Refrigerating Specialties Division
5
The pressure on top of the Piston is controlled by the fl ow through
the Pilot Plug and the bleed through the bleed hole in the Piston.
Due to the Seal Ring fi tted to the Piston, the amount of bleed to
the outlet of the valve, as a result of blow-by of the Piston, is very
small. A minimum pressure drop of 0.14 bar (2 psi) across the valve
is required to open it fully.
The Type A4WOE Outlet Pressure Regulator opens on a drop
in outlet pressure below set-point and closes on a rise in outlet
pressure above its set-point. The outlet pressure set-point is not
appreciably affected by variations in the inlet pressure.
Adjustment
See Outlet Pressure Regulator Adjustment on page 2.
Type A4WR (See Fig. 6)
Description
The Type A4WR is a main valve only intended for pilot operation by
one or more remote piloting devices, such as Type S6N Solenoid
Valve, Type A2B (inlet) or Type A2BO4E (outlet) Pilot Regulators.
The valve is complete with a Manual Opening Stem but has no
integrally mounted pilot devices to provide any type of control
function. A plain Cover with a 3/8” FPT connection is in the position
otherwise occupied by the pilot devices. The
Type A4WR uses upstream pressure which is externally fed to
the A4WR through pipes (not included with valve) fi eld installed to
provide the moving force for the valve operation. A minimum 0.14
bar (2 psi) pressure drop is required to fully open the valve. The
upstream pressure must be fed from a connection fi eld installed in
the main valve inlet pipe. There is no connection on the valve body
for this purpose.
A small fl ow of refrigerant passes through the line connected to
the upstream side of the valve so care must be used not to create a
pressure drop by under sizing the pipe or using too great a length.
Normally standard 3/8” US pipe size no longer than 6m (20 ft.) will
be adequate. Consult the factory if a greater length is required.
Purpose
The Type A4WR should be used where there is an advantage to install
all of the control modules at some remote location. Frequently this
is done to make adjustment and servicing easier, or to fi t a large
valve in a space that would be too small for a complete valve.
Principles of Operation
Since the Type A4WR is a main valve only and may be used with an
assortment of remote devices: the reader is referred to the most
recent editions of the bulletins describing each of those devices.
The most common of these are: Type S6N Solenoid Valve - Bulletin
30-90; Type A2B and Type A2BO4E Regulators - Bulletin 21-02.
Adjustment
See the appropriate bulletin as listed above under “Principles of
Operation”.
Installation
It is necessary that all installation personnel read and become
familiar with the Refrigerating Specialties Division’s Refrigeration
Safety Bulletin (RSB) before installing any valves.
All valves are packed for the maximum protection during storage
and shipment Read the literature packed with the valve and save it
for reference after installation.
Do not remove the protective covers from the inlet and outlet of the
valve until ready to install, as they protect the interior from dirt and
other foreign matter.
Select a location for installation where the valve will be easily
accessible for adjustment and maintenance and where a pressure
gauge installed on the regulator can be seen. Avoid locations where
the valve may be damaged by personnel, traffi c, material handling or
other equipment.
Before installing the valve, check to see that all chips, scale,
dirt, moisture and other foreign material are removed from the
connecting pipes. Be sure the arrow on the A4W valve body is
pointing in the direction of fl uid fl ow for the regulator to function
properly. Backward fl ow through the regulator is uncontrolled and
will vary with the reverse pressure drop encountered. The regulator
is NOT a check valve. Remove the protective covers from the valve. It
is not necessary to disassemble or to manually open the valve before
welding in place.
The A4W family of regulators will give optimum performance if
mounted in a horizontal line in a vertical position with the Manual
Opening Stem on the top. This is particularly true for regulators with
an electrical feature, such as the “B”, “S” or “D” variations. Where
other positions are desired, the factory should be consulted; please
give valve type, application and piping details.
After installation, check the valve and the welded joints for external
leaks with refrigerant or other appropriate gas before putting the
system into operation
If pilot solenoid valves are a part of the regulator, connect the
solenoid lead wires to an electrical supply source the same as
indicated on the valve coil. The power source must be capable of
supplying full, constant voltage. The wires to which the solenoid
leads are connected must be of the proper gauge.
When it is necessary to insulate the regulator (and companion
strainer), the insulation should be installed to allow access to the
regulator (and companion strainer) for adjustment and maintenance.
Do not insulate a solenoid coil and coil housing. Proper indicating
gauges should be installed to be easily visible to the operating
engineer for system checking and adjusting purposes.
Electrical (For A4WS, A4WB and A4WD)
The Refrigerating Specialties Division molded, water resistant Class
“B” solenoid coil is designed for long life and powerful opening force.
The standard coil housing meets NEMA 3R and 4 requirements. This
sealed construction can withstand direct contact with moisture and
ice. The coil housing far exceeds the requirements of NEMA Standard
ICS, 1-110.57 salt spray test for rust resistance.
By defi nition, Class “B” coil construction will permit coil internal
temperatures, as measured by the resistance method, as high as 130
deg. C (266 deg. F). Final coil temperatures are a function of both fl uid
and ambient temperatures. The higher fl uid temperatures require
lower ambient temperatures so the maximum coil temperature is
not exceeded.
Conversely, low fl uid temperatures permit higher
ambient temperatures.
The molded Class “B” coil is available, from Refrigerating Specialties
Div. stock, with most standard voltages. However, coils are available
for other voltages and frequencies, as well as for direct current.
Coils are also available as transformer type with a 6 volt secondary
winding for use with the Refrigerating Specialties Division Pilot Light
Assembly. (See current copy of Bulletin 60-10, “Pilot Light Assembly
and Solenoid Transformer Coil”.)
The solenoid coil must be connected to electrical lines with volts
and Hertz the same as stamped on the coil. The supply circuits must
be properly sized to give adequate voltage at the coil leads even
when other electrical
equipment is operating. The coil is designed to
Fig. 6 - A4WR
