1
Refrigerating Specialties Division
Description
All A4 type regulators are pilot operated using upstream
pressure for the opening force and require a minimum 2
psi (0.14 bar) pressure drop to fully open.
These valves are generally ordered with close coupled
upstream strainer to prevent entrance of foreign
material into the valve and the rest of the system.
Purpose:
These pneumatically compensated inlet pressure
regulators modulate the flow of refrigerant gas or liquid
to maintain a varying upstream (or inlet) pressure in
response to a pneumatic signal received from a
pneumatic controller. The regulator set-point will be
directly varied, on a 1:1 basis (A4AP) or 3:1 basis
(A4A3P), with value of the air pressure supplied to the
bonnet. Thus a pneumatically compensated regulator,
by responding to the varying output air signal from a
pneumatic controller, can change the evaporator
pressure and temperature up and down to match a
varying load condition. A 1 psi increase in air pressure
will increase the set point by 1 psi for the A4AP and 3
psi for the A4A3P. Generally, the pnuematic controller
modulates the air pressure from 3 to 15 psig throughout
its control range.
PNEUMATICALLY COMPENSATED
INLET PRESSURE REGULATORS
TYPE A4AP-DN, A4A3P-DN
Port Size 3/4"- 4" (20 - 100 mm)
For Ammonia, R22, R134a, R404a, R507
Other Refrigerants and Oils
FEATURES
• Pilot operated characterized Modulating Plug for
precise control
• Suitable for all common refrigerants and oils
•
406
psig (2
8
bar) design pressure (PS)
• Flanges for threaded or welded steel pipe and copper
tube (copper not for ammonia)
• Unique modular construction
• Interchangeable parts
• Easy to service
• Close coupled strainers, optional
• Stainless Steel Diaphragm
• Manual opening stem
• Complies with Pressure Equipment Directive 97/23/EC
Pressure Ranges:
• A: 0-150 psig (0-10 bar)Standard
• D: 75-280 psig (5-19 bar)A4AP only
• V: 20 in. hg-120 psig (500 mm hg- 8.3 bar)
BULLETIN DN23-08
B
Type A4AP-DN, A4A3P-DN
January 2007
Installation and Service Information
A4A3P-DN
Fig. 1 A4AP
I S O 9 0 0 1 C E R T I F I E D
310216
