General Information about Cryo-Fluids

  4He 3He N2 H2 O2
Molar mass g/mol 4.003 3 28.013 2.016 16
Boiling temperature K 4.21 3.19 77.4 20.3 90.2
Density (fluid) g/l 125.0 ? 808.6 70.8 ?
Density (gas) g/l 16.89 ? 4.59 13.38 ?
Latent heat J/g 20.6 ? 198.6 445.5 ?
Latent heat kJ/l 2.56 0.48 160.6 31.5 245
Critical temperature K 5.20 3.32 126.0 33.0 154.3
Critical pressure bar 2.28 1.16 33.9 13.0 50.4
Triple temperature K - - 63.15 13.8 54.36
Triple pressure mbar - - 125.3 70.4 15

 

The picture below shows the vapor pressure of 4He. According to the International Temperature Scale of 1990 (ITS-90) the temperature between 1.25 K and 5.0 K is defined by this vapor pressure, and the pressure curve for this temperature range is described by an analytical expression (the formula is part of ITS-90).

Vapor Pressure Curve of 4He (c)
Vapor Pressure Curve of 4He
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