pic: In-Line Pneumatic Fittings

[Conor Ryan]

Originally Posted by Kevin Sevcik

These don't pass R66, unless we ignore the parenthetical "(specifically "needle valves")". I wanted to use some last year and was shot down by the GDC:R77(F) is largely identical to this year's R66(F) except for this year's addition of "passive" and the parenthetical. So unless the GDC's interpretation has greatly changed, quick exhaust valves were illegal this year.

Mind you, I'd love if they were legal for the obvious speed increases. So if you're petitioning the GDC to update the regulator part of R66, you might want to add that as well.

I'm not so familiar with quick exhaust valves, why would they be ruled unsafe?

[Oblarg]

Originally Posted by Conor Ryan

I'm not so familiar with quick exhaust valves, why would they be ruled unsafe?

A good question that has never been adequately answered, especially given the fact that it's legal to just not put a fitting in one end of a dual-stroke cylinder and vent directly to atmosphere that way.

[rfolea]

Originally Posted by Oblarg

A good question that has never been adequately answered, especially given the fact that it's legal to just not put a fitting in one end of a dual-stroke cylinder and vent directly to atmosphere that way.

Some folks disallow quick exhaust valves because they are technically "Check Valves" (Only let air pass in one direction, other direction is vented) and anything that can keep a system pressurized (like a check valve) after the air has been vented to the atmosphere is illegal, since we don't want ANYTHING left pressurized when the system has been opened up, for obvious safety reasons.

The problem with this argument is the QUICK exhaust valves actually make the system SAFER in that they GUARANTEE the system won't be pressurized.

Yes, we are working on the wording of that one too ... Sometimes common sense HAS to win ...

BTW - all the solenoid valves folks use that have a center closed position are ALSO illegal under this rule (they can keep a system pressurized after venting), but no one seems to notice that ...

[Kevin Sevcik]

Originally Posted by rfolea

BTW - all the solenoid valves folks use that have a center closed position are ALSO illegal under this rule (they can keep a system pressurized after venting), but no one seems to notice that ...

Closed center solenoid valves would actually probably fall under R78(A):

Any 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 in a reasonable amount of time.

Whether they're legal or not depends on if you think the air inside them constitutes "stored" pressure, "working" pressure, stored pressure, or some other kind of pressure. The pneumatic rules use several different terms when talking about pressure on the robot, so I don't think it's clear if they want the the entire system at ~0 psig with the vent open, or if they just want the tanks at ~0 psig.

In other news, the pneumatics rules are kind of arcane and vague and could really use some revising to better clarify and enforce whatever the GDC's intent behind them is. There's some hint of an intent to limit actuator speeds and unintentional overpressure from external loads on cylinders, but it'd be better if they spelled that out up front.

[The Lucas]

Originally Posted by Conor Ryan

I'm not so familiar with quick exhaust valves, why would they be ruled unsafe?

FRC rules are not necessarily implying that they are unsafe. R66 is a prescriptive rule listing the only pneumatic components which are legal. If it doesn't fit in one of those categories then it is illegal. Check valves are also illegal according to the Q&A. My speculation is that FRC wants limit the types of valves to solenoid valves (ultimately controlled by the on the RIO firmware), relief valves (prevent over pressure on compressor) and pressure vent plug valves (each has to be capable of venting all pressure on their own, not in combination with other valves like quick exhaust valves) so that it is easy for inspectors to verify that the system is safe & under control. Probably the most time consuming part of the inspection process is verifying pneumatic operation (especially testing the setting of the relief valve) and verifying the operation and orientation of quick exhaust valves or check valves would only add to the time and complexity of inspection.

Originally Posted by rfolea

#12: R66G - This really only applies to the primary regulator which HAS to be the KOP regulator (and is limited to 5-50psi). These should only be used DOWNSTREAM of that. Just like all the other regulators we typically use. Yes, I know the rules don't explicitly say that - we are talking to FIRST about the wording of that rule because it doesn't make any sense as stated...

The primary regulator doesn't have to be the KOP Norgren one, the blue box under R71 recommends 2 different part numbers, but those are not the only ones that can be legally used. The Monnier data sheet has output data for over 60 PSI but it must be adjusted to no greater than 60 PSI on a robot.

Originally Posted by rfolea

Shut Off Valves - 2 and 3-way shut off valves - the 3-way valves relieve downstream pressure so you can shut off a subsystem and release pressure at the same time. Very handy. (HVU14-2, HVU14-3)

R66B requires pressure plug vent valves be functionally equivalent to the (2-way) KOP valves, so I am not sure 3-way valves would be meet that requirement (probably should ask next years Q&A, or try to get the rule changed for next year). I agree they would be useful (especially this year for removing cylinders to fit into transport configuration).