1 Scope
This International Standard defines the following quantities commonly used to express
the composition of gas mixtures:
-
—
mole fraction,
-
—
mass fraction,
-
—
volume fraction,
and
-
—
mole concentration,
-
—
mass concentration,
-
—
volume concentration.
For these quantities of composition, this International Standard provides methods
for
Conversion between different quantities means calculating the numerical value of an
analyte content in terms of one of the quantities listed above from the numerical
value of the same analyte content, at the same pressure and temperature of the gas
mixture, given in terms of another of these quantities. Conversion between different
state conditions means calculating the numerical value of an analyte content, in terms
of one of the quantities listed above, under one set of state conditions from the
numerical value of the same quantity under another set of state conditions, i.e. pressure
and temperature, of the gas mixture. Gas mixture composition can be converted simultaneously
between different quantities of composition and different state conditions by combination
of the two types of conversion.
This International Standard is applicable only to homogeneous and stable gas mixtures.
Therefore any state conditions (pressure and temperature) considered need to be well
outside the condensation region of the gas mixture and that of each of the specified
analytes (see Annex A).