My team wants to use helium during competition. We understand that we are not allowed to bring a helium tank to the site, but are we allowed to use helium during matches in competition?
I can’t imagine what for…?
Might be the classic “helium-filled frame” trick. Or they might be trying to affect the flight of frisbees.
If you can’t bring a helium tank to the site, how on earth are you going to use helium in matches?
They will sound pretty funny shouting instructions to each other:D
Tie a ton (not literally) of balloons to your robot before you get it weighed.
Last time I saw the ‘no lighter than air gasses’ rule was 2010 so I suppose it would be legal.
However, it wouldn’t help as the dictionary definition of weight “A body’s relative mass or the quantity of matter contained by it, giving rise to a downward force; the heaviness of a person or thing.” would not change no matter how much buoyant force you had lifting it. The apparent weight would; the actual weight wouldn’t.
Balloons to block shots?
…and people thought 1114’s climb was fast. 
I had this idea and was overruled by the kids on the team. We looked at the pneumatics rules and didn’t see a problem with it, other than psi. Party City has Hello Kitty balloons really cheap, I wanted a few to surprise the tall full court shooters…maybe another year lol
Well I don’t wish to specify our objectives with helium. So to my understanding we have the right to use helium in our robot.
Best place to get an official answer is the Q&A. Any answer you get here means absolutely nothing.
The robot’s true mass is not measured during inspection. The official method of weighing an FRC robot uses a force-sensing scale, so the property that matters is what you’re calling the “apparent weight”.
The answer to such a general question is likely to be something like this:There are no rules specifically prohibiting helium or other nontoxic gases. However, the robot must still obey all rules.
It might be able to ruled out under the “unsafe materials” rule, as it is an asphyxiant… but then again most things will suffocate you if you breathe in too much aside from air 
“We cannot comment on individual robotic designs”
It would be better for everyone if you just told us. I can almost guarantee you didn’t stumble on some huge game-changing secret that no one else figured out. There’s no need to keep secrets here, if you’re obscuring something that’s potentially illegal you’re only hurting yourself.
Regardless, there are several ways that helium would be illegal to have on a robot. Is helium doing work (in the physics sense)? Then it could be argued that helium is a violation of R37:
Non-electrical sources of energy used by the ROBOT, (i.e., stored at the start of a MATCH), shall come only from the following sources:
compressed air stored in the pneumatic system, a change in the altitude of the ROBOT center of gravity, and storage achieved by deformation of ROBOT parts.
It looks like part A is a potential loophole, except that all compressed air must come from an FRC legal compressor, which just uses air from the surrounding atmosphere and not from a particular source.
In addition, almost any component involving helium would be a pneumatic component by definition. There are many pneumatic rules, but all require the use of unmodified OTS components and none of the rules allow you to use helium to fill tanks instead of normal compressed air.
You could use helium as the working fluid in your FRC-legal pneumatics system by connecting a helium source to the air compressor’s inlet port. You would need to regulate your helium source to approximately 1 atm, which is important because the inlet side of the compressor is not rated for pressure. Of course, you could only do this when pre-charging your pneumatics in the pit-- you couldn’t do it on the field.
EDIT: Also, compressing helium is harder to do than compressing air. You’ll want to operate the compressor at a lower duty cycle to compensate.
How would you use it in a match without a tank of some sort.
They definitely cannot comment on designs that the team refuses to reveal as part of the question!
It occurs to me that the poster from Raptacon never actually said they wanted to use helium on the robot, just during competition. I wouldn’t have a problem if the team kept a stash of pre-filled helium balloons in the stands and used them to do a high-pitched “chipmunk cheer” or something like that.
Safety? He is an asphyxiant, and while the “breathe-helium-to-talk-like-a-chipmunk” trick is usually harmless, people HAVE been hurt doing it.
Storage at anything greater than one atmosphere at your event location would be considered pneumatic. You can only pressurize the pneumatics system with a single legal compressor. The Q&A would have to be specific as to use in order for a valid response. If you were to plan a balloon as a defense device, the current rules do not cover such a device. You must ask the Q&A.
Although valid under most circumstances, I don’t think that’s a rigourously true statement. After all, there exist exceptions for pneumatic tires (including presumably their tubes) and gas-filled shock absorbers. The rules aren’t clear if these are intended to be the only possible exceptions (among pressurized components), nor whether pneumatic constraints are intended to encompass anything containing any compressed gas.1
And as was pointed out above, an ordinary sealed helium balloon is not providing energy, so the energy source rule does not apply. And the compressed air source rule doesn’t apply because it’s not compressed air!
This is definitely a good candidate for the Q&A. If they disapprove of it, I’ll be curious to see the grounds for their decision.
1 I don’t think anyone wants to subject the batteries to the pneumatics rules, just because they can exceed one atmosphere due to hydrogen generation. (And it’s not exactly negligibly in excess of 1 atm, given that they’re engineered with overpressure vents.)