Refrigerant R134a

Refrigerant R134a

Vehicle air conditioning systems make use of the vaporization and condensation process. Use is made of a substance with a low boiling point, which is called refrigerant.

The refrigerant employed is tetrafluoroethane R134a, which boils at -26.5 degree C at a vapor pressure of 1 bar.

Physical data of refrigerant R134a
Chemical formula CH2FCF3 or CF3CH2F
Chemical designation Tetrafluoroethane
Boiling point at 1 bar -26.5 degree C
Solidification point -101.6 degree C
Critical temperature 100.6 degree C
Critical pressure 40.56 bar (absolute)

Critical point
The critical point (critical temperature and critical pressure) is that above which there is no longer a boundary between liquid and gas.

A substance above its critical point is always in the gaseous state.

At temperatures below the critical point, all types of refrigerant in pressure vessels exhibit both a liquid and a gas phase, i.e. there is a layer of gas above the liquid.

As long as both liquid and gas are present in the vessel, the pressure is governed by ambient temperature.

NOTE: Different types of refrigerant are never to be mixed. Only the refrigerant designated for the corresponding A/C system may be used.

Environmental aspects of refrigerant R134a
- R134a is a fluorocarbon and contains no chlorine.
- R134a has a shorter atmospheric lifespan than refrigerant R12.
- R134a does not deplete the ozone layer.
- The global warming effect of R134a is ten times less than that of refrigerant R12.