Pneumatic plumbing configuration confusion

[marccenter]

Dear CD,
FRC3548 will be using pneumatics this year and the plumbing configuration that we are using agrees with what is found in the game manual so it should be a legal configuration. However, team 358, which has a great pneumatics web site which is extremely useful, shows a configuration that doesn't use brass fittings and as such weighs less. Furthermore, Andymark, shows another configuration for it's pneumatic system. Which one can we "officially use"?

I am raising this question because in an attempt to configure our system I now realize that other teams may be looking at any one of the three sources and arriving at the competition thinking they are good to go but may not be.

Since it is my first year using pnematics I don't have feel for how "closely" the inspectors follow the game manual configuration. Please weigh in on any thoughts and experience with pneumatics configurations at previous inspections? Thanks in advance

[Andrew Bates]

To answer your main question, The only legal configuration is the one that meets all of the requirements set out in the game manual.

Specifically the rules governing pneumatic are in section 4.1.10.

I feel you are asking about whether you can use plastic fittings or brass fittings. The answer is for the most part you can use either. Rule R86 requires that you couple the relief valve directly to the compressor. For this connection you would use brass fittings. The wording of the rule and it's enforcement last year indicates they don't want it connected via flexible tubing.

The only other place you would likely use brass fittings is to connect to the high pressure gauge, pressure switch, and dump valve. Teams with typically assemble these three items together into one assembly with brass fittings. However you could conceivably leave them separate and connect them together with tubes.

Good luck.

[Jaxom]

Originally Posted by marccenter

Since it is my first year using pnematics I don't have feel for how "closely" the inspectors follow the game manual configuration. Please weigh in on any thoughts and experience with pneumatics configurations at previous inspections? Thanks in advance

Hopefully, *very* closely; I know I do. Pneumatics have the capability to be quite dangerous; you want them properly controlled. The diagram in the rules is just an example; you don't have to follow it exactly. But you DO need to make sure that you have working & stored pressures correctly segmented & gauges visible, the relief valve on the compressor, and the pressure switch on the stored side.

Since you've not used pneumatics before, I'll make one request -- please make sure you put your manual vent plug in a very reachable & visible place (I really wish the rules would make a label mandatory...). Put it where you wouldn't mind your hand going if the robot is on fire & the pneumatics are randomly firing... That might seem like a too-obvious suggestion, but it's amazing where teams put them. In Breakaway I had to make a team move theirs; you had to reach through their kicker to get to it.

[ToddF]

Also, be sure you set the pressure on the relief valve so it relieves at the proper pressure. Out of the box, the valves can be randomly set. We didn't do this ahead of time last year, and when the inspector checked, it was set wrong.

That led to one of these conversations:
"Who was supposed to set the pressure?"
"Not us. I thought you were supposed to set it."
"We don't set it. I thought you guys set it."

[jspatz1]

Regarding your specific question about brass fittings: Only the fittings between the compressor and the auto-relief valve must be brass. All other fittings must only be shown to be rated for at least 125 psi.

[matthewdenny]

Okay, now I'm confused. How can we directly attach the pressure relief valve to the compressor? Our compressor (VIAIR from 2012) only has one connection which is a tube push in connector. Also where in the rules does it differentiate that you need a brass connector in certain places?

[Kevin Sevcik]

Originally Posted by matthewdenny

Okay, now I'm confused. How can we directly attach the pressure relief valve to the compressor? Our compressor (VIAIR from 2012) only has one connection which is a tube push in connector. Also where in the rules does it differentiate that you need a brass connector in certain places?

Originally Posted by R86

The relief valve must be attached directly to the compressor or attached by legal fittings connected to the compressor output port. If using an off-board compressor, an additional relief valve must be included in the high pressure side of the pneumatic circuit on the ROBOT.

I'd read that as the relief valve must be connected to a legal fitting that's directly connected to the compressor. So you attach a T fitting to the compressor output and then the relief valve to one side of the T and a tubing connector or whatever else to the other side.

The rules don't say that you have to use brass fittings, just that they have to be rated for 125 psi. If you can find plastic fittings rated for that, then that works too.