Placing a Tank after a solenoid valve

[DonRotolo]

Consider alternative ways of 'assisting' your cylinder's extension with, say, latex tubing.

EDIT: If you place a storage tank after a solenoid valve, will THE one Pressure Vent Plug reliably vent all stored pneumatic pressure from the system when the release valve is opened? If not, R89 will be violated.

[MechEng83]

Originally Posted by DonRotolo

Consider alternative ways of 'assisting' your cylinder's extension with, say, latex tubing.

EDIT: If you place a storage tank after a solenoid valve, will THE one Pressure Vent Plug reliably vent all stored pneumatic pressure from the system when the release valve is opened? If not, R89 will be violated.

The pneumatic valves from FIRST Choice last year (and possibly this year, as I don't have access due to school STILL being closed... ) violate this rule. The valves have a neutral position, which means that unless the solenoid is active, the pressure from both sides is dead-headed. This is different behavior from the KoP valves from several years ago.

[KevinG]

Originally Posted by DonRotolo

Consider alternative ways of 'assisting' your cylinder's extension with, say, latex tubing.

EDIT: If you place a storage tank after a solenoid valve, will THE one Pressure Vent Plug reliably vent all stored pneumatic pressure from the system when the release valve is opened? If not, R89 will be violated.

Why would the amount of air located on one side of the solenoid valve matter? There's 60 psi of air contained within the tubing, and that has to vent just as reliably as air contained in accumulators.

[ToddF]

It's our opinion that as the rules are written, an accumulator downstream of the solenoid valve is legal. If a QA answer rules this out, it is legal to connect multiple cylinders to a single valve. Just pick one with the internal volume of the tank you want, and plug one of the ports. Viola, instant accumulator. Not as weight efficient as a tank, but performs the same function.

Or, as someone else mentioned, pick a cylinder with a large internal volume and only plan to use half (or less) of the stroke. (This is actually the most weight efficient solution of all.)

[Al Skierkiewicz]

R89
The pressure vent plug must be:
A. connected to the pneumatic circuit such that, when manually operated, it will vent to the atmosphere to relieve all stored pressure, and
B. placed on the ROBOT so that it is visible and easily accessible.
If the compressor is not used on the ROBOT, then an additional pressure vent plug must be connected to the
high-pressure portion of the pneumatic circuit off-board the ROBOT with the compressor (see R79).

Air pressure in a storage tank is "stored" in the rule above.

[FrankJ]

So using the accumulator as described is OK as long as the vent valve will release its pressure?

[Al Skierkiewicz]

I have to ask the OP to be sure...
OP, You are using a valve to charge a tank and operate a cylinder in the same circuit? Is that what I am reading?

Madison,
In looking at your drawing, I do not see how the stored pressure can be vented immediately by opening the manually operated valve. Should there be a failure in either of the regulators, opening the valve leaves high pressure air still in the tanks. While that may have passed inspection at your events in 2012, I do not think it was legal in 2012 or now.

Please ask the question of the Q&A.

[Madison]

Originally Posted by Al Skierkiewicz

I have to ask the OP to be sure...
OP, You are using a valve to charge a tank and operate a cylinder in the same circuit? Is that what I am reading?

Madison,
In looking at your drawing, I do not see how the stored pressure can be vented immediately by opening the manually operated valve. Should there be a failure in either of the regulators, opening the valve leaves high pressure air still in the tanks. While that may have passed inspection at your events in 2012, I do not think it was legal in 2012 or now.

Please ask the question of the Q&A.

Al -- Unfortunately, pneumatics isn't my area of expertise, so I can't provide a definitive answer for your concern. I do know, however, that we were able to vent all the pressure from the system with the single release valve. I'll ask the folks who were responsible for this to provide some clarification. It may be that the system was changed after this schematic was created.

-Madison

[gpetilli]

Originally Posted by Al Skierkiewicz

I have to ask the OP to be sure...
OP, You are using a valve to charge a tank and operate a cylinder in the same circuit? Is that what I am reading?

Madison,
In looking at your drawing, I do not see how the stored pressure can be vented immediately by opening the manually operated valve. Should there be a failure in either of the regulators, opening the valve leaves high pressure air still in the tanks. While that may have passed inspection at your events in 2012, I do not think it was legal in 2012 or now.

Please ask the question of the Q&A.

I too am not an expert, but I believe the standard FRC solenoids use a supply "pilot" which means that if the input air pressure goes away (think manual dump) then the solenoid opens allowing the output air to back through the output to the input. This works only if there are no check values in the system and does not depend on any electrical signals. We have had issues in the past that if the working pressure is too low, there is not enough energy to "engage the pilot" and the solenoid does not activate. If I am correct, then this would allow the low pressure storage tank to vent when the manual release is opened.

[Mr V]

Originally Posted by gpetilli

I too am not an expert, but I believe the standard FRC solenoids use a supply "pilot" which means that if the input air pressure goes away (think manual dump) then the solenoid opens allowing the output air to back through the output to the input. This works only if there are no check values in the system and does not depend on any electrical signals. We have had issues in the past that if the working pressure is too low, there is not enough energy to "engage the pilot" and the solenoid does not activate. If I am correct, then this would allow the low pressure storage tank to vent when the manual release is opened.

Yes the common solenoids are air piloted but that is not relevant to their operation. They just use air pressure to move the shuttle, once the shuttle is moved it stays there and w/o enough air pressure they can't move the shuttle.

Since the shuttle stays in the same position the pressure on the working side of the valve can vent back through the valve. So yes tanks on the working side of a commonly used FRC solenoid will vent assuming as you noted that there aren't any check valves added into the system.

[MartyG33]

What types of tubing can we use? Can we use copper piping for our entire system if we want?

Also how do I post a new thread?

[EricH]

Originally Posted by MartyG33

What types of tubing can we use? Can we use copper piping for our entire system if we want?

Also how do I post a new thread?

Last question first: Click the big purple square in the top left of each page. Scroll down to the subforum you think is most appropriate, click it, and click the "new post" at the top of the page.


Now. The rules question.

First answer: Did you read the Manual? Your first question is answered quite clearly by R77E--and your second question will be answered by reading the rest of R77.

[MartyG33]

[quote=EricH;1332248]Last question first: Click the big purple square in the top left of each page. Scroll down to the subforum you think is most appropriate, click it, and click the "new post" at the top of the page.


Now. The rules question.

First answer: Did you read the Manual? Your first question is answered quite clearly by R77E--and your second question will be answered by reading the rest of R77.[/QUOT

Yes, but it only says functionally the same. Stiff copper would function the same as the tubing without the flexibility.

[cgmv123]

Originally Posted by MartyG33

Yes, but it only says functionally the same. Stiff copper would function the same as the tubing without the flexibility.

If you think the manual is ambiguous, that's when you ask on Q&A. Chief Delphi is not Q&A.

That said, I question your desire to use copper tubing. Copper is heavy. I'm happy to use the plastic tubing provided in the KOP, since it weighs next to nothing.

[Al Skierkiewicz]

Marty,
What Eric pointed you to is this...
E. Additional pneumatic tubing, with a maximum 0.160 in. inside diameter, functionally equivalent to that provided in the KOP