Brochure

Parker Hannifin Corporation
Climate & Industrial Controls Group
Cleveland, OH
Catalog CIC-2003-1/US
Thermostatic and Constant Pressure (Automatic) Expansion Valves
180
Constant Pressure (Automatic) and EPR ValvesApplications
Crankcase Pressure Limiting
Parker constant pressure expansion valves can be
used to limit the maximum operating suction pressure
to the compressor. The valve is adjusted to open at a
predetermined outlet pressure while restricting flow at
higher system inlet pressures in order to protect the
compressor. Non-bleed type valves are recommended
for this type application.
EPR - Ice Cream Machine
Parker Model 139 EPRs are specifically designed for
fractional horsepower evaporator applications where
precise control of evaportor pressure is required when
using a primary expansion device. A typical application
is in a multiple evaporator system where different
evaporator pressures and temperatures are desired.
The 139 EPR may be used to control at a higher
evaporator pressure then is present at the compressor
suction.
Hot Gas Bypass to Evaporator Inlet
Constant pressure expansion valves control hot gas
bypass in systems where temperature is extremely
critical and load conditions vary widely – particularly
low loads. Installed between the discharge line and the
evaporator, the valve controls pressure precisely. As the
load drops, evaporator pressure decreases. It throttles
open to maintain outlet pressure. This action maintains
the temperature of the evaporator. This application may
also be used as freeze protection.