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c. Suction-tube temperature (F) at low-side service
fitting.
d. Suction (low-side) pressure (psig).
5. Using ‘‘Superheat Charging Table,’’ compare outdoor-air
temperature (F db) with evaporator inlet-air temperature
(F wb) to determine desired system operating superheat
temperature. See Tables 5A-5I and 6A-6F.
6. Using ‘‘Required Suction-Tube Temperature (F)’’
table, compare desired superheat temperature with suc-
tion (low-side) operating pressure (psig) to determineproper
suction-tube temperature. See Table 7.
7. Compare actual suction-tube temperature with proper
suction-tube temperature. Using a tolerance of ±3° F, add
refrigerant if actual temperature is more than 3° F higher
than proper suction-tube temperature, or remove refrig-
erant if actual temperature is more than 3° F lower than
required suction-tube temperature.
NOTE: If the problem causing the inaccurate readings is a
refrigerant leak, refer to Check for Refrigerant Leaks sec-
tion on page 27.
Table 5A — Superheat Charging Table, 50SS018
TEMP (F)
AIR ENT
COND
EVAP AIR — CFM
600
Evap Air — Ewb (F)
54 56 58 60 62 64 66 68 70 72 74 76
65 SPH 17.3 18.5 19.6 20.8 24.2 27.7 28.5 29.3 29.3 29.3 29.3 29.3
70 SPH 13.8 14.9 16.1 17.3 20.7 24.1 25.7 27.3 27.3 27.3 27.3 27.3
75 SPH 10.2 11.4 12.5 13.7 17.1 20.6 22.9 25.2 25.2 25.2 25.2 25.2
80 SPH 8.2 8.8 9.5 10.2 13.6 17.0 20.1 23.1 23.9 24.1 25.4 26.1
85 SPH 6.1 6.2 6.5 6.6 10.0 13.5 17.3 21.1 22.6 24.1 25.6 27.1
90 SPH * * * 5.0 8.1 11.4 15.2 19.0 20.5 22.0 23.5 25.0
95 SPH ****6.29.413.2 17.0 18.5 20.0 21.5 23.0
100 SPH *****7.311.114.9 17.2 19.5 21.7 24.0
105 SPH *****5.39.112.9 15.9 18.9 21.9 24.9
110 SPH ******6.710.8 13.8 16.8 19.8 22.8
115 SPH *******8.811.814.8 17.8 20.8
LEGEND
Ewb — Entering Wet Bulb
SPH — Superheat at Compressor (F)
*Do not attempt to charge system under these conditions — refrigerant slugging may occur.
Table 5B — Superheat Charging Table, 50SS024
TEMP (F)
AIR ENT
COND
EVAP AIR — CFM
800
Evap Air — Ewb (F)
54 56 58 60 62 64 66 68 70 72 74 76
65 SPH 18.2 19.0 19.9 20.7 22.5 24.2 25.1 25.9 26.6 27.2 27.9 28.6
70 SPH 17.1 17.6 18.1 18.6 20.4 22.1 23.0 23.9 24.9 26.0 27.1 28.1
75 SPH 16.0 16.2 16.4 16.6 18.3 20.1 21.0 21.8 23.3 24.8 26.2 27.7
80 SPH 14.8 14.7 14.6 14.5 16.3 18.0 19.7 21.3 22.4 23.5 24.6 25.8
85 SPH 13.7 13.3 12.9 12.5 14.3 16.0 18.4 20.7 21.5 22.3 23.1 23.8
90 SPH 11.1 10.9 10.7 10.4 12.2 13.9 16.3 18.7 19.9 21.0 22.2 23.4
95 SPH 8.5 8.4 8.4 8.4 10.1 11.9 14.3 16.6 18.2 19.8 21.4 23.0
100 SPH 7.3 7.5 7.7 7.9 8.9 9.9 12.2 14.6 16.6 18.6 20.6 22.6
105 SPH 6.2 6.6 6.9 7.3 7.6 7.8 10.2 12.5 14.9 17.3 19.7 22.1
110 SPH * * * 5.3 5.5 5.8 8.1 10.5 13.3 16.1 18.9 21.7
115 SPH ******6.18.411.614.9 18.1 21.3
LEGEND
Ewb — Entering Wet Bulb
SPH — Superheat at Compressor (F)
*Do not attempt to charge system under these conditions — refrigerant slugging may occur.
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