Real gas:

Wheeas the so-called permanent gases, namemy, those which are difficult to liquefy and have a relatively low critical temperature, obey the perfect gas law to a satisfactory approximation, this is not the case At high pressure and low temperature. We are dealing here with so-called real gases conforming To the following equation:

P . V = Z ( T , P ) . n. R . T Z = the compressibility factor

Table for Z de l ’Hélium 4 t (°C) P (bar) 1 5 10 20 30 50 100 150 200 15 1, 0005 1, 0024 1, 0049 1, 0098 1, 0147 1,0244 1, 0487 1, 0727 1, 0965 50 1, 0004 1, 0022 1, 0043 1, 0086 1, 0129 1, ? 1, 0429 1, 0641 1, 0851

Molecular weight:

Quantity of gas comprising N particles (Avogadro nunber N). The mass of these N particles is equal to the molecular weight M.

Avogrado (Avogrado number):

The number of atoms in 12,0000 grams of carbon isotope 12C, an arbitrary figure selected as a standard reference For atomic weights. N = (6, 022169+/- 0, 00040) . 10 puissance 23

Table for l ’hélium 4, Density (1 bar) Température (°C) vapeur (Kg.M puissance-3) 0 0, 176 15 0, 167 50 0, 149

Remark: Hélium is noncorrosive and may be employed with all meterials.

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