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Manage operating envelope
Discharge temperature
protection
32
AB444226142054en-000101
Discharge gas temperature (DGT) protection
is required if the high and low pressure switch
settings do not protect the compressor against
operations beyond its specific application
envelope. Please refer to below R404A examples
70
65
60
55
50
45
40
35
30
25
20
15
10
5
0
-35
-30
Example 1 (R404A, SH=10K)
LP switch setting:
LP1=2bar(g) (-20°C)
HP switch setting:
HP1=26.5bar(g) (58°C)
Risk of operation beyond the application envelope.
DGT protection required
Continuous operations beyond the compressor's
operating range will cause serious damage to the
compressor.
The discharge gas thermostat accessory kit (code
7750009) includes all components required
for installation as shown on the right. DGT
installation must respect below requirements:
• The thermostat must be attached to the
discharge line within 150 mm (5.91 inch) from
the compressor discharge port and must be
thermally insulated and tightly fixed on the
pipe.
below, which illustrate where DGT protection is
required (Ex. 1) and where it is not (Ex. 2). Please
notice the envelope boundaries change based
on different speed limits.
-25
-20
-15
-10
-5
Evaporating temperature (°C)
Example 2 (R404A, SH=10K)
LP switch setting:
LP2=2.6bar(g) (-15°C)
HP switch setting:
HP2=22bar(g) (50°C)
No risk of operation beyond the application envelope
• The DGT should be set to open at a discharge
gas temperature of 135°C (275°F) or lower.
Discharge line
LP1
LP2
0
5
10
15
20
OE-000068
Thermostat
Insulation
Bracket
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