4.11The refrigerant R407C is a blended refrigerant,
being a mixture of R32, R125 and R134A, and is
known as a ZEOTROPE fluid, and at a given
pressure each component part of the blend will
boil at a different temperature.
4.12 The pure refrigerant fluids R32 and R125 boiling
points are -52oC and -51oC respectively, and are
more volatile than R134a - boiling point -27oC.
4.13 Consequently R32 and R125 exert a higher vapour
pressure than R134a and should there be any
leaks in the system, the partial loss of one
component would result in the total remaining
blend being of the incorrect composition.
4.14 The magnitude of the leak is significant, but the
amount of the leak usually impossible to establish.
Small changes in the refrigerant quality / composition
may not noticeably affect the equipment
performance in the short term. However, the
leakage effect is irreversible and at some point,
the refrigerant has to be reclaimed and returned
to the manufacturers for reblending or disposal,
and the system would require evacuating and
6.6 Individual HFC's have differing miscible properties
with oils and under certain conditions of temperature
and pressure can cause fractionation of a HFC blend
eg. R407C. Under these exceptional circumstances
the fractionation can lead to a change in composition
of the circulating blend and a change in system
performance. However, these circumstances are
unlikely to arise with equipment operating at
temperatures and pressures of typical refrigeration
systems used in building air conditioning systems.
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