Re: Al's Annual Inspection Thread 2015
 

Bingo.

Re: Al's Annual Inspection Thread 2015
 

As I understand it, this is legal. You can also add a length of 12 AWG wire between the Victor and the 14 AWG wire.

Re: Al's Annual Inspection Thread 2015
 

So let me cover both issues here, starting with the wire.
CIM motors have a slightly higher temperature insulation and in practice would be wired to a long length of wire. (They were originally designed for trailer tongue positioners as I remember.) In our application, you can run #10 to them if you so desire. The short length of higher temp wire still keeps them safe for our purposes.
The output port of the compressor is supplied with a check valve to prevent system pressure from bleeding through the compressor. I haven't examined one in a while so I don't remember if that fitting is part of the check valve. I will try and check tonight before we mount the compressor (maybe).

Re: Al's Annual Inspection Thread 2015
 

Thanks!

Re: Al's Annual Inspection Thread 2015
 

I know one of their different compressors, the 250c IG variant utilizes a completely separate check valve that has to be installed to work.

Re: Al's Annual Inspection Thread 2015
 

Just be really happy First doesn't make you take apart the motor and solder 12 AWG wires to it. :eek: In the integral HP world, the feed wires are always bigger than the wires in the motor. The manufacturer can make an engineering judgment on how big the wires need to be based on more known factors than the general case of power distribution wiring.

Re: Al's Annual Inspection Thread 2015
 

Circuit breakers are circuit protection devices, that means they exist to protect the wire. What they protect the wire from is the insulation getting so hot it melts. There are many types of insulation with many different melting points and the rating for the wire and insulation is dependent on the conditions it is used in. That means there is no universal rating for say a 12ga wire. The CIM wires enter the motor where the temps will be much higher than ambient. Because of that they use high temp insulation which means that particular 14ga wire can safely carry a 40a load.

It is not practical for all inspectors to be trained to identify all types of insulation, know their temp ratings and to have to check the type of insulation on a robot by robot basis. So FIRST makes the assumption that a motor MFG knows what they are doing when they selected the attached wire and that the average team will be using wire with low temp insulation and set the rules accordingly.

Re: Al's Annual Inspection Thread 2015
 

Several other things that get missed when building our bots.
1) Please allow easy access to the 120 amp breaker. No one wants to see their bot burn because the ref couldn't find the breaker.
2) The same for the pneumatic vent. Don't hide it.
3) Sharp corners. I don't like to see blood, espaeiclly my own :ahh:
4) If you are using pneumatics, please have the guages where we can see them.

Re: Al's Annual Inspection Thread 2015
 

James,
I checked our ViAir last night and the check valve is mounted directly to the compressor. It has a nice arrow punched into the body. The additional fitting appears to the transition for supplied check valve. I did not pull ours apart to see what, or if, there is a threaded transition on the check valve. This is certainly a question for the Q&A I think. I like that there is some metal at that port to help cool off the output air. That little compressor does run hot if you run it often.

Re: Al's Annual Inspection Thread 2015
 

I see that your team has asked the GDC (Q360) if the check valve supplied with Viair model 250C-IG compressor is legal.

If that check valve is considered a part of the compressor, then NOT using it would violate R65. If it is considered a separate part, then using it would violate R66.

Based on the GDC's response to 2014 Q325, I think the hose AND the check valve that come from the manufacturer should be considered parts of the compressor, and therefore required per R65. Of course my opinion is worthless at inspection.

Eagerly awaiting the GDC's word on 2015 Q360. :)

Re: Al's Annual Inspection Thread 2015
 

Yup, that was me asking... I saw them answer a question that check valves are illegal (which was expected), but wanted to make sure there was another answer directly applicable to the compressor we're using so an overzealous inspector didn't point to that Q&A and make our whole system worthless. I can't overturn inspectors when dealing with my own team :)

Re: Al's Annual Inspection Thread 2015
 

All the First legal compressors have two check valves in them. One on the inlet, one on the outlet. Without them, the compressor essentially becomes a cylinder mounted to a motor.

Re: Al's Annual Inspection Thread 2015
 

Thanks Al, will submit a Q&A.

FWIW we have mounted numerous 'hard' brass fittings to the compressor outlet to aid in cooling off the compressed air.

Edit: Q&A here - https://frc-qa.usfirst.org/Question/...fitting-remain

Re: Al's Annual Inspection Thread 2015
 

Right, check valves are pretty necessary for a compressor, but most of them have it "built in". The 250C IG has it attached to the required leader hose, and it's real easy for it to be viewed by an inspector as a separate part.

Re: Al's Annual Inspection Thread 2015
 

I understand. :)

From a functionality point of view he check valve needs to be attached directly to the compressor to keep the compression ratio as high as possible. The braided hose there to keep people from attaching plastic hose directly to the compressor which can be hot enough to cause the plastic hose to fail.