Pneumatic Regulators from Automation Direct

[GeeTwo]

Originally Posted by GeeTwo

I just asked Q926:

I agree with Martin that the answer should be no. Check valves have two ports, QEVs have three. I don't see any way to plumb a check valve to make it into a QEV, either.

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

[Al Skierkiewicz]

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.

[Michael Corsetto]

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

[Brandon Holley]

Originally Posted by Michael Corsetto

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

Got our free gear as well! Thanks Automation Direct!

-Brando

[AllenGregoryIV]

Originally Posted by GeeTwo

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

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.

[jwfoss]

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

[Richard.Varone]

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!

[silverD]

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

[GeeTwo]

Anybody notice Q963? In the answer, the GDC states:

Originally Posted by A963

Legal check valves under R77-G will vent to relieve pressure when the inlet pressure is removed.

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?

[Al Skierkiewicz]

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.

[FrankJ]

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.

[Al Skierkiewicz]

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

[FrankJ]

Originally Posted by Al Skierkiewicz

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

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.

Q715 Q. Under rule R77 C, we have in past seasons used an air operated pneumatic valve to control our air cylinder. The valve meets the 1/8 NPT rules and at events the inspector only required that we use the specified tubing between the cylinder and pneumatic valve. To paraphrase, under R77C are rules for air operated pneumatic valves the same as solenoid valves. The part number of the valve, McMasterCarr #6124K40
FRC3451 on 2016-01-29
A. R77-C specifically allows solenoid valves (this includes both direct operated solenoid valves and the more common solenoid piloted valves). Fully air-operated valves are not allowed per R77. While we will not use this forum to definitively rule on any part, we recommend double checking the documentation for your part to determine legality.

[GeeTwo]

Originally Posted by Al Skierkiewicz

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.

The question asked (emphasis mine) was:

Originally Posted by Q963

R77.G permits Check and quick exhaust valves as long as R89 is satisfied. R89 States that a pressure vent plug must be connected to a pneumatic circuit so it will vent all stored air in a reasonable amount of time to the atmosphere. R78 also says that at least one Pressure vent plug is required, implying multiple can be used. When the check valve is used in the pneumatics system it is essentially creating an additional pneumatic circuit. Each circuit would then have their own pressure vent plug, allowing them to each be evacuated in a reasonable amount of time. Would this satisfy R89 provided each pressure vent plug is easily accessible (preferably next to each other) on the robot and can be vented releasing all air into the atmosphere in a reasonable amount of time?

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.

[DaveL]

Originally Posted by bachster

If using these, just remember that you still must meet R89:



Does anyone have an example of a useful application for the 3-way exhaust valve?

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