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Vapor Space - Volume

Use the Vapor Space - Volume calculation to account for the volume of material that is in gas phase and located in the region above the material in liquid phase within a closed container. This calculation is a function of these parameters.

  • Material partial pressure
  • Material Temperature (Gas Phase)
  • Material Compressibility Factor (Z) and Molecular Weight

The amount of equivalent liquid in the vapor spaces is calculated by using the following equation.

Where:

V = Vapor space volume

Ve = Equivalent liquid volume at reference temperature

T = Absolute temperature

P = Partial pressure

MW = Molecular weight

R = Gas constant

z = Compressibility factor

p = Density at reference temperature

ClosedEXAMPLE: Vapor Space - Volume

A product in a tank has a density of 54.5 lb/ft3 a partial pressure calculated to be 8.4 psia, a compressibility factor of 0.989, and a molecular weight of 44.2. The tank temperature is 134 °F, the maximum capacity is 3540 ft3, the product volume is 1000 ft3, resulting in a vapor space volume of 2540 ft3. Question: What is the volume and mass of this product in the vapor space?

n = 3.39 lbmol

M = 149.69 lb

Ve = 2.75 ft3

See Configuring - Vapor Space Volume Calculation for details on how to configure this calculation.