Valve that shuts off once a set pressure is reached?
For something I am in the process of designing, I need a valve that can be connected to a high pressure source and will allow the gas from the high pressure side to to flow into a sealed container on the other side until a pre-set pressure is reached. It should then shut off.
The system used to do this should also be able to handle a very high pressure spike (possibly even the type of compressed pressure wave generated during a super-sonic combustion / detonation) on the sealed container side.
If you can provide a diagram or the name of a type of valve or even just a description of how this could be done it would be appreciated. No computer controlled stuff please.
##################### The answer I have discovered is to use a regular diaphragm-type pressure regulator. ######################
Discussions
8 years ago
another "try to guess what I'm doing, then tell me how to do it question". if you use a gas regulator you will achieve until a pre-set pressure is reached.
but a detonation is going to break something.
what are you making?
L
Answer 8 years ago
A gun powered by a gasseous fuel mixture.
8 years ago
Be sure and film the operation once you build it. It'll look great on youtube and it'll be good evidence in the trial.
Answer 8 years ago
The trial?
Answer 8 years ago
Sure. When this thing blows up and the survivors ask for damages from the estate.
Answer 8 years ago
Haha yeah that would be a problem. But for future reference, there are no survivors. I think you underestimate the strength of steel. I have built and tested 4 prototypes of the gun this will be going on already and there has not yet been any injuries or serious property damage associated with them.
Answer 8 years ago
I'm not sure I find "there are no survivors" reassuring. [grin]
However, "it hasn't blown up yet" is not, by itself, sufficient evidence that it won't blow up next time -- there may be a flaw in the material, or a bad connection, or a backfire to your fuel source, or something else that takes it over the edge. And after repeated firings, metal fatigue may make that more likely. High-velocity explosions can put one heck of a lot of pressure into a small area; any flaw is likely to become progressively worse.
If you aren't absolutely sure you know what you're doing, I would recommend being a safe distance away and behind a stone wall when you trigger this thing. It may work perfectly ten times and take your arm off the eleventh.
Answer 8 years ago
Thanks for the advice. I am sure I know what I'm doing though. And I'm don't just jump to pumping pressurized HHO gas mix into the combustion chamber and pulling the trigger either. A new gun is tried with butane and/or propane and air mix, then hydrogen / air, then HHO (I've only tried HHO once and it was on my newest gun, version 4). The next gun (version 5) will be the first with a pressurized combustion chamber though. There is an element of danger in a lot of things we do. You risk you life on every car ride. Personally I have the balls to test these things. The wall is a good idea though. I will probably just take advantage of curvature of the ground instead of building a stone wall.
8 years ago
. If you don't need a lot of flow, use a long length of small-diameter piping/tubing between the impulse point and the regulator (you may want to add a pulsation damper near the regulator).
Answer 8 years ago
The small pipe idea could help protect the regulator, but the entire flow of gas needs to happen in a fraction of a second. What is a pulsation dampener?
8 years ago
I can't see any regulator accepting an overspike like you describe without rupturing. You need to isolate the regulator once you have pressurised the chamber.
Answer 8 years ago
Well yeah I could just put a specially built check valve between the main valve and the container.
Answer 8 years ago
From your description, I wasn't convinced that a check valve would close quickly enough.
Answer 8 years ago
The explosion won't happen immediately after the pressure is reached, there are a few more mechanical things that happen first. Also, I can use switches that won't let the electric igniter cicuit fire until the entire mechanical cycle is completed.
8 years ago
This sounds like a question to take to an expert. There are people who know, but the odds of getting correct advice free on a random website for so specific (and safety-related) a question are pretty low.
Answer 8 years ago
I can design something myself if I have to, I just figured that I might as well ask if something already exists that I can copy. That's easier than designing a new thing sometimes.