Danfoss VZH052 Manual page 23

Design piping
General requirements
Proper piping practices should be employed to:
1. Ensure adequate oil return, even under
minimum load conditions (refrigerant speed,
piping slopes...). For validation tests see section
"Manage oil in the circuit".
0.5% slope
4 m/s (13 ft/s)
max. 4 m (13ft)
or more
U-trap,
as short as possible
8 to 12 m/s
(26 to 40 ft/s)
max. 4 m (13ft)
0.5% slope
4m/s (13 ft/s) or more
U trap, as short as possible
3. Piping should be designed with adequate
three-dimensional flexibility to avoid excess
vibration. It should not be in contact with the
surrounding structure, unless a proper tubing
mount has been installed. For more information
on noise and vibration, see section on: "Sound
and vibration management".
2. Avoid condensed liquid refrigerant from
draining back to the compressor when stopped
(discharge piping upper loop). For validation
tests see section "Manage off cycle migration".
General recommendations are described in the
figures below:
To condenser Upper loop
HP
LP
HP
Evaporator
4. The design in this guideline is for short circuit
application. However, for long circuit and split
system application, an oil separator and an
external non-return valve are mandatory to use.
Condenser
LP
3D exibility
AB237586440343en-000601
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