Parker A4W, A4WE, A4WB, A4WS, A4WD Service Manual
...
ADAPTOMODE WELD-END
PRESSURE REGULATORS
Types: A4W, A4WE, A4WS, A4WB,
A4WD, A4WP, A4WOE, A4WR
Port Size 125-200mm (5”-8”)
FOR AMMONIA, R12, R22, R502
AND OTHER COMMON REFRIGERANTS
FEATURES
• Cast Steel Body – Strong, Lightweight.
• Welds Directly in the Line – No Flanges.
• Removable Seat – Serviceable from Top Side.
• Streamlined Fluid Flow Pattern.
• Unique Modular Construction – Same Modules
as A4A Series.
• Interchangeable Parts.
• Easy to Service.
• Pilot Operated Characterized Modulating Plug for
Precise Control.
• Suitable for All Common Refrigerants and Oil.
• 27.6 bar (400 psig) Maximum Rated Pressure (MRP).
• Many Control Variations are Possible with the Use
of a Few Modules and Kits.
• Stainless Steel Diaphragm.
• Chrome Plated Pilot Seat.
• Manual Opening Stem.
Seal Cap
Seal Cap
Manual
Opening
Stem
Power
Piston
Removable Seat
Fig. 1 - A4W, A4WE
Adjusting Stem
Range Spring
Diaphragm
Gauge Port
Pilot Seat
Modulating
Plug
Closing
Spring
BULLETIN 23-20D
A4W Series
August 2007
Installation, Service and Parts Information
Index
Item ...................................................................................... Page
A4W .............................................................................................1
A4WB ...........................................................................................3
A4WD ............................................................................................4
A4WE ........................................................................................... 2
A4WOE ......................................................................................2, 4
A4WP ............................................................................................4
A4WR ............................................................................................5
A4WS ............................................................................................3
Adjustment, Range ......................................................................2
Assembly ......................................................................................6
Dimension Drawings ............................................................ 12, 13
Disassembly ................................................................................. 6
Electrical ......................................................................................5
Installation ...................................................................................5
Mintenance and Service ...............................................................8
Manual Opening Stem ............................................................ 8, 9
Pressure Setting Ranges .............................................................2
Safe Operation .......................................................................... 14
Torques, Fastener and Seat ........................................................7
Trouble Shooting ........................................................................ 9
Warning .....................................................................................14
Warranty .....................................................................................14
Description
These heavy duty, cast steel bodied (ASTIM No. A352 Grade
LCB), pressure regulators weld directly in the line and do not
require fl anges.
They are used for control of Ammonia, R-12, R-22 and R-502,
and other common refrigerants, certain oils and other fl uids
approved for use in refrigeration systems.
The A4W Series Regulators are pilot operated, using upstream
pressure for the moving force, and require a minimum 0.14 bar
(2 psi) pressure drop to fully open. The basic Type A4W is an Inlet
Pressure Regulator which tends to open on a rise in upstream
pressure above set-point and to close on a drop in pressure
below set-point.
These valves can be ordered with the Type RSW Strainer to be
welded directly to the inlet of any of the Type A4W Regulators
or use a 13mm (1/2”) Type RSF Strainer in only the pilot circuit
of a Type A4WE or A4WR version of the regulator.
The A4W Series of regulators uses the same Modules as does
the A4A Series to confi gure many possible variations.
Refrigerating Specialties Division
050405
1
ISO 9001:2000 CERTIFIED
Purpose
The purpose of the Type A4W Series of Pressure Regulators is to
modulate the fl ow of refrigerant gas and/or liquid so as to maintain
a constant set for pressure, regardless of load fl uctuations. The
regulators described in this bulletin control upstream (inlet)
pressure except for the Type A4WOE, which controls downstream
(outlet) pressure.
The fl uid temperature range for the A4W Family of Regulators is
-45° to 105°C (-50° to 220°F).
Principles of Operation (See Fig. 1)
The inlet pressure enters the space under the Diaphragm through
passage N. When the force created by the pressure exceeds the
force of the Range Spring, the Diaphragm is lifted off of the Pilot
Seat, allowing pressure to enter on top of the Power Piston.
This causes the Power Piston to move downward, forcing the
Modulating Plug to open and modulate to maintain constant inlet
pressure. (See pages 3 - 5 for principles of operation of other
A4W Variations.) An increase in inlet pressure lifts the Diaphragm
further, allowing more pressure on top of the Power Piston and
opening the valve wider. A decrease in inlet pressure causes the
Diaphragm to move closer to the Pilot Seat reducing the pressure
on the top of the Power Piston and allowing the Closing Spring to
reduce the valve opening.
The degree of valve opening is controlled by the amount of
pressure on top of the Power Piston, which in turn is controlled by
the fl ow through the Pilot Seat and the bleed off through the bleed
hole in the Power Piston to the outlet of the valve. The volume of
bleed fl ow from the top of the Piston to the valve outlet through
the clearance between the Power Piston and the piston bore is
very small because the Power Piston is fi tted with a Seal Ring.
Manual Opening Stem
All Type A4W Regulators are provided with a Manual Opening
Stem located at the top of the valve (refer to Fig. 1 for the location
of the stem and other related parts). For access to the stem
the Seal Cap on top of the regulator must be removed. Manual
opening is accomplished by turning the stem clockwise until only
the fl ats on the end of the stem protrude from the Packing Nut. To
reset for automatic operation, turn the stem counter-clockwise
as far as it goes.
CAUTIONS: 1.) The Seal Cap must be removed with care, as
refrigerant may have been trapped inside the cap. 2.) BEFORE
turning the stem, the Packing Nut should be loosened slightly,
and 3.) AFTER turning the stem, the Packing Nut should be
retightened. 4.) Always replace the Seal Cap when work with the
regulator is completed.
Adjustment
INLET PRESSURE REGULATORS - A4W - (See Fig. 1) Install an
accurate pressure gauge in the gauge port. Back the Adjusting
Stem all of the way out to stop (counterclockwise). This will
reduce the set-point to its lowest level and will cause the valve to
OPEN wide. Start the system, and when the valve outlet pressure
is approaching the desired inlet pressure, turn the Adjusting
Stem in (clockwise) until the pressure gauge shows a slight
rise in inlet pressure. At this point the Adjusting Stem may be
turned in (clockwise) to raise the pressure further, or backed out
(counterclockwise) to lower it, but the fi nal adjustment should be
made after the system has been operating for a period of time and
has stabilized.
OUTLET PRESSURE REGULATORS - A4WOE - (See Figs. 2,
2A) Install an accurate pressure gauge at the gauge port in the
A4WOE Adapter which is located next to the sensing tube that is
connected to the valve outlet line. Back the Adjusting Stem all of
the way out to stop (counterclockwise). This will reduce the setpoint to its lowest level and cause the valve to CLOSE. Operate the
system until the outlet pressure is lower than desired. Slowly turn
the adjusting stem in (clockwise) until the desired outlet pressure
is reached with the system stabilized.
PRESSURE SETTING RANGES
Inlet ranges available are A, V, and D
*Outlet pressure ranges available are V and D
Set-Point Ranges per Turn of (unless otherwise
Adjusting Screw specifi ed)
A: 0 to 10.3 bar 1.7 bar (25 psi) 2.8 bar (40 psig)
(0 to 150 psig)
*V: 500mm hg to 8.3 bar 1.7 bar (25 psi) 1.0 bar (15 psig)
(20 in hg to 120 psig)
*D: 5.2 to 19.3 bar 3.7 bar (53 psi) 9.7 bar (140 psig)
(75 to 280 psig)
A Vacuum Range Regulator uses a Vacuum Cartridge instead of
the standard Pilot Seat 44. Except for this one difference, a “V”
Range Regulator is the same as an “A” Range Regulator as far
as the Range Spring 49 and Diaphragm Kits are concerned. (See
Figs. 7 and 8)
Approx. Pressure Changes Factory Set Point
Fig. 2
Refrigerating Specialties Division
Fig. 2A - Outlet Pilot
Type A4WE (See Fig. 1)
Description
The Type A4WE is the same as a Type A4W except that the upstream
or remote pressure must be fi eld connected to the valve at the
gauge connection through an external line. (The external line is
not furnished with the regulator.) A Type A4W can be converted
to an A4WE by removing the adaptor from the body; remove the
alignment pin from passage ‘N’; and rotate the Gasket 5 to block
off the internal feed of upstream pressure. Re-assemble. (See
)
Fig. 7
Purpose
The Type A4WE is used when it is advantageous to use an external
source of upstream pressure to the regulator. Whatever the
source of pressure may be, it will be that pressure, as it exists
when it reaches the regulator, that will be controlled. There is a
small fl ow rate of fl uid through the external line and care must be
used to avoid a pressure drop by not under sizing the pipe or using
too long a length. Normally a US 3/8” pipe size not exceeding 6m
(20 ft.) in length will be adequate.
2
The pressure as measured at the connection to the valve must be
no less than the pressure at the valve inlet.
A 13mm (1/2”) Type RSF strainer can be installed in the above line
to protect the critical pilot circuit of the main valve and eliminate
the space required for and the cost of a full line-size strainer.
If this is done, it should be remembered that any pressure drop
in this line caused by an overloaded strainer basket will affect
the actual pressure at which the regulator will control. If this is
the case, then the actual pressure at the main valve inlet will be
higher than it should be by an amount equal to the pressure drop
through the pilot circuit strainer.
Principles of Operation
The operation of the Type A4WE is the same as that described
above for the A4W except that the upstream pressure being
controlled is fed to the valve externally.
Adjustment
Follow the instructions above for the Type A4W Regulator.
Type A4WS (See Fig. 3)
Description
The Type A4WS is an inlet pressure regulator with a pilot electric
shut off. The integrally mounted solenoid must be energized
for the valve to function as a regulator. When de-energized the
regulator is closed regardless of inlet pressure.
Purpose
The Type A4WS should be used where it is required at particular
times to stop all fl ow through the regulator. The valve, however, is
NOT a check valve and cannot prevent reverse fl ow of fl uid if the
outlet pressure exceeds the inlet pressure by more than 0.14 bar
(2.0 psi). Typical uses include defrost applications as well as part
of a temperature control system.
Principles of Operation
The operation of the A4WS is the same as that described for the
A4W on page 2, except the inlet pressure from passage N must
pass through the S6A Pilot Solenoid Valve before it can reach the
diaphragm. Thus, the S6A Pilot Solenoid must be energized before
the A4WS can begin to regulate, regardless of inlet pressure.
Adjustment
With the solenoid pilot electrically energized, proceed as
described above for Inlet Pressure Regulators.
Fig. 3 - A4WS
Type A4WB (See Fig. 4)
Description
The Type A4WB is an Inlet Pressure Regulator with a Pilot Electric
Wide-opening, or Bypass, variation. When the integrally mounted
solenoid is energized the main valve is wide open thereby
bypassing the regulator function, that is, not regulating. However,
in the wide open mode the regulator will still require the 0.14 bar
(2 psi) minimum pressure difference to be fully open. When the
solenoid is de-energized the valve functions as an inlet pressure
regulator.
Purpose
The Type A4WB frequently is used in the wide-open mode when
maximum refrigeration capacity from an evaporator is required.
During the defrost of the evaporator, the regulator pilot solenoid
is de-energized, thus functioning as a defrost relief regulator or
for high pressure limit protection. Also, this regulator can be used
in the wide open mode for evaporator pump out prior to defrost.
When used in a discharge pressure line, it can, when de-energized,
hold back enough pressure for some heat reclaim or defrosting
function and then, when energized, allow the discharge pressure
to decrease to a lower level.
Principles of Operation
The operation of the A4WB is the same as that described for the
A4W on page 2, when operating as a regulator (Pilot Solenoid Deenergized). When the solenoid is energized the upstream pressure
from passage N bypasses the underside of the diaphragm and
is fed directly to the top of the piston, whereby, provided a 0.14
bar (2 psi) pressure difference exists across the main valve, the
Modulating Plug will be held wide open.
Adjustment
With the solenoid pilot electrically de-energized, proceed as
described above for Inlet Pressure Regulators.
Fig. 4 - A4WB
Type A4WD (See Fig. 5)
Description
The Type A4WD is a Dual Inlet Pressure Regulator capable
of regulating two different pressure set-points. When the
integrally mounted S6A Pilot Solenoid is energized, the regulator
is controlling the lower of the two set-points, which must be
adjusted on the pressure pilot over the center of the main valve.
When the solenoid is de-energized, the regulator is controlling
the higher of the two set-points, which must be adjusted on the
bolt-on (outboard) pressure pilot.
Purpose
The Type A4WD uses are similar to those for the A4WB except
that, instead of operating in a wide-open position when the pilot
solenoid is energized, the regulator is controlling at some preset
level.
Typical uses include capacity control of an evaporator at two
different pressure levels to regulate temperature, or evaporator
pressure control combined with defrost or wash down pressure
relief.
Principles of Operation
The operation of the A4WD is similar to that described for the
A4W on page 2. When the Pilot Solenoid is energized, upstream
pressure from passage N is made available to both diaphragms.
Since the path of least resistance will be through the pilot having
the lower set-point (lower range spring force), that pilot will
control.
When the Pilot Solenoid is de-energized, the upstream pressure
from passage N can fl ow only to the high pressure pilot, which will
then control the regulator.
Adjustment
Electrically de-energize the solenoid pilot and adjust the modular
(bolt-on) pressure pilot for the desired high pressure setting
following the adjusting procedure as described above.
Refrigerating Specialties Division
3
Energize the solenoid pilot and adjust the integral pressure pilot
for the desired low pressure setting following the same procedure.
The modular (bolt-on) pilot MUST be adjusted for a set-point
HIGHER than the integral pilot or the regulator will always be
controlling at the lower set-point whether the pilot solenoid is
energized or de-energized.
Fig. 5 - A4WD
Type A4WP
Description
The Type A4WP is an Inlet Pressure Regulator whose setpoint
can be compensated by a remote pressure. Typically the remote
pressure would be a pneumatic signal from a thermostat or
controller, but it can also be a refrigerant pressure. The remote
pressure is fed into the bonnet of the regulator where it is capable
of changing the set-point on a 1:1 basis. That is, a 0.07 bar (1.0
psi) change in the remote pressure will create a 0.07 bar (1.0 psi)
change in the set-point of the regulator.
Although not specifi cally described in this bulletin, the A4WP
is also available with any of the “S”, “B”, “D” and “OE” features
mentioned elsewhere
Purpose
The Type A4WP can be used to vary an evaporator or condenser
pressure to match a changing load condition. A pneumatic
thermostat-controller modulates the air pressure applied to
the top of the diaphragm as the temperature at the thermostat
changes. Whether used as part of a cooling system to control
evaporator pressure, or as part of a Heat Reclaim system to control
condensing pressure, a rise in temperature at the thermostat
must cause a decrease in controlled air pressure. (Normally
this is known as a “Reverse Acting” thermostat-controller.) The
decrease in air pressure will lower the regulator set-point and
produce a lower inlet pressure and lower evaporator or condenser
temperature. Conversely, a drop in temperature at the thermostat
must cause an increase in air pressure, with a resultant increase
in evaporator or condenser temperature. Usually, the controller
modulates the air pressure from 0.21 to 1.0 bar (3 to 15 psig)
throughout its control range.
The A4WP can be used as a Differential Pressure Regulator if the
regulator outlet pressure is connected to the bonnet.
Principles of Operation
The Type A4WP operation is the same as the A4W described above
except that the set-point is changed (compensated) on a 1:1 basis
by the pressure that is fed into the bonnet.
If the A4WP is part of a pneumatically operated control system,
the air must be clean, dry and oil free. To avoid the possibility of
moisture from compressed air freezing in the bonnet or in other
parts of the control system, a dehydrated air system must be used
whenever it may come in contact with sub-freezing temperatures.
This is particularly true if the regulator is controlling suction gas
fl ow at temperatures below freezing.
Adjustment
If the A4WP is part of a pneumatically operated control system.
the controller must be adjusted according to the manufacturers
instructions to obtain the optimum system performance. To
adjust the pressure regulator. disconnect the air line and follow
the instructions, above listed for the Type A4W. This setting
represents the lowest inlet pressure the regulator will allow,
.
thus providing a low limit feature to the regulator. Next, connect
the air line. From this point the regulator’s set-point will be
increased on a 1:1 ratio with the air pressure increase.
If the A4WP is compensated by a remote refrigerant pressure, the
setpoint of the regulator (the inlet pressure it will be controlling)
will be equal to the sum of the remote pressure and the pressure
equivalent to that made by the range spring adjustment. If the
remote pressure is the regulator outlet pressure, then the valve
will control an inlet pressure equal to the outlet pressure plus the
Range Spring setting. Or, said another way, the Regulator will be
a Differential Pressure Regulator because the set-point will be
the difference in pressure across the regulator.
Type A4WOE (See Fig. 2-2,2A)
Description
The Type A4WOE is an Outlet Pressure Regulator with an external,
fi eld installed connection to the downstream (outlet) pipe of the
regulator. This connection is not furnished with the regulator. The
regulator will tend to open on a drop in outlet pressure below
set-point and will tend to close on a rise in outlet pressure above
set-point.
Although not described in this bulletin, the A4WOE is also available
in combination with the “S”, “B”, “D” and “P” features described
elsewhere.
Purpose
The Type A4WOE will modulate fl ow of refrigerant fl uid to
maintain a constant downstream pressure as set-for, despite
fl uctuations in load. However, once closed, the regulator can do
nothing further to reduce downstream pressure. This reduction
must come from system capacity. The regulator cannot maintain
set-for pressure if uncontrolled blanch lines feed into the main
pipeline downstream of the A4WOE Regulator.
Typical applications are as a hold back or crankcase pressure
regulator to prevent pressure rise in a suction main, or to prevent
too low a plant suction pressure by putting an artifi cial load on the
main from a higher pressure source.
Principles of Operation
The outlet pressure is sensed under the Diaphragm through the
external tube which has been installed in the fi eld to the outlet
pipe downstream of the main valve. When the force created by the
outlet pressure acting under the Diaphragm is less than the force
of the Range Spring, the pilot is open, allowing upstream pressure
from passage N to fl ow to the top of the Piston. This causes the
Piston to force the Modulating Plug to open to maintain a constant
outlet pressure. A decrease in the outlet pressure allows the
Range Spring to open the pilot further, allowing more pressure
on top of the piston and opening the Modulating Plug further.
An increase in outlet pressure will lift the Diaphragm against
the force of the Range Spring, allowing the Pilot Plug to start
to close. The pressure on top of the Piston is decreased
and the Closing Spring acts to reduce the opening of the
Modulating Plug and the fl ow of fl uid through the regulator.
Fig. 2-2 - A4WOE
Refrigerating Specialties Division
4
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”.)
Fig. 6 - A4WR
Refrigerating Specialties Division
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
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