Is our air compressor getting too hot at 181.8 F?

I understand that these air compressors get hot, there is a “WARNING HOT” sticker on the belly of it. I’m concerned that there is something wrong with the compressor or some other component in the pnuematics circuit that could cause it to get that hot. Is it in fact, too hot?

This reading was taken on the top fin/heatsink deal on the top of the compressor.

How long was it running for?

I have this same infrared thermometer and have found it wildly inaccurate. The infrared emissivity of materials changes vastly depending on a lot of factors. I’ve taken readings of things that are known to be at the same exact temperature (having been in the same room for days to equalize) and have gotten widely different temperature values, for example, chair legs vs. chair seat vs. chair back. This happens even on high-end thermal imaging machines, but they usually have a way to account for it with settings for different materials.

Found this out the hard way when trying to determine the failure mode for a gearbox a few months ago. Some quick measurements with the same device you have led us to the determination that we were above the manufacturers temperature spec, but that was not the case.

I suggest using a thermocouple commonly found on multimeters instead to get a more accurate temperature reading.


Qualitatively, I’d guess it’s too hot (if that temperature’s accurate, regarding Cyberphil’s comments). If there was any less metal between the head and your tubing, you’d probably see the plastic start to soften up. It goes without saying that this is dangerous. Viair doesn’t give a max head/heatsink/case temperature, the closest thing is is the max ambient temperature (158* F). The 90C is only rated for 9% duty cycle (over an hour period) at 72* F, so I’d say it’s definitely not happy running at the temperature you’re measuring.

One thing many teams do with these small, low-duty cycle compressors is to stick a 40mm fan over the head, to keep excessive heat down. For testing at the shop, if you’re needing to keep air up constantly, consider an off-board compressor (with the same safety measures as usual - cutoff switch, blowoff valve, pressure relief valve), similar to what teams have done in previous years (not at competition though - it’s illegal this year!) to keep load off the onboard compressor.

I can agree to @Cyberphil. We were using the same thermometer to check the temp of our piece that was running on lathe and gave us ~80 to 90F. But when we touched it, it was for sure way over 100F.

The 90C gets toasty and more importantly inefficient when you start pushing it past that 9% duty cycle (“ON” one minute, “OFF” ten minutes)

We’ve often strapped a 40mm 12v computer fan (same as the Victor 88X speed controllers) onto our compressor head with small zipties. The forced air cooling helps.

The fan gets hooked up to a PDP slot with a 20A breaker and the rest of our CUSTOM CIRCUIT equipment. It’s on while the robot is on.

The tubing was getting noticeably soft, and the tanks don’t want to refill with air after the first actuation of the pnuematic cylinder that we’ve got plumbed in. (I hope I’m making enough sense here.)

In other words, the compressor takes about a minute to kick off and then we push a button and the rod of the cylinder shoots out and the compressor kicks back on and doesn’t shut off while it heats up to an inferno.

How many tanks? What do you have your Working Pressure regulator set to? How big is your cylinder?

Sounds like a leak downstream of your solenoid. If you reset the solenoid to closed, does the system return to pressure?

It is hot enough to soften the pneumatic tubing. I looked up what you suggested about using a multimeter’s thermocouple but mine doesn’t have one.

You’re correct that’s not safe

Thanks for the reply.

One tank.

I honestly do not know how to even check what the working pressure regulator is set to, much less reset it. Do you have a link to some instructions that are specific to FRC? I promise to god I’ve got the FRC Pnuematics Manual in my hands and I’m trying to see if I’ve missed it anything it says about that.

I wasn’t commenting on whether the compressor was too hot or not, just that the device you were using was not a good way to check the temperature.

If the tubing is getting soft I’d say that is a good indicator the thing is getting too hot.

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I don’t understand why you’ve got ‘custom circuit’ in all caps? I know you’re not yelling that at me, haha but I’m trying to understand.

You should have a gauge before the pressure regulator which shows your stored pressure (max 120psi), and a gauge after the pressure regulator which shows your working pressure (max 60psi). Make sure you have your pressure regulator going the right way.

I pulled up the FIRST Pneumatics Manual, and it only lists a single Regulator in the system.


This regulator & gauge should be set at 60psi


There is an arrow molded into the body of the regulator that needs to point from the high to the low side. If you have the KOP regulator it’s either on the bottom or at the outlet port

The Rulebook uses all caps to signify terms with specific definitions, and a “CUSTOM CIRCUIT” is a specific subsection of the electrical system - basically refers to sensors, coprocessors, cameras that are powered from a PDP slot and not distributed by FIRST.

Assuming that’s a standard plastic Clippard, about 2" round and 14" long? Not much air reserve.
How large of a cylinder do you have attached to it?

A big leak will show up as a hissing noise, a small leak might be significantly harder to find - I like using the hairs on the back of my arm to try to detect where the air is flowing. You can test for this by closing/resetting your solenoid and waiting to see if the system returns to pressure.


Yes, but how to check which PSI it’s set to?

By the gauge that should be installed directly on the regulator, as pictured in the manual.

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As shown in the drawing you should have two gauges in the system . The regulator should have one gauge plus you need another gauge upstream of the regulator (this is measuring your stored pressure and can be no more than 120 PSI. You adjust the pressure switch to get this value (can be lower if you want). You adjust the pressure relief valve to vent at just over this. You then adjust the regulator to control your working pressure (60 psi max).

With no air leaks and one Clippard tank it should come up to pressure quickly. Once it hits whatever you have set it to (120 max) the compressor should turn off and not restart. The system should stay at whatever you have set it to. If this is not happening you have a leak. It should have no issues holding pressure for hours.

I try to get behind the mule on questions I post to CD, because if I know if I just say “very hot” I’m gonna get 16 imperious replies dripping with pedantry and condescension; it’s demoralizing. So I thought that by showing what a thermometer reads would be good enough data.

Turns out “very hot, so hot that it softens the tubing” would have been sufficient! Thanks for your input, I really want to try reading temperature with a multimeter.