FRCC.PC.017.A1.02
16
A
PPLICATION
GUIDELINES
S
YSTEM
DESIGN
RECOMMENDATIONS
Essential piping design
considerations
Proper piping practices should be employed to
ensure adequate oil return, even under minimum
load conditions with special consideration given
to the size and slope of the tubing coming from
the evaporator. Tubing returns from the evapora-
tor should be designed so as not to trap oil and to
prevent oil and refrigerant migration back to the
compressor during off -cycles.
If the evaporator lies above the compressor, the
suction line must have a loop at the evaporator
outlet to prevent refrigerant from draining into
the compressor during off -cycles.
If the evaporator were situated below the com-
pressor, the suction riser must be trapped so as
to prevent liquid refrigerant from collecting at the
thermal bulb location (see fi g. 1).
When the condenser is mounted at a higher po-
sition than the compressor, a suitably sized «U»-
shaped trap close to the compressor is necessary
to prevent oil leaving the compressor from drain-
ing back to the discharge side of the compressor
during off cycle. The upper loop also helps avoid
condensed liquid refrigerant from draining back
to the compressor when stopped (see fi g. 2). The
maximum elevation diff erence between the in-
door and outdoor section cannot exceed 8 m.
System manufacturers should specify precau-
tions for any applications that exceed these limits
to ensure compressor reliability.
Piping should be designed with adequate three-
dimensional fl exibility. It should not be in contact
with the surrounding structure, unless a proper
tubing mount has been installed. This protection
proves necessary to avoid excess vibration, which
can ultimately result in connection or tube failure
due to fatigue or wear from abrasion. Aside from
tubing and connection damage, excess vibration
may be transmitted to the surrounding structure
and generate an unacceptable noise level within
that structure as well (for more information on
noise and vibration, see the section on: "Sound
and vibration management").
General
Successful application of scroll compressors is
dependent on careful selection of the compres-
sor for the application. If the compressor is not
correct for the system, it will operate beyond the
limits given in this manual. Poor performance, re-
duced reliability, or both may result.
0.5 % slope,
4 m/s or more
0.5 % slope,
4 m/s or more
U-trap
U-trap, as short as possible
U-trap, as short as possible
max. 4 m
fig.1
max. 4 m
8 to 12 m/s
To condenser
Evaporator
Condenser
HP
U-trap
3D flexibility
Upper loop
LP
fig. 2
