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Regulators

Emerson Climate Technologies

EVAPORATOR

PRESSURE

REGULATOR

EVAPORATOR

PRESSURE

REGULATOR

EXTERNAL

STRAINER

RECOMMENDED

NOTE: HIGH SIDE PILOT

PRESSURE REQUIRED

FOR EPRBS

NOTE: HIGH SIDE PILOT

PRESSURE REQUIRED

FOR EPRBS

EXTERNAL

STRAINER

RECOMMENDED

60 PSIG

HIGH

EVAPORATOR

PRESSURE

50 PSIG

INTERMEDIATE

EVAPORATOR

PRESSURE

20 PSIG

LOW

EVAPORATOR

PRESSURE

Types of Regulators:

Suction Line Regulators

Suction line regulators provide a wide variety of re-

frigerant control functions, but are mainly used for regu-

lating suction gas pressures. These regulators provide

a method of balancing the output of the refrigeration

system with the load requirements. Two basic types are

covered here:

1) Upstream pressure regulators, which control from an

inlet pressure signal.

2) Downstream pressure regulators, which control from

an outlet pressure signal.

Application of

Evaporator Pressure Regulators

Evaporator Pressure Regulators are normally used

on multiple-compressor refrigeration systems fed by

TXVs, low side oats or solenoid liquid valve and oat

switch combination. They are used whenever a mini-

mum evaporator pressure or temperature is desired.

Controlling from an inlet side pressure signal, they

prevent upstream pressure from going below a pre-set

point.

EPR valves are used on brine or water chillers to pre-

vent freeze-up during low load periods, by keeping the

refrigerant saturation pressure above the uid freezing

temperature. Similarly, they may be used to prevent frost

formation on fan coil evaporators. They may also be

used to provide a given evaporator saturation pressure

to produce the required evaporation/room temperature

difference, (especially useful where humidity control is

required). On multiple evaporator systems where differ-

ent evaporator temperatures are required, EPR valves

will hold the saturation pressure at the required set point

above the common system suction pressure. Here, the

EPRs prevent lowering of the desired temperature in the

warmer evaporators, while the compressor continues

operating to satisfy the coldest evaporators. See

gure 1.

Figure 1: Evaporator Pressure Regulators

used in multiple system.

EPR Installation

EPRs may be installed at the compressor rack or

close to the evaporator.

Suction line regulators can be direct acting or inter-

nally piloted such as an Emerson IPR regulator. These

are hermetically sealed, non-repairable valves for use

on low capacity systems.

For higher sensitivity and accurate control, an exter-

nally piloted EPRB regulator will provide control of larger

units. These are repairable in the line. The EPRB valve

is a lightweight, brass body valve which eliminates the

need for normal system pressure drop needed to make

the valve move through the full stroke. This is accom-

plished by using compressor discharge gas to pilot the

regulator.

Combining an EPRB with a suction stop or shut off is

done with the EPRBS models. When the pilot solenoid is

de-energized, the valve closes. This eliminates the cost

of a separate suction solenoid and offers a tight shut off.

Figure 2: Cutaway view of an EPRBS.

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