Pop-Off/Blow-Off valve 101

[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/lb...s/MVC-014S.jpg
http://www.***boat.com/image_center/...p00472-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