Check valves that trigger at a certain pressure?

I’m looking for a valve similar to a check valve but will allow air to flow through once the system reaches a certain air pressure. Is there such a valve that egisists? If so are the FRC legal?

I think what you’re looking for is called an adjustable check valve. Here or here

As for their FRC legality, standard “rules aren’t out yet” disclaimer. Under the previous rules you may have been able to consider them a check valve (R77 G), or perhaps a “passive flow control valve” (R77 F).

That would be a considerable stretch of the rules. If the rules this year read like last year’s that would definitely be a Q&A item. If the Q&A ruling is (for example) “yes, an adjustable check valve is a check valve”, then you would have strong documentation to support your claim at inspection, and you could expect uniform application at different events. LIkewise, if you get a “no” ruling, you should be able to expect other teams not to be able to use them either (though of course, things get missed).

The pneumatics rules in recent years have been such that nothing is allowed unless is specifically listed as allowed in a pneumatics rule. (In contrast to most mechanical items such as arms or gearboxes, which are allowed unless there is a rule which excludes them.)

There is actually a check valve in the output of many of the legal compressors. It is required for operation. However, in all cases, COTS pneumatic parts must allow all stored pressure to be released when the Pressure Vent Plug Valve is operated.

What you are looking for is called a back pressure valve. The simpler ones are essentially a check valve with either an adjustable spring tension or preset to open at the desired pressure. “back pressure valves” were not a listed legal component under 2016 rules. “Check valves” were listed components and legal under 2016 rules. A definition thing. In any case it would have to be plumbed to meet the other rules, as Al said. The relief valve required on the robot is actually a check valve with adjustable opening pressure.