Specifications

Part Number STH12 9/10 161
Operating Pressures
NORMAL OPERATING PRESSURES OF
REFRIGERATION UNITS
1. On system with expansion valve (pressure
limiting) evaporator gets no higher than:
50 psig on R-12
53 psig on R-502
85 psig on R-22
2. Water system head pressure should be manually
set (adjustable water control valve) to maintain
105°F water condenser out temperature.
3. Remote Condenser system head pressure will be
controlled by Low Ambient Control
75 psig on R-12, R-134A
150 psig on R-502, R-22, R-404A
R-12 R-502 R-22 R-134A R-404A
Head Pressure psig psig psig psig psig
75°F Condenser
Ambient
10-100% Ice on
Evaporator
100-140 200-260 180-240 110-160 210-280
90°F Condenser
Ambient
10-100% Ice on
Evaporator
120-170 230-300 210-280 130-180 240-320
R-12 R-502 R-22 R-134A R-404A
Evaporator Pressure psig psig psig psig psig
75°F Evaporator,
or 80°F Water
75 140 130 75 150
10-100% Ice on
Evaporator
9-20 30-50 24-44 9-20 33-55