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Unread 28-08-2015, 14:53
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I am Dave! Yognaut
AKA: Brian Bray
FRC #1296 (Full Metal Jackets)
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Re: spud gun/T-shirt gun valve

Quote:
Originally Posted by GeeTwo View Post
Do not use a plastic sprinkler valve (designed for water) to switch air pressure. When the valve fails, it will explode and fragment, making this a serious safety hazard.
This is no different to using the Clippard air tanks or most other FRC actuator (electric or pneumatic) Exceed specifications and you're gonna have a bad day.

Standard water mains operate around 55-75 psi, but reach as high as 100 psi, and sprinkler valves have to be designed to function in any regional pressure condition, with safety overhead for manufacturing tolerance reasons and otherwise. Since the valve will handle 100 psi and could likely handle 120, I don't think 50-70 could be an issue.

Heck, when a sprinkler valve closes, it has to absorb all of the inertia in the flowing water as well. That just means more pressure it has to be designed to handle.

I realize that the valves aren't air rated, but that really just means nobody tried. The principle behind pressure in compressible air and incompressible water is different, but the forces at the valve are the same (psi). There is no reason it would explode at those pressures, water or otherwise.

TL;DR, if you put 300 psi behind it, yeah it will probably explode, and yeah you would get hurt. But at 70 psi, I wouldn't be worried.
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