Questions
 

Hey CD world,

we are a second year FRC team but have not used pneumatics for actual competition. So of course we have a couple questions.


The rules state that the safety pressure release must be directly connected to the compressor. So does this mean it must be physically touching the threads coming out of the compressor or can we have a couple T's between it and the compressor.

Can we turn the top of the compressor so that the B port is where the A port is normally?

Our current setup has two separate storage areas,so we have two storage pressure regulators. Are we allowed to do this?

Thanks,
Austin
2783=2010

Re: Questions
 

The FIRST pneumatics manual should have answers to most, if not all, your questions.

--Ryan

Re: Questions
 

and the Q&A should have the rest of the answers, if you ask the right questions.

http://forums.usfirst.org/forumdisplay.php?f=23


My somewhat educated guess is that you need to screw the pressure relief valve directly into the compressor, and you need to leave the screws that hold it together, alone.

Re: Questions
 

Also there is a lot of helpful information on here

http://www.team358.org/files/pneumatic/

Thank you 358!

Re: Questions
 

Part one of your answer lies here...
<R77> The relief valve must be attached directly to the compressor. Teams are not allowed to adjust the 125-psi relief valve.

If you are asking as to which port the relief valve is located, the answer is either side that is convenient they are both output ports.
If you are asking, can you have two of your storage tanks be on the low pressure side, then the answer lies here in <R76>...
B. Only the compressor, relief valve, pressure switch, pressure vent plug valve, pressure gauge, storage tanks, tubing, and connecting fittings may be in the high-pressure pneumatic circuit upstream from the regulator.

This gives you max storage anyway. You may have an additional regulator(s) on the low pressure side following the main 60 psi regulator.

Re: Questions
 

Aren't the two ports different size pipe thread? Might make it hard to put it on the most convenient side without taking the top off the compressor and turning it around, which might violate the "pneumatics parts are sacred" rule?

Re: Questions
 

According to the diagram here (Pg 5), one port is 1/8-27 NPT, the other is 1/4-18 NPT

Re: Questions
 

Yes, they are, but the answer merely responded to the question.

Re: Questions
 

I think I need to better explain my questions.

On the safety pressure release, we are trying to fit the system in a very small spot. So we are trying to fit all the FIRST required sensors and such to be on the side of the compressor with the motor. Because of this it is requiring us to have the pressure release between a set of T's and the compressor. (is this allowed?)

Flipping the top of the compressor was just to make it easer so we wouldnt have to go through another down-sizer

On the pressure regulater, we are having the air flow immediately split into two systems once it exits the compressor. So essentially we have a system for the right side of the robot and a system for the left. So can we have two main regulators?

We have checked the pnuematics manual but it says on the first page that it is just for suggestions and are not official rules.

Thanks Again,
Austin
2783=2010

Re: Questions
 

can you just screw the pressure relief valve into the motor side, then attach a 90 degree quick connect hose fitting into the other side, and run a plastic tube to the rest of the stuff?

Re: Questions
 

Careful; although rotating the top of the compressor looks pretty straightforward (and it is), when the question of whether or not we were allowed to do it was posted to the Q&A a few years ago (expecting a "yes" answer"), the answer was a solid "NO".

See this post

Re: Questions
 

Thanks Gary!
One down two to go.

Re: Questions
 

That's the ruling I had in mind....thanks Gary for finding it

Ask Q&A about the safety valve needing to be directly on the compressor.

It should function just fine if it's on a T that is connected directly to the compressor, but there may be some reason the GDC does not want you to do that?

Re: Questions
 

It is possible if a fitting is placed between the compressor and the relief valve, that it could affect the discharge rate of the relief valve. The inspectors would have no way of determining this with a visual, external inspection.:)

Re: Questions
 

On the question of disassembling the compressor head and reorienting the answer would be no. You may not modify any of the pneumatic parts. See R73 for a complete list of items not allowed in the pneumatic system.

On the question of splitting the high pressure side to feed two sides of the robot, this part of rule R72 would seem to indicate it is allowed.

G. Pressure regulators with a maximum bypass pressure of no more than 60psi.

However to satisfy the other parts of the pneumatic rules, the second regulator would also need a gauge to indicate 60 psi.
As to the question of adding a "T" fitting to allow the relief valve to be mounted at the compressor, there does not appear to be any rule that would prevent it. The intent of the pressure relief valve is to protect the system in the case of a failure in the pressure switch and a blockage in the output of the compressor. I believe that a "T" would fulfill this safety feature. However, a team must ask this question on the Q&A.

Re: Questions
 

The 125 psi blow off valve has to be directly on the compressor.

The digital shutoff switch can be anywhere on the high pressure side of the system.

Re: Questions
 

Sent the questions on to the GDC Q&A so we will see.

Now another question came up. How many modules can you have to power soleniods? In Labview it has two choices of modules, so I would assume that we could have too NI modules with solenoid breakouts on each. I can't find the specific number in the rules myself. Any ideas?

Re: Questions
 

We can have two solenoid modules in slots 7 & 8.
And there are always Relays/Spikes too.

Re: Questions
 

Alright, thanks!

Re: Questions
 

one more question......can two solenoid valves be wired into one output?

Re: Questions
 

How many solenoids can fit on the head of a Solenoid Breakout pin...?

I know Eric has said that the 24v power supply cannot handle much more than 8 coils, so doubling those up is not a good idea, legal or not.
Haven't heard about Breakouts running at 12v at all, but I imagine there wouldn't be a problem running multiple solenoids off a single set of pins..

You can have as many as you want attached to a Spike.

I haven't seen a rule or Q&A ruling that addresses this. Another good question to ask Q&A (and Eric).

Re: Questions
 

Looks like you got an answer

No fittings allowed between the pressure relief valve and the compressor. And since the two ports are different size, I guess that only leave one location for the prv and one to take off the flow.