experience with overkill. Why? Because "working ok" not acceptable as the standard goes up. Aircraft parts are designed to exceed "working ok" requirements and compensate for variations in quality control, installation and use. Right?
So why not also a part critical to race boats? Yes, I understand economics so on and so on. But for a race only part triggerd by pressure? Why would you not want to spend an extra $50 to make sure it worked no matter?
jer
OK Jer, you win. :sleeping: :sleeping: You're right. In fact, the next one I install I'm going to use cast iron pipe and swivel connections. :hammerhea

[steelcomp]

Well I guess the little black plastic hose and the bolts have been discussed to death.
The only thing left now is reengineering the bypass/popoff (s), it's (their) location, and the amount of water it (they) need to bypass. :rolleyes:
I can't help but agree with unchained...there's definately a simpler and probably more effective way of accomplishing the same thing, and certainly a more reliable way.
Will someone please, in one or two simple sentences describe the purpose of a pop off valve. I know HOW they work...I wnat to know what they are supposed to be accomplishing, or what purpose they are serving. This will make it a lot easier to identify a better solution.

[steelcomp]

IHBA Rules require a PopOff's cylinder to be Minimum of 4 Inches in Diameter with Minimum 13 Sq. In. of UnRestricted Release Area ..... Key word Being "UnRestricted" ... Free OutFlow.
OK...sorry...one more question. How did the powers that be come up with this requuirement? Is that simply the area of the hand hole opening? (piXdia=12.56 sq in.)
Thanks

[UBFJ #454]

A PopOff Valve Diverts the flow of water through the Impeller/Nozzle of the Jet Pump thus Diminishing the Force (Thrust) Propelling The Boat Forward.

[LVjetboy]

"In fact, the next one I install I'm going to use cast iron pipe and swivel connections."
That would be overkill you think? Plastic weak. Braided steel hoses just right. Cast iron belongs on a toilet? Along with gate valves?
jer

[steelcomp]

A PopOff Valve Diverts the flow of the water (Thrust) through the Nozzle of the Jet Pump thus Diminishing the Force Propelling The Boat Forward.
Thanks Jack, but I said I know HOW it works, I was asking WHY we need one? What is it supposed to be accomplishing? What service is it providing?

[steelcomp]

"In fact, the next one I install I'm going to use cast iron pipe and swivel connections."
That would be overkill you think? Plastic weak. Braided steel hoses just right. Cast iron belongs on a toilet? Along with gate valves?
jer
You're not serious, right, Jer? PLease tell me you're just joking. I know there's a sense of humor in there somewhere. :cool:

[LVjetboy]

"A PopOff Valve Diverts the flow of water through the Impeller/Nozzle of the Jet Pump thus Diminishing the Force (Thrust) Propelling The Boat Forward."
Or does the popoff diminish aft (transom or intake) lift caused by sudden shutdown? A bit different than diminishing thrust propelling the boat forward. Those two (thrust and lift) are prependicular and affect stability differently during shutdown. Not the same. Does the stablilty of shutdown depend on forward thrust or sudden bow down forces? As in bow steer? Forward thrust and transom lift affect a boats moment or bow down differently.
jer

[LVjetboy]

SteelComp I'm not joking.
jer

[UBFJ #454]

I, myself and me, ... All three (3) of Us ... Don't think Recreational Boaters need a PopOff (As Currently Being Built and Sold) ... Or, for that matter ... Should think they need one ... Recreational Boaters, in Our Three Opinions, Should Not Be Trying To Travel In A Straight Line As Quick/Fast As We Racers Attempt/Keep Trying To ... It's Irresponsible To The General Public And Their Children To Do So On Public Waterways.
The Reason we jet drag boats need such is that we need a semi "Clutch" to Disengage the Drive Train to Help Slow Us after going through the 'Traps' ... Much the same as parachutes for the prop boys ... When We Can Implement the Design of a Jet Pump Driven Boat To Run 200 +/- MPH, We're Going To Need The Parachutes Too ...
Note ... I can imagine a PopOff being Popped 'Off' in a Sharp Turn Having Distasterous RESULTS on a Lake/River Boat ... It,a PopOff, as currently Designed & Intended, Is Purely A Straight Line, 'Point & Shoot' Drag Racing Device ... Some variation of what now exists may be applicable and useful to/in recreational boating, but, it will have to be well thought out and will not be the same type of device you'all are focused on here.

[LVjetboy]

I, myself and me understand using a popoff (yet acknowledging it's design limitations) for your application. My previous posts addressed your application not mine. I did not mention a sharp turn or any other lake specific environment. After all, we're tallking about the original post: Pop-off/valve 101... here right?
jer

[Jake W2]

I think LV is on to something with the pop off letting the presure out keeping the transom down so the boat does not nose dive.That is wht I have been told.
Jake

[steelcomp]

I tell you what, between you (Jack) and Jer, I don't know who says more without saying ANYTHING!!! :sleeping: :sleeping:
Never effing mind...I'll figure this out myself. No one said anything about recreational boating, and besides, there's 'recreational' boats out there that will stomp the chjit outa' a WHOLE lot of quote-unquote RACE boats, and they recreate in an acceptably safe manner, so you can get off your thoro-bread high horses, bothayaz.
Jee frekin wiz!!!!! :confused: :confused:

[steelcomp]

I think LV is on to something with the pop off letting the presure out keeping the transom down so the boat does not nose dive.That is wht I have been told.
Jake
I've been told several different things, but all were supposition. I was hoping that someone with KNOWLEDGE could give a simple answer, but I dont think SIMPLE is available here. These things aren't space shuttles, although I think there are those who wish they were, or think they are. :sleeping:

[ONAROLL]

When water is traveling through an intake and through the impeller at 100mph and the motor suddenly seizes, stopping the impeller, a "blockage" occurs, with the loader still loading the pump and nowhere to exit a pressure bubble can occur under the boat forcing the transom up and the nose down resulting in a situation of bow steering (at 100 mph)..a pop off relieves the pressure to correct this situation....02....Vic

[Jake W2]

Roger ran the R and D Express said when he crashed or got pitched out of his Cheyenne at over (120) I think it was because when his scoop let go of the throttle the sudden slow down (and his pop off not working)it was stuck, raised the transom and the boat dug a sponson in and over he went.He said his never worked rite and they had to put new orings in all every time it poped off.To the best of my memory that is what he told me. :confused:
Jake

[steelcomp]

Thanks guys. So it's my understanding that it's related to shut down issues and overcharge of the intake. I thought that the jetaway was for the engine shut down problems, allowing the impeller to keep turning. I had the pop off explained to me once that it was so guys could run their shoes deeper, and not have such radical shut down issues. Is this accurate? I knonw my Bahner recreational boat that runs a meezly 95 or so has some pretty serious shut down issues already. I bet that most 100+ mph recreational jets with a performance set up under them have shut down issues, so maybe there is a need for something a little more simple and unobtrusive for safety's sake, even for us recreational boaters. By the time I'm done with it, my "recreational' boat's gonna run a whopping lot faster than 100, so I'm interested in this STRICTLY for a safety feature. I wouldn't want to get pitched and have my run away boat take out some innocent kids or something, eh, Bear?

[WheelerDealer]

As the thread starter I have another question if y'all don't mind...If you are running a Jet-A-Way as most racers do I believe, and a pop-off valve as well and the pop-offs as earlier stated in this thread are triggered by pressure, how then if you have an unexpected engine shut down at speed would there be enough of a pressure increase to trigger the pop-off if you have a working Jet-A-Way??? Would'nt the Jet-A-Way allow the impeller to keep spinning and passing water so that there would not be enough of a pressure build up to trigger the pop-off? I could definitely see the pop-off being usefull as a shut down tool while you were still under power and wanted to manually trigger it to slow down considerably without backing out of the gas a whole lot and allowing the boat to settle easier.. It just seems to me that if the Jet-A-Way actually works that it would keep the pop-off from triggering..Does anybody get what I'm saying?? Is my thinking off here??
Oh ya, I also don't understand the plastic hose issue either, I mean they probably work fine, but why not spend the extra money on steel braid just to be sure on a potentially life saving device? If you got the $2000.00 to spend on a pop-off you can handle another $50.00 for braided lines. I do also agree that regardless of which hose is used that great care should be taken when assembling the ends.

[Unchained]

IHBA Rules require a PopOff's cylinder to be Minimum of 4 Inches in Diameter with Minimum 13 Sq. In. of UnRestricted Release Area ..... Key word Being "UnRestricted" ... Free OutFlow.
Thanks Jak, that's what I was looking for.
With the rule book stating the 4" diameter then the hand hole cover is the only place that a popoff could go to be IHBA legal.
So the archaic IHBA rules prevent any new engineering again.
I'm not surprised, the IHBA rules don't allow EFI systems or intercoolers either even though many passenger cars have them.
When I was at the finals I talked to the owner of the only TAH turbo boat and he was frustrated that IHBA wouldn't let them run EFI and they had to run a totally homemade mechanical fuel injection system that is a constant tuning challenge.
Well for my uses the IHBA rulebook isn't a limitation or a factor.
The unrestricted part is interesting though. With the popoffs I've seen it looks like the valve lifts and the water flow hits the end of the 4" plug.
Not really a smooth path for water flow.

[superdave013]

Mark, you can use intercoolers with IHBA.
Good reading here, carry on. :)

[steelcomp]

I'm assuming that the idea here is an instantaneous dumping of the pressure, which I also think isn't necessary, especially with the addition of the jetaway. There ought to be a way to keep the system from overpressuring at a constant rate. There are thousands of applications for system pressure relief and pressure regulation so it dosen't seem to me that re inventing the wheel is the problem here. It seems that someone, somewhere just used the hand hole out of convenience, and it sorta workes, so that became the rule. I'm not saying the hand hole cover is not a goos place, but lets face it, at 85 psi with 13 sq. in. that's over 1100 pounds being applied to the unit. Something smaller that worked on a more continuous basis would see a lot less stress. Or maybe a couple of smaller units to help keep up the volume. I also recognise a need for a driver override, but if the unit was working in a more continuous manner, that need would be less critical.

[Duane HTP]

It just seems to me that if the Jet-A-Way actually works that it would keep the pop-off from triggering..
This is true in a lot of cases. The JETAWAY releases the pressure instantly when it's MOST important. However, the Pop-Off works well with it all the way down in speed. We've even made systems where the JETAWAY triggered the Pop-Off so that it came into play earlier in the shut down. Worked well, David Kirkland had one on the old Smokin and Strokin Boat.

[LVjetboy]

"I was hoping that someone with KNOWLEDGE could give a simple answer"
Good luck with that SteelComp. And the simple answer's not always right. No matter who gives it.
"...his pop off not working it was stuck, raised the transom and the boat dug a sponson in and over he went. He said his never worked rite and they had to put new orings in all every time it poped off."
If true, that's a dumb design...as I posted earlier.
"Wouldn't the Jet-A-Way allow the impeller to keep spinning and passing water so that there would not be enough of a pressure build up to trigger the pop-off?"
That would depend on the pressure trigger point, the boats speed and intake setup. A jetaway relieves pressure during sudden shutdown BUT NOT ALL intake pressure. That's why under some conditions, a popoff can help too. What are those conditions? Well, that depends on how fast you go, your intake setup and how sensitive your hull stability is to a sudden change in pitch. Do you know that? Does anyone know that?
Steelcomp, is that simple enough for you?
jer

[bp]

"A PopOff Valve Diverts the flow of water through the Impeller/Nozzle of the Jet Pump thus Diminishing the Force (Thrust) Propelling The Boat Forward."
Or does the popoff diminish aft (transom or intake) lift caused by sudden shutdown? A bit different than diminishing thrust propelling the boat forward. Those two (thrust and lift) are prependicular and affect stability differently during shutdown. Not the same. Does the stablilty of shutdown depend on forward thrust or sudden bow down forces? As in bow steer? Forward thrust and transom lift affect a boats moment or bow down differently.
jer
sorry, i've been gone for 4 days on a business trip. couldn't keep up. business trips are great. now i'm sick.
jer is correct. the purpose of the popoff valve is to vent the suction piece, basically allowing suction pressure to drop to 0 and negating lift at the transom in loss of power conditions, or in the event the driver just feels the boat is getting out of control (manual initiation).
this does not mean the pump would be starved. that's a seperate discussion.
the jetaway doesn't work like this. if you look closely at data, backing way off the throttle at the end of a high speed run, rpm drops, suction pressure spikes up a bit, but discharge pressure rolls over and slowly comes down as the impeller ratchets down. depending on a myriad of other things, a person could still get spit. stuff does happen. the point is, the jetaway does not dissipate suction pressure the same way the popoff does, but it does work instantaneously to dampen the suction pressure spike that will occur upon loss of power or a significant reduction of power at high speed.
the popoff does not work instantaneously, but must have a high suction pressure signal or a driver signal to activate. the high suction pressure signal is usually set to the requirement of the boat owner/driver. willis' setpoint may be different than brule's, may be different than don harris's, may be different than traylor's, may be different than nagore's, etc.
the best demonstration of both devices working together i've ever seen was at bakersfield 5 years ago. we'd broken a valve in the biz, so kz and dave had left and i just stuck around to watch. i was sitting at the finish line, and don harris was making a pass. right at the finish line, he threw a blower belt and lost power. he never even moved in his chair, the daytona just settled in, went perfectly straight, and slid to a nice easy stop. not bad from 139mph...
whether someone decides to use plastic tubing or braided steel is a personal choice, and wasn't my point. of course the stuff needs to be put together correctly. in the case of a miersch or hart (if you can find one) valve, the control system is pneumatic and from what i have been told, it must be precisely calibrated. i do know that in a pneumatic control system, if you change things, you can alter the calibration, which can affect performance.
the miersch/hart and nelson valves are the only one's that really matter. the old wilder (spring) valve doesn't really count because it didn't open far enough to release enough water, and it was manually operated (rope pull). the miersch/hart valves are pneumatic, the nelson is electric. i used to operate boilers with pneumatic control systems, and you really had to stay on top of them. the other is basically a solonoid in a very harsh operating environment. in both cases, the design is sound from an industrial perspective, and as has been demonstrated, the failures have really been associated with the companion components (pump ears), assembly (tubing connections), or missed pm.
in any case, the market for these valves is very small. not a huge demand for someone to invest in a great deal of design engineering, considering the design and operating parameters.

[bruleracer]

bp, spoken like a true engineer, with one exception, you have been there and done that, besides having valid data.
couldn't have said it better myself...
when i was an engineer my favorite part was getting to blow the wissle and wear that cool striped hat!!!
(just kidden on the last part, i really didnt like the hat)
brule

[bp]

yer always whistlin... :cool: see ya in a couple weeks.

[steelcomp]

Thanks, bp. As usual, you speak the english I understand. That was exactly the answer I was looking for.
Glad you're back...sorry you're not feeling well.
steel

[LVjetboy]

SteelComp, glad you got your answer! :rolleyes: I was just filling in until pros who spoke English (you understand?) stepped in. Schmooz all you want. BTW, Bp's post did not contradict mine, only added experience.
"in any case, the market for these valves is very small. not a huge demand for someone to invest in a great deal of design engineering, considering the design and operating parameters."
True small market. That doesn't mean the design's inherently good or even at the level it should be for that limited market. In fact, a limited market means a poor design from one or two suppliers is all you got to use regardless of that designs worth. "Dumb" may be a bit overstated on my part, but reports on trigger point and mounting bolt failures? Seems a bit lame. Why not something better? As Steelcomp said, not rocket science.
jer

[steelcomp]

SteelComp, glad you got your answer! :rolleyes: I was just filling in until pros who spoke English (you understand?) stepped in. Schmooz all you want. BTW, Bp's post did not contradict mine, only added experience.
"in any case, the market for these valves is very small. not a huge demand for someone to invest in a great deal of design engineering, considering the design and operating parameters."
True small market. That doesn't mean the design's inherently good or even at the level it should be for that limited market. In fact, a limited market means a poor design from one or two suppliers is all you got to use regardless of that designs worth. "Dumb" may be a bit overstated on my part, but reports on trigger point and mounting bolt failures? Seems a bit lame. Why not something better? As Steelcomp said, not rocket science.
jerONLY added experience...that's a good one, Jer.
Knowledge with no experience is supposition. Knowledge with and from experience is wisdom and truth. You say a lot of smart stuff, but weather you think it's "schmoozing", or not, I have a LOT of respect for bp's "experience".
You're awfully critical of a lot of things, but funny thing is, you never seem to come up with a better idea. You're a seemingly capable guy, why don't you jump in here and build all of us the ultimate device to solve this overcharge problem. C'mon Jer, show us what you got. :idea:
"C mon.
Don't be shy.
You can do it.
We love ya, Jer...we need ya. :sleeping:

[bp]

hey scott, thanks. feeling much better this morning, wonders of good drugs :p. project is done, everything is nice and tidy, and everything works (yippee!). 'course, after looking at it there's one more thing i want to replace and that will be complete today. tool worked great.
jer i completely understand and feel the same way about having a low threshold for failure. do i think that a better design could be developed? certainly. but i want to throw one more caveat out there. the valves that are currently in use work just fine in the vast majority of boats they are installed in, in repetitive use, without failure. that tells me this is not solely a -valve- design issue.
this seems to go back to the mounting bolts because jak talked about the fact he changes his all the time, willis launched his, jerry lost his, and jerry francis broke his. the valve is mounted to the handhole which is the highest vent point on the suction piece. when these operate to the full open position, there is a tremendous amount of force behind them. the miersch/hart valves can be strapped to the suction piece.
the nelson valve has an approximate 4" diameter plug that rises about 3+" to open. this plug is the valve, and contains a coil. it weighs at least a pound and a half, and rises with tremendous force when released by being denergized. there are internal dampeners to soften the hit, but there's still significant force. there's no real way to strap the thing down to the suction piece. there are a lot of internal pieces to this valve, and you have to pay strict attention to it. all that force is transmitted to the bolts that are holding it to the suction piece.
i always believe things could be improved. not only from a design perspective, but with the incorporation of newer technology. it's a matter of someone that understands the parameters, wanting to take the time and effort to do it.

[Unchained]

Thanks for the input Bob.
I'd like to get your input also about suction pressure.
I've asked a question on Banderlog and RJB about suction pressure and never got what I considered to be a valid explanation even though I have my own ideas.
Duane stated before that it takes about 35 # of intake pressure just to keep the pump loaded properly. OK, I can see where force feeding the pump probably is beneficial to a point even though it all has to come out a small 3" hole in the back.
It seems to me that any suction pressure above that 35# is just spilling out the front of the intake and that is ONLY used as a method of giving the hull additional lift. The hull is riding on a pressure wave that can't go through the pump.
The depth of the shoe is certainly causing additional drag but it is more than offset by the additional transom lift.
I experienced this with my Cheyenne. The shoe too deep would cause the back end of the boat to hop around even while accellerating at WOT.
[QUOTE=bp]the purpose of the popoff valve is to vent the suction piece, basically allowing suction pressure to drop to 0 and negating lift at the transom in loss of power conditions, or in the event the driver just feels the boat is getting out of control (manual initiation).
And to further complicate things all that suction pressure is causing what you described in the above sentence.
Previous forms of this same discussion are what prompted me to discuss this in detail with my friend " Old Guy " and he came up with a CAD sketch of the duct that I fabricated and used all last year.
The purpose of the duct was to use less suction pressure and get transom lift from the additional planing surface on the bottom of the duct.
Also to contain the pump overcharge on shutdown.
Am I on the right track ?
Hit me !!

[bp]

mark, i have no idea what duane might mean by saying "minimum of 35". i wouldn't agree or argue with that, because i don't know if he's saying at the impeller suction face, at the mouth of the intake, wall of the suction piece, what?? steady state i assume? dunno..
i'll tell one story i've told before. in '01, we had been having some problems early in the year, and really wanted to do well at red bluff. at red bluff, we had a problem with the popoff (nelson) opening early on its own. we took the thing apart as we always did, looked everything over, replaced some things but didn't see anything wrong and put it back together. put it back in the water for the last qualifying round. kz was running against clint's comp hydro. of course, the popoff went off at half track, and i'm thinkin' crap here we go again. i see an 8.20something and think we're gonna suck. when they get back to the pit, keith hands me the slip and he actually ran a 7.94 with the popoff open from half track to the finish line. clint ran the 8.20 something.
we had racepak data on the biz. in looking at the data, both suction pressure data points (on the suction piece walls) dropped to 0. but, bowl pressure only dropped slightly from about 360 to about 350-355. so, with the popoff open for half the run, it ran an et that was .13 slower than what is still the world record it holds for the class.
i cannot visualize water spilling out of the front of the intake. i can visualize water flowing around it, but not spilling out of it.
to go back to 35 for a moment, if 35 provides sufficient volume, that's good. if 35 does not provide sufficient volume, then you need more than 35. if 35 provides too much volume, then it needs to be reduced.
getting lift from things other than suction pressure is a good idea. but, other than a popoff or jetaway, i'm not really sure what you do about overcharging the pump suction on shutdown, or what you mean by "containing" pump overcharging? idwannahitya... i do think ya oughtta bring it to phoenix next time though.. :2purples:

[Unchained]

Hmm......
I still have no explanation......Thanks anyway.
I can't see myself topping that boat out until I get a handle on understanding suction pressures, safe shutdowns, and reliable popoffs.
I see seasoned jetboat racers still have accidents and don't need that.
" Old Guy " is making a CAD drawing of our perception of things and we will post it for some further discussion.
Mark

[bp]

sorry mark, i guess i'm either not quite grasping the question, or i just don't understand it enough to provide the answer your looking for.
as far as seasoned jetboat racers having accidents, there are other things that can happen that a popoff or jetaway won't help, and the accidents i've seen, they were not a factor.
if you're asking me a question about shoe depth, i'm not quite sure i understand what it is???

[bottom feeder]

Well rocket men were is my first submission for the pop off. While this is only a concept what do you think. My constraints for ideas where. Fail safe, simple to use and matain, as few working parts, mostly comprized of off the shelf parts.
http://www.***boat.com/image_center/data/520/1501pop_off.jpg
Blue line = suction housing pressure tap
silver canister = air over water canister
red line = co2 source (regulated to "X")
Purple = double acting air cylinder
peach = fabricated hand hole cover/ adapter
yellow = 2" sst ball valve (1000 psi working pressure)
Over view is the air cylinder is charged with co2 (red line) to hold the air cylinder in the compressed state.
Once the intake starts loading and building pressure (blue line) it will force the water up into the air over water chamber creating the air pressure to overcome the intial co2 charge.
This will extend the air cylinder causing the ball valves to open and relive suction housing pressure.
Thoughts are the curant valve has to much mass in the piston resulting in a impact failure of the housing / mounting and fasteners.
Now it is time for some to start shooting and others to offer up improvement. How many are willing to post up?
If anyone has a design and someone with a ability to test let me know I would be more than willing to assist in anny way.
Best regards :)

[bp]

are those ball valves or butterflys, and if they're balls, how large are the passages? 2"? how much pressure does it take to open those with 100psi against the seat, and how much pressure would it take to open a 4" with the same pressure against the seat?

[bottom feeder]

Bp.
The valve is supposed to be 2" thru we will see i ordered up some just to check out. their tec says the opening pressure stays the same loaded or un loaded We will see i guess?

[UBFJ #454]

bottom feeder -
Just a comment about one of the basic elements of the CAD Sketch you posted ... Nothing Derogatory ... Just a Comment .....
If I were going to install something like your proposing on any boat of mine, I would want the relieved h2o to exit the system at an angle no more than 45 degrees from vertical ... The abrupt Straight Down Force of the by-passed water (Planting The Keel & Intake Severly Into The Water) may cause a rather undesireable situation in terms of high speed handling which would be different for different types of hulls (In General) and boat/speed specific in all cases. It is my opinion that some Significant Component of Forward Force should be exerted by the by-passed h2o even while it is causing the boat to Slow its forward motion by not going through the pump .....
Just a Thought.

[bottom feeder]

Bear thanks for info. The model was just to help visualize. I spent about a half hour drawing it. I will be the first to admit i know less nothing of a pop off valve other than what i read. My thought was an exit could be fashioned to afix to the other end of the valve to direct flow as needed. no offence taken here i really enjoy the exchange of knowlege.
Best regards

[steelcomp]

Those 2" ball valves are going to require a helluva force to open under pressure. Even static, they would require quite some force together. You'd either have to have one stout actuator, or a long lever arm, which would require a long travel actuator, which might make the unit kind of tall and obtrusive. Why two valves? Just purely for volume?
It looks effective enough, but it still seems thast most of the problems arise from the structural design, not really the efficiency of the current valves, and from what I can tell, the structural flaws are more in the suction piece and the hardware, not the valve. Of course, with that 4" piston hitting the top of that housing, you get a slide hammer effect which if eliminated, might help reduce the attatching hardware failures...sorry...just thinking outloud.
Zero pressure in the suction piece dosen't seem to me to be a problem. It just tells me that the flow through the pump is equalized before and after the impeller...sort of an ideal condition. I would think it would be somehow beneficial to have a pressure reulator on the suction piece that worked continuously so as to maintain some sort of "ideal" pressure, eliminating changing conditions under the boat. I don't know if this could also be used as the safety device for sudden overcharges as on shut down, or if you'd run a seperate device (such as the pop off) for the high volume dump. :idea:

[bottom feeder]

Steel i would agree on most points I would say the slide hammer effect is the cause for all the hardware issues. It is applying massive shock loads to all the critical retention points. The problem is the only way reduce the shock load is to reduce the mass or the rate of travel. The effort with the spring and rubber pads solves nothing. The energy is still applied although much of the shock is reduced the force is still the same. I am just trying to get the old idea machine going and discuss this topic in a differant light

[steelcomp]

Steel i would agree on most points I would say the slide hammer effect is the cause for all the hardware issues. It is applying massive shock loads to all the critical retention points. The problem is the only way reduce the shock load is to reduce the mass or the rate of travel. The effort with the spring and rubber pads solves nothing. The energy is still applied although much of the shock is reduced the force is still the same. I am just trying to get the old idea machine going and discuss this topic in a differant light
Feeder, I see that as the biggest advantage of your design...eliminating the slide hammer. The ball valves I'm familiar with are those used in common plumbing, ie: the brass ones which are teflon lined (arouind the ball) with a highly polished stainless steel ball, and the PVC type used in irrigation or air supply. I'm sure there's others in industrial applications, though. I think you're on to something.

[bp]

i don't think you'll have a problem finding a slave to operate the valve, but you may have to use a higher pressure.
but, i think you might be able to find something a little more exotic for a control system. perhaps the pressure converted to an electronic signal, an electronic regulator to automatically/manually open the air/co2 supply to the valve operator. there are some very nice/reliable electronic regulators that would make the control system a whole lot better.
i am also not all that keen about the fulcrum. too many moving parts. fewer moving parts, the better. also, you can diver the exhaust with half a Ubend.

[steelcomp]

I agree about the linkage...but I think that could be made reliable enough. I think the benefit of eliminating the sliding piston is worth it. Good call on the solenoids on the air bottle. I agree that you could get a slave with enough oomph. More I think about it, I think a butterfly would work better with a dual action slave cyl. You could open AND close on demand.

[LVjetboy]

"Knowledge with no experience is supposition."
Oh come on. True knowledge comes from both experience and the ability to project outcome or draw valid conclusions based on those experiences.
Experience first-hand or recorded by others makes no difference. Knowledge implies facts, data, comprehension and understanding...those hard to have if it's all just supposition from someone who has no grasp of the facts or ability to comprehend and draw valid conclusions you think? But just experiencing one thing or another doesn't mean you can draw a valid conclusion or have knowledge.
And just because you or I haven't first-hand experienced one thing or another does not mean we can't draw a valid conclusion or have knowledge based on others experiences. Happens all the time in science and other fields and is the basis for new discoveries. You think? Duh. But let's not get all philosophical here.
"You're awfully critical of a lot of things, but funny thing is, you never seem to come up with a better idea."
Maybe you haven't seen any of my new ideas? On the forums or for that matter in person?
jer

[LVjetboy]

Back to the thread.
"jer i completely understand and feel the same way about having a low threshold for failure. do i think that a better design could be developed? certainly...seems to go back to the mounting bolts because jak talked about the fact he changes his all the time, willis launched his, jerry lost his, and jerry francis broke his."
To me, a better design is not only needed, but doable and can be cost effective. The fact that the current design is dated and continues to fail is why I posted, it's a "dumb" design. Or if you don't like that term, than at least an immature or dated design? Compared to what I think can be achieved within the limited market that is.
For one thing, I think the popoff should be designed to automatically reset once suction pressure drops below an operator adjustable level. Otherwise maket limited to race only application.
On the 35 psi? As bp said, depends on where you measure pressure as well as your tap configuration...there's ballpark but no magic intake pressure number. But there is a specification called NPSH which is defined as the minimum suction conditions (pressure) required to prevent impeller cavitation. More than this number could cause excessive intake drag, less a hit in pump performance. Not so much volume as pressure driven.
So my "inexperienced" guess is; ideal intake pressure is related to a number like NPSH which keeps the impeller loaded but not to the point of overcharging the intake and causing excess intake drag.
jer

[Unchained]

Bottom Feeder,
Nice cad drawing.
I really enjoy seeing new ideas.
I think ball valves could work if they were dissassembled and additional clearance machined into the nylon so that they operated freely.
Here's my thoughts,
One of these on each side, 2.5" with a spring loaded butterfly valve on the end of each one. A regulator, not a popoff.
Relieving the pressure at the bottom of the suction piece rather than at the top.
http://www.childsdale-ind-prop.com/proto1.JPG
http://www.childsdale-ind-prop.com/proto3.JPG
I'm concerned with how long that masking tape will last in the race environment though...........

[bp]

To me, a better design is not only needed, but doable and can be cost effective. The fact that the current design is dated and continues to fail is why I posted, it's a "dumb" design. Or if you don't like that term, than at least an immature or dated design? Compared to what I think can be achieved within the limited market that is.
For one thing, I think the popoff should be designed to automatically reset once suction pressure drops below an operator adjustable level. Otherwise maket limited to race only application.
On the 35 psi? As bp said, depends on where you measure pressure as well as your tap configuration...there's ballpark but no magic intake pressure number. But there is a specification called NPSH which is defined as the minimum suction conditions (pressure) required to prevent impeller cavitation. More than this number could cause excessive intake drag, less a hit in pump performance. Not so much volume as pressure driven.
So my "inexperienced" guess is; ideal intake pressure is related to a number like NPSH which keeps the impeller loaded but not to the point of overcharging the intake and causing excess intake drag.
jer
"dated", i'll go with. auto reset would be a bad thing, and in fact would be against the rules which specify that the valve must not have an auto resetting capability. reason being is that the valve's ultimate purpose is to provide safe shutdown upon loss of power from high speed (read real high). if the signal is suction pressure, and it drops to 0, and then you have an auto reset feature that resets it while the boat is still over, say 120, you could have a very serious problem. even having the capability means somebody would mess with it, do something at the wrong time, and you'd have a problem. just not a good thing.
you do need net plus a couple, just to be on the safe side :cool:
mark, every suction piece i've ever seen fail has failed along the side. i don't know that much about it, but i don't think boring a hole through the side would be a good thing to do, strength wise.

[bp]

bottom feeder, couple things to keep in mind. it is true the current valves "pop" open, then stop against a stop. when they do, a lot of force is transmitted to the bolts holding them to the suction piece. there are internal components attempting to dampen this force, but of course you can only dampen so much.
the other part to this is that the valves DO "pop" open at the instant the driver touches the button. this is important from a safety aspect, when a driver needs it (just ask willis), he really wants it NOW :jawdrop: point being, it's going to be real interesting to find out how long it takes for the ball valves to open under pressure. if they cannot operate, like, right now, they may not be best suited for this, which is not to say the concept isn't right, just that the valve type may not be right.

[steelcomp]

So you say, Jer. :sleeping: :sleeping: :sleeping: "Knowledge with no experience is supposition."
Oh come on. True knowledge comes from both experience and the ability to project outcome or draw valid conclusions based on those experiences.
Experience first-hand or recorded by others makes no difference. Knowledge implies facts, data, comprehension and understanding...those hard to have if it's all just supposition from someone who has no grasp of the facts or ability to comprehend and draw valid conclusions you think? But just experiencing one thing or another doesn't mean you can draw a valid conclusion or have knowledge.
And just because you or I haven't first-hand experienced one thing or another does not mean we can't draw a valid conclusion or have knowledge based on others experiences. Happens all the time in science and other fields and is the basis for new discoveries. You think? Duh. But let's not get all philosophical here.
"You're awfully critical of a lot of things, but funny thing is, you never seem to come up with a better idea."
Maybe you haven't seen any of my new ideas? On the forums or for that matter in person?
jer

[steelcomp]

Bottom Feeder,
Nice cad drawing.
I really enjoy seeing new ideas.
I think ball valves could work if they were dissassembled and additional clearance machined into the nylon so that they operated freely.
Here's my thoughts,
One of these on each side, 2.5" with a spring loaded butterfly valve on the end of each one. A regulator, not a popoff.
Relieving the pressure at the bottom of the suction piece rather than at the top.
http://www.childsdale-ind-prop.com/proto1.JPG
http://www.childsdale-ind-prop.com/proto3.JPG
I'm concerned with how long that masking tape will last in the race environment though........... :idea: :idea: :idea: Isn't that a lower pressure area in the intake that at the top?

[cyclone]

this is cool. With any luck you geniuses will design and build something that doesnt cost almost two thousand bucks. I'll be patiently waiting but please, try to get it done and shipped to me at least one week prior to race season. Is that asking too much?

[Unchained]

:idea: :idea: :idea: Isn't that a lower pressure area in the intake that at the top?
I'm planning on venting as close to the water surface as possible. Just up from the shoe.
I intended on welding on a boss into the side of the suction housing. About 1" thick x 3/4" wall aluminum that a stainless 2.5" tube would slide into. If you can bypass any pressure over 35# as well as any spikes then the housing should hold up a lot better.
I have seen the pictures of the broken ones also. In the pictures I seen from Jak's boat it seems like the broken part was farther forward, near the bearing housing.
The Dominator is a stronger design because it has the ribs in the side.

[bp]

mark, i've seen more than one crack from the intake to the bowl flange, but you are right, none of them were amts and they do appear to be stronger. however, i don't think i'd want to weaken it by boring a hole in the side when there's already a hole in the top.
why do you feel strongly about placing the vent path at that point, rather than at the top?

[Unchained]

I feel the water will be leading up into the pump from the biting edge of the shoe which is about 6" in front of my vent point. I would have really liked to vent from right above the ride plate but it's too tight there.
Loaders were created to bring the water to the top of the pump because it wants to follow a straight line from the water surface.
I'm just trying to follow what I feel is common sense here.
I appreciate your's and anyone else's feedback.
You can see in the picture the duct that I've used for 40+ hours of boating last year.
I'm going to remove it and modify it so that I can change the angle of the bottom easily.
I feel there's a lot more to explore there.

[steelcomp]

This sounds like a good place for dumpimg the pressure, and I think welding the flange you're describing will more than make up for the hole AFA weakness is concerned, but for this to be a viable option for the other type, mfgr's would have to start casting intakes with this (these) flanges in them, otherwise this would be a really expensive mod for regular guys. And we haven't even gotten to the valve part.
Not trying to throw water on your project or idea...I like it and r&d has to start somewhere. Cool that you're willing to do this. Who knows...a few years or so from now maybe every intake will come with this already done, and the system will be readily available.
Are you going to try and create a system thast will continually regulate the presure of the intake? Will it have a driver override capability for an insta-dump? (Although with enough volume, I don't see that this would ever be necessary if the intake was never allowed to exceed a certain pressure.)
Now you got me looking at mine.

[Cs19]

Unchained, dont forget about the distortion due to welding. Thats pretty close to the wear ring socket,bowl flange and register. Id hate to see you damage your nice parts there.
Lots of suction housings that are damaged are not repairable for just that reason, after you weld them, they are so warped and distorted they are not useable.
About regulating or bypassing excess inlet press..... How about that spring loaded pop off? If you get the correct spring rate in it, it should bleed off anything over that spring rate thats in it.Now if we could only get it to flow more water out the exit.
Carry on. Enjoying the thread..Cs19

[Cs19]

http://www.childsdale-ind-prop.com/proto3.JPG
if we go this route,I say we do 4 individual 1/2 pipes on each side, so it looks cool. It would be like zoomies coming off the intake.
Cs19 trying to be funny. HAHA

[steelcomp]

Unchained, dont forget about the distortion due to welding. Thats pretty close to the wear ring socket,bowl flange and register. Id hate to see you damage your nice parts there.
Lots of suction housings that are damaged are not repairable for just that reason, after you weld them, they are so warped and distorted they are not useable.
About regulating or bypassing excess inlet press..... How about that spring loaded pop off? If you get the correct spring rate in it, it should bleed off anything over that spring rate thats in it.Now if we could only get it to flow more water out the exit.
Carry on. Enjoying the thread..Cs19
Now days there are actually bonding materials thast would be near as atrong as the weld, without the distortion. I think a competant welder could weld that with minimal distortion using heat sinking compounds. Reverse polarity, maybe? Good thought, Chris. And I like the four pipes. :hammer2:

[steelcomp]

Unchained, dont forget about the distortion due to welding. Thats pretty close to the wear ring socket,bowl flange and register. Id hate to see you damage your nice parts there.
Lots of suction housings that are damaged are not repairable for just that reason, after you weld them, they are so warped and distorted they are not useable.
About regulating or bypassing excess inlet press..... How about that spring loaded pop off? If you get the correct spring rate in it, it should bleed off anything over that spring rate thats in it.Now if we could only get it to flow more water out the exit.
Carry on. Enjoying the thread..Cs19
Problem with the spring regulated pop off is that the further the valve has to open, the higher the spring rate gets, meaning the pressure would have to increase as the valve opened further. Once the valve begins to open, theoretically the pressure begins to drop, closing the valve. Only way to get it to "dump" is to open it manually. I noticed the spring types use heavy valve springs. If we're only talking about 35psi or so, those might be replaces with a much lighter spring, which would have a softer spring rate, allowing more opening of the valve. There's about 450 lbs of pressure @ 35psi on the valve (13 sq. in.) so you'd need about 225 lbs of seat pressure on those springs. Guess that's why they use valve springs. In that caase they'd need to be a lot longer to stay near that rate. Unfortunately no matter what spring you use, it's going to increase in pressure as you compress it.

[Unchained]

I'm not that concerned about the welding distortion.
If you preheat the whole casting rather than just the area you're going to weld at the distortion is minimised.
As far as the spring and the valve, Old Guy has some great ideas on that. It's not going to take much spring for this and how it's mounted will control how it responds.
As far as a manual release, I guess someone could add it, but if it's designed correctly then there should be no need.
With two of them the odds of a malfunction are reduced dramatically.
If I have to sacrifice a suction housing to try something then it's not the end of the world. Worst case scenario is I have to make a plug for the hole.
If I had a broken suction housing I would have welded it and reinforced the broken area.
That's one of the great things about working with aluminum, grind out the crack and weld it up.
I've seen some huge repairs in aluminum engine blocks.
It has to be a clean casting to start with though. If it has a lot of junk casted in with the aluminum then it can be a pain to weld.
Here's what I welded up today,
http://www.childsdale-ind-prop.com/intercoolerbox.jpg
Converted the intercooler box to a top loader.
Shown upsidedown in the picture.
CS19, If you only knew what I intend to do with the end of the tube AFTER the valve.................

[steelcomp]

Man, you're just having too much fun. I'm in the garage today...cleaning, cleaning, cleaning. :notam:
Nice fab work.

[LVjetboy]

"auto reset would be a bad thing, and in fact would be against the rules which specify that the valve must not have an auto resetting capability. reason being is that the valve's ultimate purpose is to provide safe shutdown upon loss of power from high speed"
Rules are rules. Not that a valve can't be designed for safe shutdown even with auto-reset capability. Rules are rules.
Consider this, a valve with quick reaction to high intake pressure (as in less than 0.5 seconds to full open) but slow (5 second) auto-return once intake trigger signal's below the lower pressure threshold. Dampened, either mechanical or digital. Not hard to design. But certainly not spring activated.
If intake signal pressure drops to zero, slow reset will dampen a sudden intake relief valve closing spike in intake pressure. If during slow reset, intake pressure climbs above trigger point, the valve quickly triggers full open again and relieves pressure. Although I doubt that would happen if the return is properly dampened by a delay...for example, you'd be well below 120 and stable before full reset if the delay was 5 seconds.
Steelcomp, :sleeping: just sleep on thru this post. Nothing to see here. :sleeping: Go home and carry on your business.
jer

[steelcomp]

F uck off, Jer.

[bottom feeder]

Nice to see some valid input.
As was mentioned i think the best cotrol device would be pressure sensors rigged to some sort of control box that controled selonids for the co2. The ball valves my not be the way to go i do not know. I do know they are worth a look at as are many other options.

[bottom feeder]

http://www.childsdale-ind-prop.com/intercoolerbox.jpg
Converted the intercooler box to a top loader.
Shown upsidedown in the picture.
CS19, If you only knew what I intend to do with the end of the tube AFTER the valve.................
Unchained,
With aluminum welding and fabricating skills like that why in the world do you have a glass boat??
Just a cheap shot from a tin can jetter :D

[Unchained]

Unchained,
With aluminum welding and fabricating skills like that why in the world do you have a glass boat??
Just a cheap shot from a tin can jetter :D
I would rather have an aluminum hull. I looked at a 21' Eagle tunnel and am still considering one.
I wish they made a picklefork though.

[LVjetboy]

"F uck off, Jer."
No need to get hostile...keep it technical. And feel free to sleep through my posts. :D
jer

[steelcomp]

Huh...? Was I being hostile??
Sorry Jer...didn't mean to ruffle your feathers. Wake me up when you post something worth reading. On second thought,
Don't bother. Actually, you post a lot of interesting stuff, you just have the personality of a dial tone.
OOps. Sorry...I'll be nice.
(Damn, I hat it when it does that...) :cool:
So Jer,
What's your idea here on the perfect pop off valve, or device to control the unwanted overcharge? You've given us your analysis of everyone elses ideas, but how 'bout your own? In laymens terms so the stupid ones like me can understand. And type slow...I don't read so fast.

[Old Guy]

Mark "Unchained" and I have been kicking around a few "different" concepts with the idea of making jet boat racing a little safer. I have always been interested in controlling the intake pressure so that no matter what, it never will be the cause of a boat doing anything bad. I have come up with what I think is an original idea to control intake pressure. It involves adding a section in front of the bowl. This section contains all of the apparatus for the desired control.
http://files.triton.net/old1/1relief_side.jpg
This is not in any way like a "pop off" valve. There are "butterfly" type valves on each side of the bowl. It does not require a lot of force to operate this type of valve.
http://files.triton.net/old1/1relief_top.jpg
I think that I have put enough thought into this concept to have answers for most (if not all) of the questions that might arise.
THESE ARE CONCEPT DRAWINGS.
OK, SOCK IT TO ME!!!!
Roger

[steelcomp]

Simple and obvious first. What opens and/or closes the valve?

[Old Guy]

The butterfly valves are "off center". That is to say that the shaft the rotating plate is mounted on, is not centered on the plate. The water pressure pushing against the plate will then open the valve. A simple lever arm attached to the shaft can be attached to a spring (sorry jer) that can be tensioned to work against the force of the water to hold the valve closed. More spring = more water pressure. You could also use a small air cylinder connected to a small adjustable pressure supply tank so that you could adjust the intake pressure from the driver's seat. Both sides are the same and require the same attachments.
Roger

[LVjetboy]

"Wake me up when you post something worth reading."
Actually my posts are worth reading...and...I put a lot of thought into what I post.
"So Jer, what's your idea here on the perfect pop off valve, or device to control the unwanted overcharge?"
I've already mentioned, but again, here's what I think...
1) Structurally designed to a safety factor. This basic engineering as I'm sure you know. In other words, not just using existing bolts adapted to an application for which those bolts are not designed to handle in the first place. If that you're asking for failure. Reported bolt failures hint this is the case with some designs used now.
2) Reliable trigger point. Hard to do. If pressure sensor driven, then calibration and installation is an unknown factor. And calibration...how to do that? Even if you have an accurate pressure trigger point, then do you know what pressure to set depending on your speed and hull shutdown characteristics? Doubtful. But if you eliminate errors or inconsistent trigger caused by faulty or leaking cheap pressure sensing lines...then you got a better shot at an accurate or at least repeatable trigger.
3) Variable release and/or auto reset. I know I know, bp says rules don't allow. But common sense says the ideal popoff is not on-off. But variable with auto reset. Rates can be controlled by damping similar to a shock absorber or electronically. Been done in the car field. I'm not talking rocket science or high dollar here. Just what is possible within the cost of current popoff technology.
Manual trigger? Although ok by the rules, a safety feature of limited benefit in my opinion. Ya sure you can trigger it before you ease off the throttle during a normal slow down. But do you really need it then?? And who out there can react quickly enough to sudden engine seizure to trigger the manual before you hook and swim? Anyone?
Just curious. But rules are rules.
jer

[LVjetboy]

Old guy, I like your idea because it's an add-on feature. Not a big mod to the existing intake and actually may benefit some hulls with more setback.
"You could also use a small air cylinder connected to a small adjustable pressure supply tank so that you could adjust the intake pressure from the driver's seat."
I also like yours and Marks idea because it's adjustable and can automatically reset. A BIG plus for lake and maybe even race but against the rules according to bp. Still...makes a h*ll of a lot of sense.
Valve seal design will be challenging...other than that...cool.
jer

[steelcomp]

The butterfly valves are "off center". That is to say that the shaft the rotating plate is mounted on, is not centered on the plate. The water pressure pushing against the plate will then open the valve. A simple lever arm attached to the shaft can be attached to a spring (sorry jer) that can be tensioned to work against the force of the water to hold the valve closed. More spring = more water pressure. You could also use a small air cylinder connected to a small adjustable pressure supply tank so that you could adjust the intake pressure from the driver's seat. Both sides are the same and require the same attachments.
Roger
What effect do you think the added piece to the bowl will have on the flow characteristics of the pump? This system appears to be after the impeller, or would you require an extension for the shaft? I thought we were trying to control intake pressure?

[steelcomp]

Springs break.

[billet racing]

I should not be too difficult for a jet manufacturer to add support spots or side vents of even change the hand hole to meet the needs of a pop off.
So how about it, Agressor, Berkeley, any one willing to provide test pieces to those of us who are willing to do your testing for you?

[steelcomp]

The thing about the hand hole is that by adding a pop off valve, you're not increasing pressure. If the hand hole can hold a cover, it should be able to hlod the pop off. I believe the problem with the current design pop off is the sliding valve that acts like a slide hammer, not where or how it's attached. I like unchained's design, and possibly using some sort of electronically activeted valve, like an automatic sprinkler valve (just the design idea, not the actual valve) or something similar. I believe the valve needs to be posatively controlled through an actuator of some sort, not pressure activated against a spring, or a free floating piston.

[Old Guy]

This requires a longer shaft. It's all ahead of the impeller. I don't think it would make much difference to the flow of the pump, why would it, as long as the intake has the correct pressure in front of the impeller, it should pump water. You could use an old NG bowl for material to make the spacer.
As far as legal is concerned, I don't see a problem. The lever that operates the butterfly can be attached to a spring (or air cyl) in such a way that a high pressure "spike" would cause the lever to cam over center and lock. It would remain in that position until somebody manually reset it.
SPRINGS BREAK!!!!
Sure they do. When was the last time you broke a valve spring on a non-high performance engine. How about the springs on the suspension of your vehicle. Probably go through lots of those. Considering the thousands of springs that are used in the stuff you use and see used every day, how many have you seen that didn't work because of a busted spring.
Any "pop off" type device is going to bring with it problems. It's going to be a high maintenance gadget that's going to sooner or later "bite" whoever depends on it. That's exactly why I wouldn't waste my time trying to make a better one. After spending 40+ years designing machinery, you develop a sense of where not to go. I'm not going there.
I have no idea why you guys are hung up on "pop off" type valves. What is there about controlling the pressure that bothers you?
Roger

[steelcomp]

This requires a longer shaft. It's all ahead of the impeller. I don't think it would make much difference to the flow of the pump, why would it, as long as the intake has the correct pressure in front of the impeller, it should pump water. You could use an old NG bowl for material to make the spacer.
As far as legal is concerned, I don't see a problem. The lever that operates the butterfly can be attached to a spring (or air cyl) in such a way that a high pressure "spike" would cause the lever to cam over center and lock. It would remain in that position until somebody manually reset it.
SPRINGS BREAK!!!!
Sure they do. When was the last time you broke a valve spring on a non-high performance engine. How about the springs on the suspension of your vehicle. Probably go through lots of those. Considering the thousands of springs that are used in the stuff you use and see used every day, how many have you seen that didn't work because of a busted spring.
Any "pop off" type device is going to bring with it problems. It's going to be a high maintenance gadget that's going to sooner or later "bite" whoever depends on it. That's exactly why I wouldn't waste my time trying to make a better one. After spending 40+ years designing machinery, you develop a sense of where not to go. I'm not going there.
I have no idea why you guys are hung up on "pop off" type valves. What is there about controlling the pressure that bothers you?
Roger
Roger, I've been saying throughout this whole topic that I believe there needs to be a system that continually regulates the pressuer, thereby eliminating the need for a "sudden dump".
My ol' man tought me a LONG time ago, that if there's a spring in a design, more likely than not, it'll be the spring that fails. He's a pretty sharp design engineer himself, (retired, now at 73) so I took that to heart. I was just saying that it dosen't look like the hand hole is the weak link in the design, pop off or other.
I know the relation between the impller and the bowl is critical, and the extension would have to have the same wear ring and relationship to the impeller as the intake. That's a much smaller dia than the ID of a piece of another bowl.

[Old Guy]

Think of a spacer with a hole in each side. It's the same diameter as the bowl outside. The inside is like a pipe. The outside wall thickness is whatever it is.....like about an inch or so. If you used an old bowl, you cut the vanes out. The wear ring position doesn't change, other than moving back with the bowl that it's in so as to make room for the spacer. The pump shaft needs to be longer between the impeller and the thrust bearing.
jer - It's not a pop off valve. It doesn't "seat" like a pop off valve. Water will be coming through it most of the time. It will depend on what your shoe depth is set at. The "over charge" just blows out the relief instead of jacking the pressure way up.
The only time springs break is when they are not used properly or they are defective. Today's springs very seldom break. Like way less than 1 in a million. Think about it.
Roger

[steelcomp]

Think of a spacer with a hole in each side. It's the same diameter as the bowl outside. The inside is like a pipe. The outside wall thickness is whatever it is.....like about an inch or so. If you used an old bowl, you cut the vanes out. The wear ring position doesn't change, other than moving back with the bowl that it's in so as to make room for the spacer. The pump shaft needs to be longer between the impeller and the thrust bearing.
jer - It's not a pop off valve. It doesn't "seat" like a pop off valve. Water will be coming through it most of the time. It will depend on what your shoe depth is set at. The "over charge" just blows out the relief instead of jacking the pressure way up.
The only time springs break is when they are not used properly or they are defective. Today's springs very seldom break. Like way less than 1 in a million. Think about it.
Roger
The wear ring isn't in the bowl, it's in the suction housing. The spacer will have to be designed to accept the wear ring and keep it at the same relationship to the impeller as normal.

[Old Guy]

Duh!!! You're right. I have a converted Jacuzzi and it's a little different. OK, so it's a little more complicated....maybe.
I'll take another look at plan B.
Roger

[steelcomp]

Duh!!! You're right. I have a converted Jacuzzi and it's a little different. OK, so it's a little more complicated....maybe.
I'll take another look at plan B.
Roger
Not more complicated, just a little more involved. I don't see a problem with it as long as the tolerances are kept fairly tight. Concentricity and parallel/ perpendicular are going to be fairly important. It (the spacer) should probably be doweled or indexed somehow as not to depend on the clamping force of the bolts (which are now a lot longer) to keep things from rotating.
Please keep us posted.

[LVjetboy]

"The thing about the hand hole is that by adding a pop off valve, you're not increasing pressure."
No, I never posted you will increase pressure by adding a popoff. In fact, I'd expect pressure the same. But maybe you'll increase force and stress on the bolts? As you later post...
"I believe the problem with the current design pop off is the sliding valve that acts like a slide hammer, not where or how it's attached."
Yes slide hammer shock loading can certainly increase stress on attachment bolts. As well as side forces caused by venting pressure non-uniformly and the flow associated with that.
Excuse me?
Those facters affect both how and where the vent's attached...as well as attachment bolt design. And if not accounted for, well maybe some failures? But why not design for anticipated "slide hammer forces" instead of blindly using existing bolts designed for a different application?
So yes, a popoff can put more stress on freakin' stock attachment bolts you think? Regardless of the fact that intake pressure is the same... :sleeping: :sleeping: :sleeping:
Just basic engineering no big deal.
jer

[Cs19]

Concentricity and parallel/ perpendicular are going to be fairly important. .
For sure. The spacer would need some kind of a register where the bowl attaches, and it would need to recieve the register off the suction.
Not sure where wear rings come into play here. :squiggle: Must be overlooking something.
If Im understanding the concept here, the bowl veins will be much further away from the rear of the impeller due to the spacer.
That just might affect the jet pump more than you realize.

[cyclone]

I think Chris is right. Moving the bowl veins several inches away from the impeller exhaust blades would definately affect pump performance. By doing so I think you are giving the water a chance to go in different directions instead of directly into the bowl veins. Seems like it really hurt performance to me. Then again, i'm no engineer and I'm only trying to imaging what the water does as it moves from the back of the impeller to the bowl. :D

[Unchained]

For sure. The spacer would need some kind of a register where the bowl attaches, and it would need to recieve the register off the suction.
Not sure where wear rings come into play here. :squiggle: Must be overlooking something.
If Im understanding the concept here, the bowl veins will be much further away from the rear of the impeller due to the spacer..
Rogers design has the impeller and the bowl moved back farther and the additional bowl spacer in front of the impeller with the wear ring in it.
The impeller and bowl would be the same distance apart as original, just spaced back a few inches.
It would be a bolt on unit.
What caught my attention is the fact that you could add a second inducer in front of the impeller or a similar device to get the water moving from a dead stop. Also you could add multiple vent points if needed in the spacer.
I would not be afraid of a spring at all.
How many millions of cycles do engine valve springs take? And that's a severe usage.
As far as the butterfly valve the off center location of the shaft and the balanced design will be the key to not needing a real large spring.
I think we need to dump the term "popoff" and use the term "regulator"

[bottom feeder]

Mark and Roger,
Looks like an original to me, hell you could even through in a pressure probe point. Let me know if you need anything.
Brian

[Old Guy]

Good grief!!! It never ends. My head is just spinnin now.
Here's the new economy model. Haven't detailed it yet. Gotta take care of some chores first.
http://files.triton.net/old1/boat_berk1c.jpg
Roger

[Old Guy]

OK here's the plan. Everybody likes the hand hole. It's there. It's cheap, and it's big enough to do the job (probably).
The plug is removed from the hand hole and the device in the pic is bolted on. It's a tube with a butterfly valve. The butterfly plate is mounted slightly off center so that the water pressure will open the valve. There is a lever attached to the butterfly shaft and a spring (adjustable) or a small air cylinder is attached to the lever. This applies force to hold the valve closed. As the intake pressure increases, the valve is forced to gradually open and maintain a preset pressure in the intake. On the opposite side of the device is connected a potentiometer which is connected to a trim indicator. The trim indicator shows how far the relief valve is open. A relief valve that is very far open to maintain the proper intake pressure would indicate too much shoe depth.
http://files.triton.net/old1/boat_berk2c.jpg
Again.......IT'S A CONCEPT DRAWING
SOCK IT TO ME!!!
Roger

[cyclone]

that looks pretty promising. How much do you estimate the parts would cost to put the system together?

[billet racing]

One problem I forsee is an air pocket in the system. This would cause a cavitation at the start line. You would have to purge the air out of the system.

[bottom feeder]

Could just cycle the valve once before startup? Indicator would verify function.

[Old Guy]

The first one would take some time to define the values for some of the components. (I know jer, that's not very scientific) I think it shouldn't cost much for the material to make one. A few hours to do some more design work. A couple days to build the thing and who knows (a few hours in a boat tinkering) how long to refine it.
I think the concept is solid and the device is simple. It should work and be pretty much maintenance free. If it did fail, it would fail "safe".....nobody gets hurt.
Oh, as far as trapped air is concerned. A small hole in the butterfly plate would bleed off any air. As soon as the motor is started, a blast of water will hit the butterfly and I doubt any air will be trapped. This assumes the use of an inducer.
Roger

[steelcomp]

OK here's the plan. Everybody likes the hand hole. It's there. It's cheap, and it's big enough to do the job (probably).
The plug is removed from the hand hole and the device in the pic is bolted on. It's a tube with a butterfly valve. The butterfly plate is mounted slightly off center so that the water pressure will open the valve. There is a lever attached to the butterfly shaft and a spring (adjustable) or a small air cylinder is attached to the lever. This applies force to hold the valve closed. As the intake pressure increases, the valve is forced to gradually open and maintain a preset pressure in the intake. On the opposite side of the device is connected a potentiometer which is connected to a trim indicator. The trim indicator shows how far the relief valve is open. A relief valve that is very far open to maintain the proper intake pressure would indicate too much shoe depth.
http://files.triton.net/old1/boat_berk2c.jpg
Again.......IT'S A CONCEPT DRAWING
SOCK IT TO ME!!!
Roger
Now yer talkin!

[Old Guy]

Funny thing is.....I don't have a Berkley type intake. Mine is a Jacuzzi with a huge hand hole. Not that it matters. The hand hole is inside the boat. I guess if I build one of these, it will have to be for somebody else's boat. Real inconvenient.
Roger

[ARS Marine inc.east]

I see alot of cavitation . Being the Valve being so High.

[Old Guy]

Only one way to find out.

[ARS Marine inc.east]

Sounds Like a Plan.

[steelcomp]

Funny thing is.....I don't have a Berkley type intake. Mine is a Jacuzzi with a huge hand hole. Not that it matters. The hand hole is inside the boat. I guess if I build one of these, it will have to be for somebody else's boat. Real inconvenient.
Roger
Roger,
I think I could talk a friend ouit of a Berk suction piece that's been welded at the bearing support, but probably never going to get used. I could send it your way for a mock up.

[Old Guy]

You send it. I'll make one. I will need to work with somebody local for the tinkering part. Maybe I can get Mark to try it on his boat.
If it works the way I think it will, when it's finished, I'll post all the specs. and info that's needed for whoever wants to make their own, to do it.
If you're interested, PM me.
Roger

[Unchained]

My boat can be used for a floating guinea pig.
Any part that would fit a Berkeley wouldn't fit a Dominator though unless there was a multi bolt pattern ring . Berkeleys have two bolts and Dominators have three.
A negative I can see from venting through the hand hole is that the opening may be a deterrent to the internal pump flow.
I haven't looked at a current model popoff to see what the bottom of the valve looks like.
Does it match the contour of the inside of the pump in the closed position ? Maybe someone else has some input there.
As with the trial of the duct I made any new parts need to have some kind of documentation that users can understand. A before and after thing.
It would be easy to video the intake pressure gauge and watch the stability of the pressure through a run.
I don't think it will be a factor of any leakage around the butterfly valve.
Any leakage would be a tiny fraction of the huge volume that's going through the pump.

[ARS Marine inc.east]

Should Be Able to post some Pics For ya later tomorrow,
Battrey is Dead In the Camera, Need to buy a new one!
Everything Takes a Chit after Christmas
We carry a Miersch Popoff
Along with the NEW Saftey Restreint Bag that is made to Fit.
The Kit comes complete with, Co2 tank, lines,Regulator and Popoff,
The NEW Saftey Rastreint Bag Sell's for only $100.00
Thats alot Cheaper than Purchasing a New Popoff, That goes to the Bottom of the Lake Or River!
Sorry it took so long to Post Pics
Batterys for these old cameras Needed to be Special Ordered.
Here are a Few Pics of the Miersch popoff Latest Design.

[Duane HTP]

Interesting. The butterfly would have to seal very tightly, or there would be a severe cavitation problem from sucking air on initial take off before the boat was moving fast enough to build intake pressure. Computer print outs always show a period of suction right on take off until the boat is moving fast enough to pick up enough water to make pressure. Just a thought to deal with.

[Old Guy]

Thanks Duane,
Can you share some of that data with us? How much suction, for how long?
Do present pop-off designs provide a smooth surface down inside the pump for water to flow against? The pic posted by ARS shows a projection with a angular profile, however I thought it would need to extend down further into the pump to be flush inside. What's the story?
I really don't see a problem sealing the butterfly. If they can make a Wankel work, that butterfly shouldn't be too difficult.
The off center design of the butterfly causes suction to close it, pressure to open it.
Any and all comments and suggestions are welcome here. Thank you.
Roger

[ARS Marine inc.east]

When installled there is a Smooth Transitition like the Hand hole Covers We make.http://www.***boat.com/image_center/data/500/1937ARSCustomfithandholecoverMA8985628
That Was the reason for My comment about the Cavitation Issues with the Valve Being so high.

[Duane HTP]

Yes, the pop-off piston does make a smoothe transistion across the hand hole outlet.
Depending upon the available HP, the instant the throttle is cracked open, the pump goes into a short period of suction because the impeller tends to unload the pump by emptying the throat of it. This is what the inducer is all about. It shortenes this time. It fills that throat back up quicker so that the impeller is not running in a vacuum. Once the pump goes into suction, or creates a vacumn it spins freely and starts slipping. Last year, by shortening the amount of time that the pump was in the suction mode, we bettered our ET by .2 of a second.The last few runs last year, we had the suction time down to about 3/4 of a second or under. I just brought this up, because a vacumn leak at the butterfly would lengthen the time it took to refill the throat of the pump, just like a leaking packing affects the suction period on take off. In simple terms, If the pump can suck air instead of water, you're spinning your impeller, (wheels). Hope this makes sense. Not trying to be critical, just trying to help.

[Old Guy]

I see this as constructive criticism, not in any way offensive. If anything good is to come from this, it is necessary to question things that have been considered stuff that "everybody knows". For example, after reading many posts made by a great variety of people, I have come to the conclusion that, under "race conditions" suction pressure jumps around a lot. I can go from vacuum to enough pressure to blow the pump apart. I see fine tuning shoe depth (with very thin shims) to get everything "just right".
It seems to me that in order to avoid any possibility of cavitation, it's necessary to over-charge the pump intake. This becomes a very delicate proposition as too much intake pressure leads to all kinds of problems. If the impeller stops turning suddenly while running at high speed, the water has no place to go, so it seems to create some sort of large lump under the pump intake, which raises the rear of the boat, which lowers the front of the boat, which at 100+ mph can be big trouble.
So.......I come to the conclusion that if the pump can be over-charged slightly, and the excess water relieved through a valve, two things will happen. First the intake pressure should be stable (as in no spikes), Second, if the impeller stops turning, the water just blows through the valve.
In addition, if the pump intake is covered (as in the mod on "Unchained's" boat), it seems to me that it's very unlikely that a "lump" is gonna form under the intake....no matter what happens. Mark has got about 40 hours of run time on the setup so far.
Roger

[LVjetboy]

"What's your idea here on the perfect pop off valve, or device to control the unwanted overcharge? You've given us your analysis of everyone elses ideas, but how 'bout your own?"
Sure no problem. I've never seen the current popoff design, but I'll be happy to post a design.
jer

[Unchained]

If no air space is a concern then the "below the waterline" setup I posted a picture of would be an advantage.
Nothing but a piston is going to have a perfectly smooth internal flow though.
Then you have an air powered slide hammer / projectile launcher.
" TO DA MOON ALICE "
I'm not sure that the smooth internal flow is that much of a factor when you're already scooping more water than the pump can flow out the 3.125 nozzle.
The volume of water being forced into the pump that it can't pass reminds me of the effect you get when you aim a pressure washer into a corner.
Comes right back out at you with the same force.

[Squirtin Thunder]

Can any of y'all that have pop-offs post pictures of them inside and out? I am wanting to learn more about them as far as who all makes or made them, which ones are manual, which are automatic or both manual and automatic. On the automatic ones, how are they triggered, RPM switch, pressure triggers and so on. I would love to hear what you guys that have them and have run them have to say about the different options and styles of valves,and who you think made the best one and why. I would also like to see some good pictures of valves both on and off the pump if y'all have them. Also, do any of y'all run them on double duty lake/race boats like mine will be, and if so do you disable it while at the lake, or just set it up to be manually fired when at the lake/river?
I will be running one of HTP's Jet-A-Ways on my boat and might also run a pop-off when we go to the track if we step up into some bigger numbers from where we hope to start.
Anybody got one for sale????
Anything this guy says is bullshit !!!!