simple safety valve question....

[sharpshooter]

Lets say i have one of those pop off safety valves between 2 chambers. if it is set at 50 psi, it will make for a 50 psi difference between the chambers, not that it will limit the one to 50 psi correct? i.e. if one chamber is 300 psi, the other will be 250 psi?

i just wanted to clarify so i don't end up doing something stupid.

[potatoflinger]

No, If you have a safety pop-off valve set for 50 PSI, the max pressure you can have in either chamber is 50 PSI, because any higher than that and the safety valve will open.

[sharpshooter]

i guess thats not what i was going for... lemme try to explain differently.

If i have one chamber hooked up to a regulated source at 300psi, and another chamber connected to it via the safety valve the opens at 50 psi, will the 2nd chamber eventually reach 300 psi, or will the safety valve close back up once the pressure difference of the 2 chambers is less than 50 psi?

[Pilgrimman]

You have a chamber at x psi. and a popoff valve connected to the chamber that opens at x+y psi. If the popoff opens into another chamber, the first chamber will always be at y psi more than the second chamber. Ex. Chamber 1 at 300 psi. assuming everything is at equilibrium, chamber 2 will be at 250 psi if the popoff triggers at 50 psi.

The only problem I could see is if the area acting on the popoff valve is greater on the chamber 1 side than the chamber 2 side. It's the same principle as a piston valve i.ae. different areas at equal pressures exert different forces. You will have to try different popoffs and dial in the pressures if you want certain pressure differences. From your post, it seems you are trying to use a popoff as a regulator. This would work, but the popoff can't be adjusted.

[potatoflinger]

If I am understanding correctly you are just trying to have one chamber at 300 PSI and one chamber at 250 PSI, so why not just use a regulator between the two chambers to regulate the 300 PSI down to 250 PSI?

[sharpshooter]

the biggest reason is size. i found some adjustable pressure ones that are about 3/4 in long and 1/2 in dia. the other is that if i can spend $8 instead of $40 im all for it, even tho $30 is really that big of a deal.