Quick Exhaust Valves - Illegal !?!?
 

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.... :(

Re: Quick Exhaust Valves - Illegal !?!?
 

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.

Re: Quick Exhaust Valves - Illegal !?!?
 

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.

Re: Quick Exhaust Valves - Illegal !?!?
 

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

Re: Quick Exhaust Valves - Illegal !?!?
 

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

Re: Quick Exhaust Valves - Illegal !?!?
 

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.

Re: Quick Exhaust Valves - Illegal !?!?
 

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

Re: Quick Exhaust Valves - Illegal !?!?
 

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

Re: Quick Exhaust Valves - Illegal !?!?
 

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?

Re: Quick Exhaust Valves - Illegal !?!?
 

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.

Re: Quick Exhaust Valves - Illegal !?!?
 

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?

Re: Quick Exhaust Valves - Illegal !?!?
 

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.

Re: Quick Exhaust Valves - Illegal !?!?
 

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.

Re: Quick Exhaust Valves - Illegal !?!?
 

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

Re: Quick Exhaust Valves - Illegal !?!?
 

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.

Re: Quick Exhaust Valves - Illegal !?!?
 

We have done it for years this way also with no issues. I read through the pneumatic rules and did not see anything pertaining to this.

Re: Quick Exhaust Valves - Illegal !?!?
 

There is no rule which states that the open ports of a cylinder must be attached to the solenoid, which means that there is no reason venting directly to the atmosphere is illegal.

If it were made illegal via a new rule, I'd be pretty upset. We are working on a design that uses pneumatics and hasn't been seen in FIRST (or at least in the many designs I've seen or studied from 2008, 2010, or 2014). It's pretty simple, but relies on the pressure venting directly to the atmosphere. We could possibly overcome a ruling, but only by moving to more expensive solenoid valves.

Re: Quick Exhaust Valves - Illegal !?!?
 

my thoughts exactly

Re: Quick Exhaust Valves - Illegal !?!?
 

Which is why I can't understand why quick exhaust valves are illegal. Perhaps it is the difference in venting near-atmospheric pressure to atmosphere, as opposed to venting 60 PSI to atmosphere? Still, I don't see the danger in it.

Re: Quick Exhaust Valves - Illegal !?!?
 

I view the new solenoid valve rule as a positive step. My impression is the GDC is keeping the pneumatics restricted to keep the robots safe & to simplify the inspection process.

This was done in 2010. No comment on if it would be legal in 2014

Re: Quick Exhaust Valves - Illegal !?!?
 

my thoughts exactly

Re: Quick Exhaust Valves - Illegal !?!?
 

There is no rule against this, and unless they create a rule outlawing single acting cylinders (which is what this would be) there won't be. I cannot imagine the GDC suddenly outlawing more than 50% of the available cylinder on the market.

Re: Quick Exhaust Valves - Illegal !?!?
 

I wouldn't assume that. The GDC outlawed almost all of the available wheels on the market in 2009. (Not that I expect them to do that again...)

Re: Quick Exhaust Valves - Illegal !?!?
 

Yes, as part of the game, and at the beginning of the season.

Re: Quick Exhaust Valves - Illegal !?!?
 

Forgive a ridiculous question, please --

What type of device, generally, is that which is described as a "pressure vent plug" in Figure 4-15 in the manual? (http://frc-manual.usfirst.org/viewItem/181#4.10)

This is what we all use to vent the system of pressure and does not appear to be among those items listed in R77-F.

What am I missing?

Derp -- I'm missing part B.

So, then, the question becomes -- what makes this valve functionally different from a ball valve / quick release valve?

Re: Quick Exhaust Valves - Illegal !?!?
 

Functionally, it is just like a ball valve. Except the rules call it a vent valve with the functional intent to dump all air out of the system. At least that is how I read the rules & Q&A comments.

The real question becomes how do you isolate the systems you use an off board compressor since you are apparently not allowed to use valves?

I really don't envy the GDC in all this. :]

Re: Quick Exhaust Valves - Illegal !?!?
 

I'm easily confused and think we're mixing names of devices. Here're some references:

Pneumatic Valve Types

A GUIDE TO UNDERSTANDING PNEUMATIC
DIRECTIONAL CONTROL VALVES

Wikipedia: List of valves

McMaster Carr

Re: Quick Exhaust Valves - Illegal !?!?
 

For the questions above here's a good video explanation
http://www.youtube.com/watch?v=X5SVF7TV8w4


As for my two cents, I agree. I think the GD is unnecessarily limiting with pneumatics. I don't agree that they want to "keep the bots simple" or make it easy for inspection. IF that's the case then I think its wrong and goes against the good portion of what FIRST is about.

This is one area I think FIRST could improve. Remove some of the restrictions that limit legitimate design ideas. Safety can still be maintained. Its done everyday it can be done in a first event.

Re: Quick Exhaust Valves - Illegal !?!?
 

Looks like we have a reply:

So this means venting to the atmosphere is legal. Now we know our shooter is legal! :yikes:

Re: Quick Exhaust Valves - Illegal !?!?
 

3175student17- thanks for the information; much appreciated!

Re: Quick Exhaust Valves - Illegal !?!?
 

Yet venting through a valve to atmosphere apparently is still illegal. Oh well, we've moved on from the original design, and invested two days and about $1000 in something else now.

Re: Quick Exhaust Valves - Illegal !?!?
 

With that in mind, to power a mechanism, a spring loaded cylinder can be fired by "releasing to atmospheric pressure" and the spring returning the cylinder to its starting position.