Re: Pneumatic Regulators from Automation Direct
 

While a quick exhaust valve has a check valve in it, I would not refer the assembly as a check valve. Anymore than I would call a cylinder flow control valve a check valve although they generally have a check valve in them. Anyway. Intended or not, the way I read the rule is you can use check valves. Check valves have to be used in such a way the R89 is met & the system can be fully vented by the one vent valve. One application would be to vent closed ended portions of the system.

Team update 15 spefically amended rule 77-G to add quick exhaust valves to the allowed list.

Now that I think about it a bit... A quick exhaust is essentially a pilot operated check valve. Given the GDCs dislike of pilot operated valves, I am not sure I would ask a question to them calling it that. :]

Re: Pneumatic Regulators from Automation Direct
 

Frank,
Most of the valves I see these days are pilot air operated valves.

Re: Pneumatic Regulators from Automation Direct
 

Sorry I was a little imprecise. I didn't mean to include intergral solenoid piloted valves in the larger class of pilot operated valves. Thankfully they are legal. Otherwise the PCM would be way under powered.

Re: Pneumatic Regulators from Automation Direct
 

The question asked (emphasis mine) was:
The questioner clearly did NOT understand check valves to vent to atmosphere when the inlet pressure was removed.

In their response to Q926 and subsequent update to rule R77-G in Team Update 15, the GDC confirmed that "quick exhaust valves" and "check valves" are different things.

The question remains - does anyone market an item as a "check valve" that meets the GDC's definition of legality? If so, what is the function of said item?

Edit: Frank, I agree that a quick exhaust valve is in essence a degenerate form of an air-actuated 3-port valve that consolidates the control port and the inlet port. I agree that I would not use this terminology in a Q&A.:ahh:

Re: Pneumatic Regulators from Automation Direct
 

In 2014, we used 2 Festo valves (think it was am-0888) which worked as a 3-way valve on our intake arm. The idea was to have 3 states; up, down and neutral. Up and down force the arm into those positions. We wired the user control such that the arm would be pushed down and then switch into neutral.

This allowed the arm to raise up as the roller spun the ball into the robot. The effect was to provide for a longer time period of roller/ball contact as the roller pulled the ball in.

Dave

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.