Operating conditions
R404A /
R507A
R452A
R454C
R455A
Working pressure range, high side
(bar gauge)
13.2 – 27.7 12.5 – 24.2 5.2 – 22.3 5.6 – 24.3
Working pressure range, low side
(bar gauge)
0.05 – 3.3
0.18 – 3
0.05 – 2.2 0.12 – 2.4
Minimum low pressure safety switch setting
(bar gauge)
0
0.13
0
0
Minimum low pressure pump-down switch setting (bar gauge)
0.21
0.35
0.21
0.21
Relief valve opening pressure difference (2 and 4 cyl)
(bar)
30
30
30
30
Relief valve closing pressure difference
(bar)
8
8
8
8
Low pressure
Operating limits
High pressure
R
A low-pressure (LP) safety switch must
also be used; deep vacuum operations will result
in failure. The minimum LP safety switch (loss
of charge switch) setting is 0 relative bar (0 bar
g). For systems without pump-down feature,
the LP safety switch must be either a manual
lockout device or an automatic LP safety switch
wired into an electrical lockout circuit. LP switch
tolerance must not allow for vacuum operation
of the compressor. LP safety switch settings for
pump-down cycles with automatic reset are
listed in the following table.
A high-pressure (HP) safety switch is required to
shut down the compressor should the discharge
pressure exceed the values shown in the table
below. This switch can be set at lower values
depending on the application and ambient
conditions. It must be either located in a lockout
circuit or associated with a manual reset device
to prevent cycling around the high pressure limit.
If a discharge valve is used, the HP switch must
be connected to the service valve gauge port,
which cannot be isolated.
Thermostat
Insulation
Bracket
Discharge line
Discharge temperature
protection
R
Even when the motor windings are
protected against overheating by the internal
motor protection, the compressor discharge
gas temperature could exceed the maximum
allowed value of 135°C when the compressor
is operated outside its application envelope.
The most effective protection against too
high discharge gas temperature is to mount
a discharge gas thermostat. An accessory kit
is available from Danfoss which includes the
thermostat, mounting bracket and insulation.
The thermostat must be attached to the
discharge line as indicated below at no more
than 150 mm from the discharge connection.
AB245486497018en-000601
20
Application Guidelines