- Member since
February 2003
- From: Tacoma WA
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Posted by gjek
on Tuesday, April 11, 2006 3:14 PM
The liquid in a propel can is a gas that is a liquid under pressure. It is normally at room temp. When you use it, the gas in the can escapes down the airhose. the liquid gas in the can starts to turn back into gas as the pressure in the can drops. As this happens, due to one of those laws of physics, the temp inside the can lowers. The more you use the can the colder it gets. It will get to the point ice forms on the can. Now because the liquid and gas are much colder, the pressure drops until the liquid can warm back up. Some people float their can in warm water while painting. CO2 gas in a tank is normally at room temp. The pressure in the tank is high enough to force it into a liquid state just like the liquid propel. CO2 has the same things happening as propel. However, CO2 is usually purchased in much larger quantities than the propel in a propel can. Because of this larger mass, the change in pressure and temp is not noticed with normal airbrush use. CO2 also mantains about 800 lbs of pressure in the tank until all of the liquid CO2 is used up. More than enough to compensate pressure loss due to temp change. Greg
Msgt USMC Ret M48, M60A1, M1A1
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