Brochure

Parker Hannifin Corporation
Climate & Industrial Controls Group
Cleveland, OH
Catalog CIC-2003-1/US
Refrigeration Solenoid Valves
250
Technical Information 3-Way Hot Gas Defrost Valves
3-Way Hot Gas Defrost Valves
RS65
Application
Designed for hot gas defrost from the suction side of the
evaporator coil, these valves are commonly used with
modern multiplex systems.
Operation
When de-energized, the plunger closes the pilot port,
allowing pressures to equalize across the piston. Discharge
pressure holds the lower port seat closed. Flow is from the
evaporator to the suction line. (See illustration below.)
Piston
Plunger
Piston
Evaporator
Line
Pilot Port
Suction Line
RS55, RS65
Suction Line
RS70
Integral
Bypass Tube
When energized, discharge pressure flows to the
top of the piston, creating a pressure imbalance
sufficient to move the piston, closing the suction
line to the evaporator and opening the discharge
line to the evaporator. High pressure gas then
flows from the discharge line to the evaporator,
raising the pressure and temperature in the
evaporator and defrosting the coil.
Note: When energized, there is a constant flow of
discharge gas into the suction line through the
equalizer port to permit flow from discharge line
to evaporator.
Note: Valves are not intended to be used in con-
junction with a stop valve directly in front of the
defrost valve. To ensure proper performance, you
must maintain a constant pressure supply to the
discharge port on the defrost valve.
Flow
Thermostatic
Expansion
Valve
Evaporator
Solenoid
Suction Header
RS65
Discharge Header
Connections
Discharge
Line
RS70
Discharge
Line
RS55 &
Valve Type
Evaporator
Line
Suction
Line
Discharge
Line
RS-55 1-1/8" ODF 1-1/8" ODF 7/8" ODF
RS-65
RS-70
1-3/8" ODF 1-3/8" ODF 7/8" ODF