Pneumatic pressure

We just got our pneumatic kits in… and have messed with them a little. Cylinder is surprisingly strong.

A topic came up concerning reservoir pressure… charging it with COLD air and letting the warming up increase the pressure a little. This particular topic, and gauges also, have been talk about a lot here. FYI, illegal.

What has NOT been mentioned is the inverse of it.

All the pneumatic teams I’ve seen are charging at the field using a battery powered compressor. So… they are filling with HOT air into a room temp reservoir. It’s cooling and losing pressure before/during the match as well as condensing a small amount of water into the system.

I’ve run the calculations… and it’s not a lot of loss, but I wanted to mention this to make teams realize this…

Edit: When calculating the loss of USABLE power… be sure to take into account that the system is useless well before pressures reach zero. So your baseline for calculations is not 0-100, but more like 30-100.

About how much psi was lost and what temperature was the air from the electric compressors? As a foot pump user, this shouldn’t be as much of a problem, but I am curious how much more effective a foot pump is.

As a foot pump user, it’s still a problem. Air, unless given time to cool or something to transfer the heat to, will heat up due to compression itself.

A foot pump has more mass to help cool the air during compression & transfer but the problem’s still there to a degree.

This is one of those problems that you can mostly ignore, but I think it’s important to understand the physics/thermodynamics behind the process.

If you’re getting 120F air out, when cooled to 75F, pressure drops to 92PSI. With a usable floor of maybe 30 PSI… this means you lost a measurable amount… not necessarily a needed amount.

At states and I presume worlds is that you have to use their air compressors at the queuing table. Not sure how I can charge it with cold air if I have to use their compressor.

Depends on if the compressor has a TANK. Bots use very little air. A typical 10-20 gal tank-equipped compressor would have no problem delivering 100PSI fills at ambient temps.

At our state champs… each team had ryobi/dewalt/milwaukee battery TANKLESS compressors at the field.

At our states (CA south LA) we had to use the EPs ryobi tankless compressors at the queuing table. We wean’t allowed to use our own or anything. So that point is moot anyways for being past states. Taking a look into the future how will worlds work? For normal tournaments ig I can bring a compressor that has a tank if they don’t care that much.

I guess the rules apply both ways. If they won’t allow COLD air… then they shouldn’t force you to use HOT air which will lose pressure.

Of course… everything’s at the discretion of the EP.

We should do some temp testing of 1)air stream coming from compressor 2)tank initial temp 3)tank temp 5 min after being filled.


I would remind teams that spot checks of pneumatic pressure is permitted at the discretion of the Head Referee.

I would ask EP how they will check pressure.

Interesting point but I assume these affects are negligible as I don’t think the air coming out of TANKLESS compressors is 50 degrees hotter than room temperature. If anything I assume it would be a few degrees at most and therefore negligible.


On one hand, I tend to agree… or especially considering that the net effect (# of actuations) is likely unaffected unless the team is really needing every single cylinder movement they can get.

On the other hand… it’s interesting to discuss it, and we don’t know for sure without some data.

I know that typical exit temps for 100 psi compressed air are well over 100F. Now, that temp ramps up from ambient as the pressure in the reservoir increases so it’s not like scorching air comes out immediately.

Easiest way seems to be getting the before/after temp of the reservoir.

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You’re aware this is really about lower than intended pressures, not higher.