Volkswagen Golf Service & Repair Manual: Vapour pressure table for refrigerant R134a

Volkswagen Golf Service & Repair Manual / Air conditioning system with refrigerant R134a / General notes on air conditioning systems / Basics of air conditioning / Vapour pressure table for refrigerant R134a

The vapour pressure table for each refrigerant is published in the literature for refrigeration engineers. This table shows the vapour pressure exerted on the liquid column in the container for a given temperature of the container.

Since a characteristic vapour pressure table is known for every refrigerant, one can determine what refrigerant is present by measuring pressure and temperature.

Note

Absolute pressure means that 0 bar corresponds to an absolute vacuum. The normal ambient pressure (positive pressure) corresponds to 1 bar absolute pressure. On most pressure gauges, a reading of 0 bar corresponds to an absolute pressure of one bar (which is confirmed by the existence of a -1 bar marking beneath the 0 scale marking).

Temperature in °C	Pressure in bar (positive pressure) R134a
-45	-0.61
-40	-0.49
-35	-0.34
-30	-0.16
-25	0.06
-20	0.32
-15	0.63
-10	1.00
-5	1.43
0	1.92
5	2.49
10	3.13
15	3.90
20	4.70
25	5.63
30	6.70
35	7.83
40	9.10
45	10.54
50	12.11
55	13.83
60	15.72
65	17.79
70	20.05
75	22.52
80	25.21
85	28.14
90	31.34

Pressure and boiling point

The boiling points given in the table below are always based on an atmospheric pressure of 1 bar. If the pressure on a liquid is changed, its boiling point changes al ...

Refrigerant R134a

Air conditioners in vehicles use the evaporation and condensation process. The system contains a liquid with a low boiling point, called the refrigerant. ...

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