does anyone know the rules for wiring and plumbing the compressor to be used off the robot? we plan to precharge an accumulator on the robot and left the compressor off. has anyone done this before?
This is perfectly legal, just make sure to have a safe way to close the air system before you take the compressor off ;).
Also, make sure to always charge the system before each match.
Personally, I think you’re better off keeping it on the robot, but that’s really a complete matter of opinion, so don’t take my word as written law.
We have done this since we’ve had pneumatics on our robots (which is the past three years). We always want to get the pump on, but weight never allows. This year we came closer than ever, but it still didn’t happen.
Our design for a remote compressor is actually pretty cool. I’m not sure if I remember exactly how it works, but let me try. It has a battery, compressor, pressure guage, limit switch, and pressure switch. The battery is wired to the positive on the pump, and the negative goes to the limit switch, which then goes to the pressure switch, which then goes to the pump. Pneumatically, the air goes from the pump to a check valve to a T fitting. From there, one end goes to a simple valve used to purge the system before we un-hose the bot. The other end of the T goes to the pressure switch and guage, and to the robot. On the robot, we use another valve. We simply open the valve, air up, close it, and purge the system outside of the robot so it can be disconnected.
Sounds confusing, and I’m not exactly sure it’s correct. I’ll try to get a pitcure next time I can.
Last year we used a remote compressor.
The first valve on our robot was a shutoff valve with a quick connect at the open end.
From that point, we had the 120 psi gage, the reservoirs, the regulator, the 60 psi gage, and then our solenoids.
We made a smal case for a battery and compressor with an on / off switch.
Made a fitting that went from the compressor to a T fitting - vent valve on one side of the T and then a short piece of hose on the other.
We would hook up to the robot thru the short tube, pressureize to 120, close the valve on the robot, open the vent on the compressor and disconnect.
We were always asked at inspection how we limited to 120 psi. We just had 120 marked on the gage and made sure we stopped there.
It is a good way to work if yo uonly have limited needs for pneumatics. You can only use two reservoirs and the rules (Q & A) say you cannot coil a bunch of extra hose to make more storage area.
we have a sensor that stops pumping at 120PSI, but I am not sure if this is what this conversation is about, I am new 
The discussion is about leaving the compressor off the robot and just pressurizing the accumulators (little air tanks) prior to each match. This lets the team save weight, but the amount of air used is limited. No 2"x24" cylinders on that bot :).
We did this when we went overweight.
Basically, you need some way to cut off air on each side.
Exact implementation can vary (the simplest automatic being wire the pressure switch in series to the compressor, then hook that up to a fuse/switch, then battery)
I dont know any rules on the wiring of the pump, but I shall read the rest of the fourms to see 
Our team did this too the entire season. We carried around a battery/pump “thing” and hooked it up to a valve which was hooked up to the two reservoirs of air. It does have its limits (you WILL have to make some sacrifices), but it worked well for us.
But at IRI, we got this new, welded “bling-bling” frame, which was (by my calculations in week 5) 2 and a half pounds lighter than the t-nut/extrusion “ghetto” frame we used earlier in the year. Then we had the weight to put the pump back on.
Moral of the story: Use a pump in combination with a welded “bling bling” frame
Moral of the story #2: Don’t weld anodized aluminum “super bling bling” because it really doesn’t work. :yikes: