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Pressure-Temperature Relationship

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A refrigerant, when confined in an enclosed space, increases in pressure as the temperature increases. Conversely, if the temperature is lowered, the pressure also decreases.

Depending on temperature, a corresponding pressure will exist in such an enclosed space. For example, at 70°F (21.1°C) a gauge will indicate about 71.0 psi (5.0 kg/cm2 ). The R-134a PRESSURE-TEMPERATURE RELATIONSHIP  table shows this relationship.

R-134a PRESSURE-TEMPERATURE RELATIONSHIP

Temperature °F (°C) (1) psi (kg/cm2 )
20 (-6.7) 18 (1.3)
30 (-1.1) 26 (1.8)
40 (4.4) 35 (2.5)
45 (7.2) 40 (2.8)
50 (10.0) 45 (3.2)
55 (12.8) 51 (3.6)
60 (15.6) 57 (4.0)
65 (18.3) 64 (4.5)
70 (21.1) 71 (5.0)
75 (23.9) 79 (5.6)
80 (26.7) 87 (6.1)
85 (29.4) 95 (6.7)
90 (32.2) 104 (7.3)
95 (35.0) 114 (8.0)
100 (37.8) 124 (8.7)
110 (43.3) 147 (10.3)
120 (48.9) 171 (12.0)
130 (54.4) 199 (14.0)
140 (60.0) 229 (16.1)
150 (65.6) 263 (18.5)
160 (71.1) 300 (21.1)
(1) Pressure readings are provided as a general guideline and may not represent actual readings.