Are we allowed to use helium?
 

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?

Re: Are we allowed to use helium?
 

I can't imagine what for...?

Re: Are we allowed to use helium?
 

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?

Re: Are we allowed to use helium?
 

They will sound pretty funny shouting instructions to each other:D

Re: Are we allowed to use helium?
 

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.

Re: Are we allowed to use helium?
 

Balloons to block shots?

Re: Are we allowed to use helium?
 

...and people thought 1114's climb was fast. ;)

Re: Are we allowed to use helium?
 

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

Re: Are we allowed to use helium?
 

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.

Re: Are we allowed to use helium?
 

Best place to get an official answer is the Q&A. Any answer you get here means absolutely nothing.

Re: Are we allowed to use helium?
 

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.

Re: Are we allowed to use helium?
 

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 :)

Re: Are we allowed to use helium?
 

"We cannot comment on individual robotic designs"

Re: Are we allowed to use helium?
 

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:

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.

Re: Are we allowed to use helium?
 

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.

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.

Re: Are we allowed to use helium?
 

Helium is mined.

Re: Are we allowed to use helium?
 

That's the most correct answer so far (Plutonium also releases alpha particles). Then it gets trapped in the ground and can be mined. Nice!

Maybe one day we'll be able to harvest it from fusion reactors as well (or the sun).

Re: Are we allowed to use helium?
 

which brings us to...

do you REALLY need to use that helium??

SAVE THE HELIUM!!! ;)

Re: Are we allowed to use helium?
 

Re: Are we allowed to use helium?
 

...Now i'm wondering if I could put enough helium in a pneumatic tire to make it float. R78 doesn't say the pneumatic wheel has to be serving a 'wheel' purpose, and a floating pneumatic wheel would be just as effective as a balloon at getting in the way.

Re: Are we allowed to use helium?
 

Even if there isn't a rule about it, I don't see a point in it. If you're over on weight, start making swiss cheese.

Re: Are we allowed to use helium?
 

The short answer is "No".

It would take ~46 cubic feet of Helium at NTP to raise a 3 lbm wheel.

Re: Are we allowed to use helium?
 

Well, that would depend on what constitutes an "air filled (pneumatic) wheel". Do I require the hub? Does the inner tube alone count?

I realize I'm lawyering, but that's kind of the point of this discussion, no?

I would tend to agree with Tristan's view that using a balloon *may* not constitute a violation of the pneumatics rules, but its certainly a grey area.

For years, the pneumatics rules forbade pneumatic wheels without specifically calling out an exception, but teams USED pneumatic wheels. Nobody noticed that the way the rules were written forbade them, because nobody thought of a pneumatic tire as being a pneumatic device.

Re: Are we allowed to use helium?
 

Interestingly, adding helium to a fixed volume will make it LESS likely to float. In the case of a mylar bag, the maximum lift potential happens when the bag volume just reaches its maximum. If you keep pressurizing the bag, you are adding more gas mass, but keeping the volume fixed. Density increases, causing a loss of lift. If the bag were strong enough, it would be possible to pressurize the bag to the point where the mass of helium in the bag would be greater than the air it displaced, actually making the bag sink, rather than rise.

Re: Are we allowed to use helium?
 

Not true. Prior to specific rules, the flow chart for checking the legality of parts would allow pneumatic tires.

Re: Are we allowed to use helium?
 

Was there ever a year when the flow chart was considered to have the status of an actual rule, rather than being a (possibly incomplete) summary of the rules?

Re: Are we allowed to use helium?
 

The fundamental question concerns the meaning of "pneumatic" in the rules. If they mean to restrict all pressurized gases with it, then this is relatively clear-cut. If they mean to restrict air only, the existing rules on safety, energy storage and parts utilization could be applied to helium, without posing undue risk. An appropriate level of regulation can be achieved in at least two substantially different ways—so why presuppose that FIRST intends one and not the other? (I also eagerly await FIRST's response, if anyone chooses to ask the Q&A for it.)

Also, the 1 atm specification you mention—although reasonable—is not stated in the rules, and to my knowledge has never been articulated by FIRST. As a result, teams may wonder why other indications of FIRST's intent aren't really in harmony with that specification:

• Is the nitrogen in a gas shock above 1 atm? (Probably—so why does FIRST explicitly exempt it?)
• What if I had a small, sealed, air-filled container at 1 atm, inserted it into a vessel and used a legal vacuum pump to evacuate the vessel to 0.8 atm? Is the container now subject to the pneumatics rules? (In other words, is the 1 atm gauge or absolute?)
• Is a nitrogen-filled tire tube an "air-filled (pneumatic) wheel" for the purposes of the rule? (And is that because commercial nitrogen is "air", or because all compressed gases should be subject to the pneumatics rules?)

By the way, since I didn't really explain my rationale earlier: the energy source rule covers forms of energy that are "used" (I presume this means intentional energy release during a match). Every robot can catch fire: that doesn't mean we prohibit every single robot because it's a source of (chemical potential) energy not enumerated in the rules. By the same token, if popping a balloon is an unintended failure mode, there's an equally good case that that energy release is not use, and thus not subject to the energy storage rule. The safety rule covers it adequately.

With regard to the compressed air source rule, it uses the word "air", and so I have a hard time accepting that it covers gases that are not (in any conventional sense) air. As others have noted, calling commercial-grade helium air is as bad as calling it natural gas, uranium or starstuff.

The 1999 rules contained (and possibly introduced) many of the pneumatic system principles we use to this day. I'm certain that the use of pneumatic wheels in FRC predates the advent of the parts usage flowchart several years later (unless there was another flowchart prior to 1999).

I distinctly remember a team using the Skyway Ø8 in pneumatic wheelchair wheels in 2001, and many teams using them thereafter. (I suppose they could have been filled with something else, but I kind of doubt it.)

I think the flowchart was called out as enforceable by a numbered rule in some years, but in others it was merely appended to the manual and was ruled advisory (like a Q&A response).

Re: Are we allowed to use helium?
 

Alan,
Whenever a team used a part that was not covered by the rules, the inspectors used the flow chart to determine it's legality. Remember that materials were far more restricted in the past than they are today. Teams actually used packing material in the KOP because anything in the kit was legal.

Tristan, how can you make a distinction between air and other gases when the rules do not. The rules speak to "air pressure" which is by definition a mixture of gases. Gas shocks are specifically excluded, other devices that contain pressurized gas are not excluded and therefore not legal for use on the robot. As to robot rules, I have electronic copies back to 2001 and in that year materials you could use on the robot were limited...

The materials that you are allowed to use to build the robot are limited. There are three sources of
materials:
Sources of Robot Materials Location
1. Parts found in the Kit of Parts Appendix B, Inventory list
2. Parts from SMALL PARTS, INC. SMALL PARTS, INC. Catalog
Appendix D, Ordering information
3. Parts from Additional Hardware List Appendix C

Now I don't have a Small Parts Catalog from that time but I don't remember them selling pneumatic tires. Wheels provided in the kit (and listed in Appendix C) were specifically "5"-8" Ø, Up to 6 non-pneumatic".
As to the 1 atm, will someone please explain how a deflated mylar balloon would magically fill up if the pressure inside and outside the balloon are the same? Assuming that gravity and temperature are ignored, convince me that helium gas would magically move to the interior of the balloon and fill it with no other force acting on it. And if that is the case, why would the balloon deflate when it is opened? (Ignoring of course the lighter than air helium gas)

Re: Are we allowed to use helium?
 

I'll try

Pressure is the sum of the forces from all gas molecules hitting the container walls, divided by the walls' area. Thus, it is proportional to the number of collisions per unit area, and the velocity of the particles. The latter is temperature, which we're ignoring. The former is based on the container surface and the number of gas molecules. In elastic balloons, these two do not rise proportionally, because the internal pressure is balancing not just the external pressure, but also the the elastic potential energy of the balloon. In a mylar balloon (not overly inflated), the internal pressure is not compensating for elasticity, so the two pressures are in fact equal--the increasing volume exactly compensates for the increasing number of gas molecules. So it's not that there's no force acting on it, it's that the force in P=F/A is increasing exactly proportionally to A.


...Maybe.
<Is about to be killed by Ether>


EDIT: Hey, hey! It's seems that someone actually did this experiment. See page 3, it is indeed constant at 1atm. Who'da thunk? I was not expecting to get that right.

Re: Are we allowed to use helium?
 

Siri,
Thanks for trying. What I am trying to understand is this. You have a volume of gas at 1 atm. You have a deflated balloon, flat, no internal volume. The inside and the outside of the balloon are also at 1 atm. The volume of gas is connected to the balloon with a hose or tube. Explain how the volume of gas will somehow expand the balloon and fill it if all pressures are equal. This is what was proposed earlier in the thread. I see no force that will impel the balloon to inflate and for the gas to pass from one volume to the other.

But what if the rules *themselves* were written in helium?! I'm fairly certain this would enable some kind of time-space paradox that the GDC only simulated once during game season planning, and might require a firmware update on our bridges...

Re: Are we allowed to use helium?
 

Al,

A 1 mil thick sheet of Mylar weighs about 5*10^-5 pounds per square inch. So the pressure inside a partially-filled Mylar balloon would be about 0.00005 psi greater than atmosphere. Is that what you are arguing about here?

Re: Are we allowed to use helium?
 

Add molecules at constant pressure to a flexible but inelastic container. The volume increases. I don't see how this is an open question.

A typical mylar balloon has exactly ambient atmospheric pressure inside it. If you manage to defeat the fill port's built-in leakage and overfill it so that it's starting to swell, it actually becomes less buoyant. After a couple of hours, it will have leaked back to ambient pressure.

Re: Are we allowed to use helium?
 

I think the only mixture of gases the rules refer to is air, which isn't an arbitrary mixture, but one with a reasonably-well-defined range of compositions. I'm contending that there is an implicit distinction between air and all gases not mentioned.

I actually just looked back at the 1999 rules, and they suggest that the wheels came from Small Parts—which is not how I remember it either (and a slightly-newer Small Parts catalogue doesn't list them). Skyway provided wheels in some of those years via something like a PDV.

Also, in 1999 there was no language about "non-pneumatic" wheels—so I guess it did arise as an issue at some point.

Re: Are we allowed to use helium?
 

By changing temperature. Helium is pretty close to an ideal gas as far as approximations go, so it will follow the law PV/T = constant. Since the P is being held constant, when the volume increases, the temperature will decrease, assuming the process is conducted instantaneously with no heat transfer. Since the balloons conducts heat, and because the process takes time, you won't see as significant a temperature drop as the naive law predicts because heat will start transferring into the gas as soon as there is a temperature differential.

The force is generated from the difference in concentration of the gases. http://en.wikipedia.org/wiki/Diffusion.

Re: Are we allowed to use helium?
 

Al is correct about the 1 atm thing, but only in a painfully pedantic way. It does take a tiny (and I do mean tiny, neglecting any fill valve characteristics) pressure differential to cause gas to flow into an uninflated flat Mylar balloon... because the pressure inside the balloon must lift the "top surface" of the mylar as the balloon changes shape from flat to an oblate spheroid. In an earlier post I gave an estimate of the theoretical pressure differential required to do this.