[ctt956]

Originally Posted by Bob Steele

In normal canned air there is no flammable liquid. The cooling effect is simply from the rapid decompression of the highly pressurized air.
The "fumes" are just air.... when you see frost on the item that is being cooled it is a result of the cold object's reaction with the humid room air. You might also see condensed water from the air in a humid environment.

Sometimes manufacturers add something called a bitterant to the air to deter individuals from inhalant abuse. The can will tell you if it contains this material but it is not hazardous and is definitely not flammable. A common bitterant is denatonium... the name is a reference to the denaturing quality of the substance... denaturing is adding something so it cannot be consumed by humans. You can avoid this in canned air if you purchase canned air without a bitterant.

I am concerned that you are spraying something other than "canned air" which is normally used as a duster. Many things are in spray cans.... and you would not want to spray WD40 or some other petroleum based material for this use but canned air would be fine.

You want the rapid decompression to happen as it hits the motor, this super cooled air will cool the motor. Normal compressed air can work... but the cans are usually a much higher pressure and will cool more and you cannot have a compressor in your pit anyway other than the one on your robot or the one you use in conjunction with your robot to fill your pneumatic tanks.

https://en.m.wikipedia.org/wiki/Gas_duster

Note that it says they're filled with fluorocarbons. Quote from the "Safety" section of the article:

Though not extremely flammable in gaseous form, many dusters use a fluorocarbon that can burn under some conditions. As such, there is also a warning label present on some gas dusters. When inverted to spray liquid, the boiling fluorocarbon aerosol is easily ignitable, producing a very large blast of flame and extremely toxic byproducts such as hydrogen fluoride and carbonyl fluoride as a combustion product.

And what caused this if it's not flammable? Yes, a commenter said it was the CPU, but that computer was unplugged.