Re: Pneumatic Regulators from Automation Direct
 

A check valve that is not legal is one in which air moves in only one direction. (What I think most of us believe is the true definition of check valve) That would prevent the release of all stored pressure under R89 because air would not move back through the check valve when system pressure is relieved. The three way valves will vent any stored pressure when the system pressure is relieved.

Re: Pneumatic Regulators from Automation Direct
 

Wouldn't it be legal to use a traditional check valve as long as the upstream side wasn't plumbed (thus not closing off a segment of the system). A use I could see would be an if a team used an off board compressor and used the check valve to connect the compressor (and other necessary off board hardware) to the system. A team could also use a check valve as a plug on a tube, again assuming they never plumbed the other side and closed it off from the vent valve, this would probably an expensive plug but I believe it would be legal.

Re: Pneumatic Regulators from Automation Direct
 

Using a check valve as a plug is rather like signalling with an unpowered flashlight - you're allowed to use a flashlight, but not if you use it AS a flashlight.

Using a check valve to connect a compressor is possibly illegal (not drawn that way in the diagrams, but not explicitly forbidden as far as I am aware), but is not really a good idea anyway. If you did this, you would still need vent plugs on both sides of the check valve to operate safely - one on the robot side to dump robot air when/if needed, and another on the supply side to depressurize the supply side for purposes of disconnecting.

Re: Pneumatic Regulators from Automation Direct
 

Kevin Sevick brought a better legal use of a check valve then either of my not so useful uses.

You could plumb a check valve in parallel with a regulator downstream from one side of a solenoid valve before a cylinder. In this way you could adjust the pressure on either the extend or retract side without having to exhaust through the regulator which is a slower process. This basically makes it a slightly slower quick exhaust valve since it vents to the solenoid exhaust port and straight to atmosphere.

Re: Pneumatic Regulators from Automation Direct
 

You want to use a $7 (based on AD prices for 1/4" tubing models) check valve to sort-of replace a $3 quick exhaust valve? For an on-site mod when you have to work from your parts on hand, OK. I wouldn't want to design like that.