Quick Exhaust Valves - Illegal !?!?

[sanddrag]

I am extremely disappointed and frustrated by this Q/A ruling: https://frc-qa.usfirst.org/Question/...-per-rule-77-f

I'd argue that quick-exhaust valves are flow control valves under R77-H, because what they do as a function is control flow. They divert the flow of air from one port to another. They are a commercially produced, readily available, pressure-rated component. Okay, maybe it isn't what FIRST means by flow control (with the little knob to slow down the flow of air) but still, what's the harm?

What's the reasoning for ruling them illegal? Making quick-exhaust valves illegal completely invalidates SO many innovative designs, and limits students' exploration of the physics concepts behind pneumatic systems.

What's the history on the legality of these in years past?

Really hoping they reverse this ruling. Until then, we are out hundreds of dollars, and now redesigning our launcher....

[magnets]

That's interesting... For a while, we were thinking of using them too. They are (what I would consider) a flow control valve.

We've put these on our robots for years. I may be remembering wrong, but I think something like that may have been given in the kit in years past.

What's stopping you from getting a solenoid valve with a really high flow rate, then connecting it directly to the cylinder? Also, you'll only need this valve on the retract side, so you could go with a spring/gravity return.

[martin417]

Originally Posted by magnets

That's interesting... For a while, we were thinking of using them too. They are (what I would consider) a flow control valve.

We've put these on our robots for years. I may be remembering wrong, but I think something like that may have been given in the kit in years past.

If you have used those valve anytime since 2008 (the year I started FIRST) you were not legal. I use pneumatics in my job, and quick exhaust valve (also called quick-dump) are extremely useful, but have never been FIRST legal. Believe me, there were many years that I wanted to use them!

They are not flow control valves. A flow control valve can restrict the flow, not re-direct it.

[DavisDad]

Originally Posted by sanddrag

I am extremely disappointed and frustrated by this Q/A ruling: https://frc-qa.usfirst.org/Question/...-per-rule-77-f...

I've been disappointed too. There have been several prototypes that would have worked if the exhaust wasn't restricted through the solenoid. I guess they want to "err on the side of caution" and ensure there is some dampening of the cylinder.

If y'all haven't seen team 2073 cocking mechanism, take a look: Very clever catapult

[cmwilson13]

just dont hook a fitting up to it. let it be at atmospheric. find another way to retract it

[Bill_B]

Originally Posted by cmwilson13

just dont hook a fitting up to it. let it be at atmospheric. find another way to retract it

I think there is a fitting that vents and prevents contamination at the same time. I wouldn't leave a cylinder's retraction port open to the particle-filled FRC world.

[Ether]

Originally Posted by cmwilson13

just dont hook a fitting up to it. let it be at atmospheric.

Has anyone run that by Q&A? Ya never know...

[Christopher149]

Originally Posted by Ether

Has anyone run that by Q&A? Ya never know...

Since our prototype is currently using a fitting-less downstroke, I went ahead and asked.

[sanddrag]

I'm wondering if there exists such a thing as a "quick exhaust fitting" If so, it would be a fitting, not a valve, and thus rendered legal for use. Anyone an expert of pneumatics manufacturer's catalogs?

[jmartin]

Originally Posted by sanddrag

I'm wondering if there exists such a thing as a "quick exhaust fitting" If so, it would be a fitting, not a valve, and thus rendered legal for use. Anyone an expert of pneumatics manufacturer's catalogs?

Such a thing seems to exist, for example Clippard's JEV-F2M2 (See http://www.clippard.com/downloads/PD...Page%20162.pdf). However, I would expect that even though in they are fittings in one sense, that they might not be legal - especially since Clippard even calls them "valves". And I think (but I'm not sure since I can't seem to find that exact part number) that the quick exhaust valve provided as an example in the question that's already been asked was a fitting type quick exhaust valve too.

[DavisDad]

Originally Posted by Ether

Has anyone run that by Q&A? Ya never know...

Good point Ether! I'm working on the following Q&A's for pneumatics:

1. Can a regulator be driven by servo to make a proportional control valve (I/P)?
2. Can one of the two(2) pneumatic cylinder's ports be left open; vented to atmosphere?

[MrBasse]

Originally Posted by Ether

Has anyone run that by Q&A? Ya never know...

I'm curious to hear the answer as we have used a 90 degree fitting with no tubing to vent to atmosphere while using gravity to return the cylinder for the last two years. We used it on our ball pickup in 2012 and our climbing arms and disc dump in 2013. Both years we passed inspection at two districts and MSC.

Also, if you put the opening in the cylinder out of the way of a place where dirt and dust can accumulate, there is very little risk of pickup up any debris.

[Wren Hensgen]

Another solution is dual solenoids, each one with one capped port, and one side connected to the cylinder. This lets you push it back down, and then vent to atmosphere.

[FrankJ]

Legal servos don't have the torque needed to turn a pressure regulator.

[DavisDad]

Originally Posted by FrankJ

Legal servos don't have the torque needed to turn a pressure regulator.

Never say never. A geared down continuous rotation servo would probably do it. But but not sure if you'd have needed position control w/out adding POT.