Refrigerant Charge Limits And Compressor Protection - Danfoss Performer SM Series Selection & Application Manuallines

sYsteM design RecoMMendations
Refrigerant charge limits
and compressor protection
Compressor models
Refrigerant charge limit (lb)
cooling only systems, Rec
packaged units
ReQ
cooling only systems
with remote condensor
and split system units
Reversible heat pump system
The DGT should be set to open at
a discharge gas temperature of 275
Notes: The compressor must not be
allowed to cycle on the discharge gas
thermostat. Continuous operation
160
155
150
145
140
135
130
125
120
115
110
105
100
95
90
85
80
75
70
65
-15 -10 -5
example 1 (R-22, SH = 20
LP switch setting:
LP1 = 26 psig (1°F)
HP switch setting:
HP1 = 363 psig (144°F)
Risk of operation beyond the application
envelope.
DGT protection required.
The refrigerant charge limits given in
the table below will help to evaluate
the need for compressor protection
note: for reversible heat pump sys-
S 0 84 - 090
S 110 - 120
- 100
18.8 22.0
Rec
Rec
BeloW charge limit
ReQ
ReQ
No test or additional safeties required
Rec
Rec
ReQ ReQ
Rec
ReQ
Rec ReQ ReQ
Refrigerant migration & floodback test
Rec Crankcase heater, because full system ReQ Rec
Rec
charge is not definable (risk of overcharging)
ReQ
Rec
Rec
Rec
ReQ
Rec
Recommended
No test or additional safeties required
ReQ
The above chart represents basic
guidelines for reliable compressor
operations and safety. Please contact
F
o
Example 1
Example 2
LP 1 LP 2
0 5 10 15 20 25 30
Evap. Temp. (°F)
o F)
S 148 - 160
S 115 - 125
- 161
24.0 27.5
ReQ ReQ
Rec ReQ ReQ
ReQ ReQ ReQ
ReQ
Rec Rec
ReQ ReQ ReQ
ReQ
ReQ Rec
ReQ ReQ
ReQ
Rec ReQ ReQ
Rec ReQ Rec
ReQ ReQ ReQ
Specific tests for repetitive floodback
ReQ Crankcase heater ReQ ReQ
Rec
ReQ Rec
Discharge gas thermostat
ReQ
ReQ
Rec ReQ Required
Rec ReQ
ReQ
Rec ReQ
Rec ReQ
beyond the compressor's operating
range will cause serious damage to
the compressor!
A DGT accessory is available from
Danfoss: refer to page 35.
HP 1
HP 2
R410A
35 40 45 50 55 60
example 2 (R-22, SH = 20 o F)
LP switch setting:
LP2 = 42 psig (19°F)
HP switch setting:
HP2 = 305 psig (131°F)
No risk of operation beyond the application
envelope.
No DGT protection required.
tems and other specific applications,
please refer to section "Specific
Application Recommendations".
S 175 - 185 S 240
29.8 35.0
aBoVe charge limit
ReQ
ReQ
Refrigerant migration & floodback test
Crankcase heater
ReQ
Refrigerant migration & floodback test
ReQ
Crankcase heater
Liquid receiver
ReQ ReQ
ReQ
ReQ ReQ
Rec ReQ
Rec
ReQ ReQ
Rec ReQ
Danfoss technical support for any
ReQ ReQ
deviations from these guidelines.
Rec
S 300 - 380
44.0
ReQ ReQ
ReQ ReQ
Rec
19