Re: Are we allowed to use helium?
 

How would you use it in a match without a tank of some sort.

Re: Are we allowed to use helium?
 

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.

Re: Are we allowed to use helium?
 

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.

Re: Are we allowed to use helium?
 

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.

Re: Are we allowed to use helium?
 

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.)

Re: Are we allowed to use helium?
 

Tristan,
Come on, of course this fits in the pneumatics rules. If you want to get picky, they are not going to be using pure, laboratory helium, so it is going to be helium rich air above 1 atmosphere. If they would like to fill their pneumatic tires with the helium they are specifically excluded as you pointed out. Other storage is not.

Re: Are we allowed to use helium?
 

I agree that the most likely proposed use of the helium would be for "balloons" used to block a tall shooter, so let's look at that application...

If the balloons in question were made from elastomeric material, your typical balloon animal balloons, to be inflated the interior pressure must be above 1 atm. If the interior pressure is above 1 atm, they are pneumatics devices. I can see these as being illegal for two reasons. 1) They are not in the list of permissible pneumatics devices in R78. 2) Even if it were argued that a balloon is a tank of variable volume, unless it is a very special balloon, it would not be rated to 125 psi and would violate R76.

However, if the "balloon"s were made of mylar or some other inelastic material, it is easily possible to "inflate" the envelope of the bag with a volume of helium without the interior pressure exceeding 1 atm. If the bag started out flat (internal volume ~0), as gas is added, the interior pressure remains at 1 atm until the internal volume reaches the maximum allowed by the geometry of the bag. At that point, the volume can no longer increase, and adding additional gas requires a rise in pressure (assuming no temperature change). If the bag is made of light enough material, it could "float" before the interior pressure reached 1 atm.

So, it is conceivable that a team could attach to their robot a helium filled mylar envelope with an internal pressure not exceeding 1 atm. As the internal pressure does not exceed 1 atm, it is not a pneumatic device. Since the gas is not stretching an elastomer skin, there is no energy storage. There wouldn't even be a requirement to fill the bag using the robot compressor. You would, however, need to have a very good pressure gauge on your fill station so you could prove that the internal pressure doesn't exceed 1 atm.

Of course, such a bag might not hold up to getting a frisbee shot into it, but that's another problem...

Re: Are we allowed to use helium?
 

Is the intent of the pneumatics section to restrict any pressurized gas, to restrict air specifically, to restrict any gas used as a working fluid or to restrict air as a working fluid? To what extent are they intended as a game-balancing constraint, and to what extent a safety constraint? Is gas storage the only requirement, or is there also a requirement to be able to do work with the stored gas? And what if that work can only be done in a failure mode? What do the three stated exceptions (gas shocks, tires and vacuum) imply about the intent of the constraints? I don't think it's as clear-cut as you propose—but your interpretation is clearly plausible.

To the extent that safety is affected, R08 is a sufficient basis to rule case by case. There's no need to apply the pneumatic rules to every possible case if an unsafe condition exists—that's already grounds to prohibit it. And if it's a game-balancing constraint, there's an opportunity for the GDC to rule on it via the Q&A. That way they can make clear where the balance lies.

It's one thing to need to make a final ruling at an event based on the specific robot presented at inspection, and another to make the decision in advance. Let's at least give the GDC an opportunity to weigh in first—if they're asked and don't provide a straightforward response, then inspectors should definitely adopt a common standard, such as the one you described.

Is it reasonable to call any gas mixture "air", as long as it's not arbitrarily pure? (And what's stopping the team from using a quantity of lab-grade gas? Diffusion?)

Re: Are we allowed to use helium?
 

For students: Where does Helium come from? (No fair Googling).

Re: Are we allowed to use helium?
 

If I remember correctly, it comes from the radioactive decay of Uranium.

Re: Are we allowed to use helium?
 

Tristan,
You know all the answers to your questions. There are specific exclusions to air storage as you have pointed out. Everything else is subject to the rules. You know that.

Blue Box R78-The following devices are not considered pneumatic devices and are not subject to pneumatic rules (though they must satisfy all other rules):

A. a device that creates a vacuum

B. closed-loop COTS pneumatic (gas) shocks

C. air-filled (pneumatic) wheels

So if a team chooses to fill their tires with helium they are excluded. See also sec 4.1, R37, R76, R80 and other sections that may apply. If the GDC wishes to further expand it's exclusions based on a team question that may take place in the future, that is entirely possible. At this time there is no question about helium on the Q&A.
Todd, I submit that the filled balloon (from a flat, no volume state) is not at 1 atmosphere. If it were it would not change dimension. There would be no force pushing out on the envelope.

Re: Are we allowed to use helium?
 

Todd is correct about the pressure inside a mylar balloon being 1 atmosphere, subject to the stipulation he made:

"the interior pressure remains at 1 atm until the internal volume reaches the maximum allowed by the geometry of the bag"

Re: Are we allowed to use helium?
 

Where I work, helium comes from New Jersey.

Re: Are we allowed to use helium?
 

Midgets, as I recall.

Or maybe they filter it out of free air, using a very, very fine screen....then burn off the Hydrogen.

Re: Are we allowed to use helium?
 

No need to burn off the Hydrogen if the filter is fine enough. Helium atoms are smaller than Hydrogen molecules.