McQuay AGS 225D

OM AGSD-1 39
Circuit Functions
Calculations
Refrigerant Saturated Temperature
Refrigerant saturated temperature is calculated from the pressure sensor readings for each
circuit. The pressure is fitted to a curve made up of 12 straight-line segments. The points
used to define these segments are shown in the following tables.
Evaporator Pressure Conversion:
Pressure (PSI) Temperature (
o
F)
0 -15.0
7.1 0
19.0 20.0
34.7 39.0
50.7 54.0
70.4 69.0
99.6 87.0
129.2 102.0
166.8 118.0
205.4 132.0
246.5 145.0
320.0 165.0
428.5 188.1
Condenser Pressure Conversion:
Pressure (PSI) Temperature (
o
F)
0 0.6
17.5 18.5
31.5 35.9
50.0 53.7
76.0 73.4
115.0 95.6
161.5 116.2
185.0 125.2
260.0 149.2
284.5 155.9
349.5 172.0
365.5 175.5
428.5 188.1
Evaporator Approach
The evaporator approach is calculated for each circuit. The equation is as follows:
Evaporator Approach = LWT – Evaporator Saturated Temperature
Suction Superheat
Suction superheat is calculated for each circuit using the following equation:
Suction superheat = Suction Temperature – Evaporator Saturated Temperature