Jon Myers

The water vapor in the air can condense if the pressure drops quickly enough which causes the air temperature to drop. This is what happens when you see contrails develop over wings when an airplane takes off or lands and the proper humidity and temperatures are present in the air. You can feel this same thing happen when you let the air out of a tire or use a CO2 cartridge to inflate a tire. In both cases you are going from a high pressure to a low pressure which lowers the air temperature. -Jon

John Schmidt

If the pressure (vacuum) is less than the vapor pressure of the liquid,
then the liquid will no longer be liquid but a gas...

On Fri, Aug 25, 2017 at 11:18 AM via OBRA wrote:

> Will air vaporize in a partial vacuum?
> Scenario: Pulsing vacuum from motorcycle cylinder head actuates
> mechanical fuel pump by creating a pulsing vacuum through a hose acting
> on a diaphragm. There is no leak past the diaphragm of any gasoline,
> air, or anything else yet "puffs" of some kind of vapor is plainly
> visible through the clear vacuum line. Is that air vaporizing when
> ambient pressure is momentarily reduced?
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d..@bicyclerepairman.us

Will air vaporize in a partial vacuum?
Scenario: Pulsing vacuum from motorcycle cylinder head actuates
mechanical fuel pump by creating a pulsing vacuum through a hose acting
on a diaphragm. There is no leak past the diaphragm of any gasoline,
air, or anything else yet "puffs" of some kind of vapor is plainly
visible through the clear vacuum line. Is that air vaporizing when
ambient pressure is momentarily reduced?