REGULATOR VARIATIONS
NOTE:
Many other control functions can be achieved by
combining the control modules in different arrangements.
For example: a dual regulator with electric shut-off on
each pressure pilot; i.e. HA4ADS.
HA4AP
HA4AT
HA4AJ
HA4AO
HA4A
HA4AS
HA4AB
HA4AD
HA4AL
HA4AK
HA4AM
HA4A STANDARD REGULATOR
This most common pressure regulator
modulates to control evaporator pressure,
condensing pressure, pressure in a
ve s s e l, or pr e s sur e in a por tion of
a system. It is frequently called an
evaporator pressure regulator (EPR) or
back pressure regulator. Opens on rising
inlet pressure. See page 8. Shown with
M3W pilot.
HA4AS REGULATOR WITH
ELECTRIC SHUT-OFF
T h i s c o n t r o l i s c o m m o n l y u s e d fo r
temperature control or defrost. Regulates
at the set-for pressure when energized.
When de-energized, the valve closes
tight regardless of the pressure setting.
See page 9.
HA4AB REGULATOR WITH
ELECTRIC WIDE OPENING
C o m m o n l y r e g u l a te s fo r d e f r o s t o r
temperature, but opens wide for maximum
cooling. Regulating at the set-for pressure
when de-energized; regulator opens when
energized. See page 9.
HA4AD DUAL PRESSURE
REGULATOR
Regulates (evaporator) pressure at a
setting when energized, and at a higher
setting for defrost, temperature control,
or pressure relief when de-energized.
See page 9.
HA4AL DIFFERENTIAL
PRESSURE REGULATOR
Commonly used as liquid pump relief,
condenser-receiver pressure difference
control, discharge pressure boosting
for defrosting or heat recover y, and
other similar applications. This control
m o d u l a t e s t o m a i n t a i n t h e s e t- f o r
dif fer ence bet we en inlet a nd outlet
pressure. See page 8.
HA4AK RESEATING
RELIEF REGULATOR
Used for defrost, high-to-low side relief,
or nonatmosphere relief to other parts
of the system. This control opens when
system upstream pressure is above the
tagged and sealed set point pressure,
and repeatedly reseats after operation.
See page 8.
HA4AO OUTLET
PRESSURE REGULATOR
Controls outlet pressure by opening
a s downstream pressure falls below
t h e s e t p o i n t . U s e d f o r h o t g a s t o
provide artificial refrigeration loading, for
condenser and receiver pressure control
by means of gas bypass, limiting hot gas
pressure supply in defrosting evaporator in
conjunction with liquid drain traps, or for
compressor suction pressure limitation.
Can be combined with electric shut-off,
temperature-operated, dual, or wide-
opening features. See page 9.
HA4AP PNEUMATICALLY
COMPENSATED REGULATOR
Commonly used for precise air or liquid
t e m p e r a t u r e c o n t r o l v i a p n e u m a t i c
controller. An air, vapor, or liquid pressure
signal to the control module bonnet
increases inlet pressure from the set-for
pressure value at a 1:1 ratio. See page 10.
HA4AT TEMPERATURE
OPERATED REGULATOR
The vapor pressure capillary tubing and
bulb system modulates the regulator open
as temperature increases to control air or
liquid temperature. See page 10.
HA4AJ ELECTRONICALLY
CONTROLLED REGULATOR
Electronic pilot and controller provides
ve r y p r e c is e te m p e r atu r e c o nt r o l of
various cooled media under fluctuating
load conditions. See page 10.
HA4AM ELECTRIC MOTOR
COMPENSATED REGULATOR
C o m m o n l y u s e d f o r p r e c i s e r o o m
temper atur e contr ol or liquid chiller
control. The controlling motor changes
regulator pressure setting in accordance
with a temperature controller. See page 11.
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R429d
AUG 2015