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Volkswagen Golf Mk7 Service & Repair Manual: Vapour pressure table for refrigerant R134a

This page introduces the R134a vapour pressure table used throughout Volkswagen Golf Mk7 AC diagnostics — showing the pressure exerted on the liquid refrigerant at a given temperature.

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

    Questions & answers

    Vapour pressure table for refrigerant R134a — Volkswagen Golf Mk7

    What is the R134a vapour pressure table in the Golf Mk7 manual?
    A lookup table showing the relationship between temperature and pressure for R134a refrigerant. Technicians use it to diagnose circuit pressures at a given ambient temperature.
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