Engineered air PD SERIES, Installation, Operation And Maintenance Manual

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PD MANUAL
IOM-39 21 of 36 Aug 99 R1
6. solenoid drop, or
7. single pumpdown, or
8. recycling pumpdown, depending on the specific application.
9. Hot Gas Bypass (Optional):
Hot gas bypass is provided on systems to prevent frost formation on the evaporator coil during low
load conditions. The hot gas valve will start to open at a pressure that corresponds to
approximately 34°F (1°C) coil temperature. All compressors equipped with unloading should be
fully unloaded before hot gas starts to open.
10. Cylinder Unloading (Optional)
This is a form of capacity control on some compressors that reduces the pumping capacity of the
compressor during low load conditions. Unloading may be activated by the control system or by a
pressure actuated Cylinder Unloading Control (CUC).
11. Water Cooled Systems (Optional)
If the system is equipped with a water cooled condenser, set the water flow valve to maintain a
saturated discharge temperature of approximately 105°F to 115°F (40°C to 46°C). This applies both
to cooling tower systems and city water systems.
Typical water valve pressure setting:
R134a = 150 psig (1040 kPa)
R407C = 270 psig (1870 kPa)
R410A = 370 psig (2550 kPa)
Caution: When recovering refrigerant from a system equipped with a water cooled condenser, the
water valve must be manually opened so water flows continuously through the condenser
while the refrigerant is being recovered. Failure to do so can cause the condenser to
freeze, which will permanently damage the condenser.
REFRIGERANT HANDLING
Recovery, reuse, recycling, reclamation, and safe disposal of refrigerant is the only acceptable practice
today. Venting of refrigerant into the atmosphere during installation or servicing is unacceptable. To
avoid damage, use an accepted refrigerant recovery system whenever removing refrigerant. When
working with refrigerants you must comply with all local government safety and environmental laws.
Caution: Environmental laws govern the safe handling of refrigerants. Only personnel qualified to
safely handle refrigerant may service this equipment. All refrigerant must be handled
safely and responsibly. Records must be kept as required by the authorities having
jurisdiction.
When servicing the refrigeration system, the refrigerant must be properly recovered to prevent release to
atmosphere. Always use the same refrigerant as indicated on the unit rating plate.