Re: Pneumatic Regulators from Automation Direct
 

For those who are following here but don't check the Q&A, this was not answered by close of business on Friday.

Re: Pneumatic Regulators from Automation Direct
 

Just a quick response here and then I will be quiet for a couple of days again while traveling.

R77. H. Shutoff valves which relieve downstream pressure to atmosphere when closed (may also be known as 3-way or 3-way exhausting valves).

While these are now legal, they have not been allowed or legal in the past. Each manufacturer has a different name for them, (thank you marketing people) they are what I believe the discussion is about.
The Bimba part linked above is one of the devices that I believe influenced the addition of this rule. It is a 3-way valve in that air at one port is directed to another port to move the cylinder. When air is removed, the pressure in the cylinder is directed to atmosphere at the third port. The Bimba spec sheet gives an example of a method to move a double acting cylinder with a two way control valve and two of the linked valves.
Check valves have also been included in R77.G if and only if R89 can be satisfied. The Bimba device will exhaust all stored air when system pressure is removed.

Re: Pneumatic Regulators from Automation Direct
 

Thank you Automation Direct for the free pneumatic components! With this and PDV, we've gotten nearly $100 of free, high quality components from AD just this season. Thank you!

-Mike

Re: Pneumatic Regulators from Automation Direct
 

Got our free gear as well! Thanks Automation Direct!

-Brando

Re: Pneumatic Regulators from Automation Direct
 

Team update 15 has completely settled the quick exhaust debate by properly updating the wording of R77 G. to include Check and Quick Exhaust Valves. Thank you GDC for taking the ambiguity out of this rule.

Re: Pneumatic Regulators from Automation Direct
 

Thanks again for the parts, they'll be on the next iteration of our machine!

Re: Pneumatic Regulators from Automation Direct
 

We received our free parts and will be ordering more shortly with our voucher! These parts are very high quality and we look forward to do business with you guys in the future, thanks Automation Direct!

Re: Pneumatic Regulators from Automation Direct
 

We too received ours. Thanks Chip and Automation Direct!
Nate

Re: Pneumatic Regulators from Automation Direct
 

Anybody notice Q963? In the answer, the GDC states:
This doesn't fit any of the definitions or descriptions of check valves I've ever seen. Does anyone know of an item which meets this description and is sold as a check valve?

Re: Pneumatic Regulators from Automation Direct
 

Gus,
The valves asked in the question are sometimes called 'check valves' but vent to atmosphere when the pilot pressure is removed. They are actually "quick exhaust" valves or "three way" valves depending on manufacturer.

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