Vapor pressure


The pressure (usually expressed in millimeters of mercury) characteristic at any given temperature of a vapor in equilibrium with its liquid or solid form. Sometimes called “vapor tension.”

Vapor pressure is about liquids boiling. If I asked you “at what temperature does water boil?” You could say 212° F. or 100° C., but that is only true at atmospheric pressure. Every product will boil (make bubbles) at some combination of pressure and temperature.

If you know the temperature of the product you are pumping or sealing, you need to know its vapor pressure to prevent boiling and the formation of bubbles in the pump or stufing box.

In the charts section of this CD you will find vapor pressure charts for several common liquids.

  • Vapor pressures -180°F to 60°F, GR013
  • Vapor pressures -60°F to 240°F, GR014