Parker A2B Manual

Refrigerating Specialties Division 1
COMPACT
PRESSURE REGULATORS
Type A2B, A2A, A2BK, A2BOE
FOR AMMONIA, R12, R22, R502
AND OTHER COMMON REFRIGERANTS
FEATURES
• Compact Direct Diaphragm Operated
• DesignPressure(MRP):27.6bar(400PSIG)
• Flanged Connections: FPT, SW, WN or ODS
• Available with Close Coupled Strainer
• Stainless Steel Diaphragm
BULLETIN 21-02D
TypeA2B,A2A,A2BK,A2BOE
January 2003
Installation, Service and Parts Information
Description
TheA2Type pressure regulators are compact, direct diaphragm operated,
for use with refrigerant liquid or vapor. The regulators can be used with
ammonia, R12, R-22, R-502, certain other refrigerants, oil and other
approved fluids with similar pressure temperature and corrosion
characteristics. The design pressure (MRP) is 21 bar (300 psig). The
regulators are for use in systems where a small inlet or outlet pressure
regulator is needed.
The regulators are furnished with flanges for FPT: Internal NPT (USA
Standard Taper Pipe Thread), socket weld, weld neck or ODS (solders
over copper tubing of given external diameter) connections. The
regulator can be easily removed for service.
Astrainer can be furnished to close couple to the inlet of the regulator.
Purpose
The A2B, A2BK and A2A are Inlet Pressure Regulators that prevent inlet
(or upstream) pressure from falling below set-point. They will tend to open
onariseininletpressureaboveset-pointandwillbeclosedbelowset-point.
The A2BO and A2BOE are Outlet Pressure Regulators. (The A2BOE
senses outlet pressure through an external connection.) They prevent their
outlet (or downstream) pressure from rising above set-point. They tend to
open on a drop in outlet pressure below set-point and will be closed above
set-point.
Principles of Operation A2B, A2A
The inlet pressure acts on the diaphragm; when the force created by the
pressure exceeds the force of the range spring, the diaphragm is lifted off
of the valve seat and flow occurs between the diaphragm and the valve
seat, from the regulator inlet to the outlet. Increased inlet pressure lifts
the diaphragm further, allowing increased flow. Decrease in inlet pressure
causes the diaphragm to move closer to the valve seat, thus reducing the
flow. Thus, the regulator acts to maintain the inlet pressure approximately
constant. If the inlet pressure drops below the regulator setting, the
diaphragm closes off the flow to keep the inlet pressure from going below
the set point, subject to limits of seat leakage tolerance, or leakage due to
dirt particles on the seat surfaces.
Adjustment A2B, A2A
An accurate pressure gauge should be installed at the gauge connection
on the regulator or in the piping near the regulator inlet.
Carefully remove the seal cap by barely cracking it open to allow any
confined refrigerant to escape gradually. Then turn the adjusting stem in
(clockwise) to raise the set point, or out (counterclockwise) to lower the
set point. Table 1 shows the set point pressure ranges for the regulators.
Do not attempt to exceed the rated maximum pressure setting adjustment
because this could damage the regulator or make it inoperative. Severe
overadjusting could also apply enough force to damage the diaphragm
and valve seat or put the spring in solid position. So, if the maximum
tightening adjustment has been reached, stop and back out the adjusting
stem (counterclockwise) at least one half turn so the range spring can
move.
After adjusting the regulator it is advisable to observe the maintained
pressure while the system is operating normally and to make any minor
adjustments required at that time. Replace the seal cap after the desired
set point is reached.
TABLE 1. INLET PRESSURE SETTING RANGES
APPROX. CHANGE PER TURN
SET POINT RANGES OF ADJUSTING SCREW
A: 0 to 10.3 bar (0 to 150 psig) 1.7 bar (25 psi)
V: 500 mm Hg to 8 bar
(20 in. Hg to 120 psig) 1.7 bar (25 psi)
D: 5 to 19 bar (75 to 280 psig) 3.6 bar (53 psi)
050012 ISO 9001-2000 CERTIFIED

Refrigerating Specialties Division 2
PARTS KITS LIST
Valve Item
Type No. Description Oty. Kit No.
A2B Spring/Stem Kit Ranges A & Y 1 202006
3 Nut, Packing 1
4 Packing, Stem 1
5 Washer, Flat 1
6 Stem, Adjusting 1
12 Plate, Spring, Upper 1
14 Plate, Spring, Lower 1
13 Spring, Range, Comp 1
15 Follower, Diaphragm 1
A2B, A2BO Spring/Stern Kit Range D 1 202007
3 Nut, Packing 1
4 Packing, Stem 1
5 Washer, Flat 1
6 Stem, Adjusting 1
12 Plate, Spring, Upper 1
14 Plate, Spring, Lower 1
13 Spring, Range, Comp 1
15 Follower, Diaphragm 1
A2A Spring/Stem Kit Range A 1 202344
3 Nut, Packing 1
4 Packing, Stem 1
5 Washer, Flat 1
6 Stem, Adjusting 1
12 Plate, Spring, Upper 1
14 Plate, Spring, Lower 1
13 Spring, Range, Comp 1
15A Follower, Diaphragm 1
Valve Item
Type No. Description Oty. Kit No.
A2A Spring/Stem Range D 1 202345
3 Nut, Packing 1
4 Packing, Stem 1
5 Washer, Flat 1
6 Stem, Adjusting 1
12 Plate, Spring, Upper 1
14 Plate, Spring, Lower 1
13 Spring, Range, Comp 1
15A Follower, Diaphragm 1
A2B Bonnet/Spring Kit Ranges A & V 1 202008
Spring/Stem Kit (202006) 1
1 Seal Cap 1
2 Gasket 1
8 Bonnet 1
11 Screw, Hex Hd. 8
16 Gasket 1
A2B, A2BO Bonnet/Spring Kit Range D 1 202009
Spring/Stem Kit (202007) 1
1 Seal Cap 1
2 Gasket 1
8 Bonnet 1
11 Screw, Hex Hd. 8
16 Gasket 1
A2A Bonnet/Spring Kit 1 202359
Spring/Stem Kit (202344) 1
1 Seal Cap 1
2 Gasket 1
8 Bonnet 1
11 Screw, Hex Hd. 8
16 Gasket 1
A2B, A2BO Diaphragm Kit Ranges A & V 1 200770
17 Diaphragm 1
16 Gasket 1
18 Gasket 1
A2A Diaphragm Kit Ranges A & D 1 200771
17 Diaphragm 2
16 Gasket 1
18 Gasket 1
A2B, A2BO Diaphragm Kit Range D 1 200771
17 Diaphragm 2
16 Gasket 1
18 Gasket 1
A2B Seat Kit, Pilot Range A 1 202001
19 Seat, Pilot 1
Diaphragm Kit (200770) 1
A2B2 Seal Kit, Pilot Range A 1 202000
19 Seal Pilot 1
Diaphragm Kit (200770) 1
A2B Seat Kit, Pilot Range V 1 202004
19B Seat, Pilot 1
Diaphragm Kit (200770) 1
A2B Seat Kit, Pilot Range D 1 202003
19 Seat, Pilot 1
Diaphragm Kit (200771) 1
A2B2 Seat Kit, Pilot Range D 1 202002
19 Seat, Pilot 1
Diaphragm Kit (200771) 1
A2A Seat Kit, Pilot Ranges A & D 1 202005
19A Seat, Pilot 1
Diaphragm Kit 1
A2BO Plug Kit, Pilot 1 201394
27 Plug, Seal 1
28 O-Ring 1
A2BO1 Plug Kit, Pilot Ranges V & D 1 200776
25 Plug, Pilot 1
26 O-Ring (A2BO1 E Only) 1
28 O-Ring 1
22 Nut, Retainer 1
18 Gasket 1
23 Spring 1
A2BO2 Plug Kit, Pilot Ranges V & D 1 200777
25 Plug, Pilot 1
26 O-Ring (A2BO2E Only) 1
28 O-Ring 1
22 Nut, Retainer 1
18 Gasket 1
23 Spring 1
A2BO4 Plug Kit, Pilot Ranges V & D 1 200778
25 Pilot Plug 1
26 O-Ring (A2BO4E Only) 1
28 O-Ring 1
22 Nut, Retainer 1
18 Gasket 1
23 Spring 1
A2B,A2A,A2BO Packing Kit, Stem 1 202100
5 Washer, Flat 1
3 Nut, Packing 1
4 Packing, Stem 1
A2B,A2A,A2BO Cap Kit, Seal 1 202110
1 Seal Cap 1
2 Gasket 1
A2B,A2A,A2BO
29 Gaskets, Flange 12 202078

Refrigerating Specialties Division 3
Disassembly and Assembly
Refer to the exploded views (Fig. 2) for the parts discussed in this section.
Before disassembling or assembling an A2 regulator read the information
in this bulletin and Bulletin RSB, Safety Procedures for R/S Refrigeration
Control Valves.
Before a regulator Is removed from the line or disassembled in the line,
make sure that all refrigerant has been removed from the regulator
(including the bonnet where applicable), and the regulator is isolated from
the rest of the system in a safe manner.
All A2 Regulators, General Procedure
Disassembly – Remove Seal Cap 1 and back out theAdjusting Stem 6 to
remove all tension from the Range Spring 13. This is necessary to avoid
possible damage to internal parts of the regulator. Remove Bonnet Screws
11 and disassemble parts 12 through 18 as shown in Fig. 2. Normally
parts 3 through 6 do not require disassembly. Inspect parts for dirt,
corrosion and wear and clean or replace as needed. Gaskets and “O”
rings should be replaced whenever a regulator is re-assembled.
Assembly – When assembling the regulator, lightly oil the gaskets with
refrigerant oil. Do not apply oil to the “O” rings because some oils may
cause slight swelling and diameter increase. This does not affect the
performance of the “O” rings, but it may make the assembly difficult. Make
sure all parts are free of dirt and moisture condensate. Dry the parts if
necessary and oil lightly.
All gaskets and “O” rings must be properly aligned. Arrange the parts as
shown in Fig. 2 making sure that the Diaphragm Follower 15 is properly
located in the Bonnet 8. The diaphragm must be installed with the raised
center portion towards the bonnet. Make sure two diaphragms are used
forA2B andA2BO Range D andA2ARangesAand D. Tighten the Bonnet
Screws 11 gradually and evenly. The screws should be tightened by turning
opposing screws alternately rather than in a circular pattern. The ideal
tightening torque is 1.5 kg-m (11 lbs.-ft.).
After the regulator is assembled and re-installed, check all external joints
for leaks. Adjust the regulator spring to the proper set point by turning the
adjusting stem while observing the proper pressure gauges during system
operation.
A2B and A2A
After above General Procedure for disassembly, inspect the Valve Seat
19 top seating surface for dirt, wear or damage. Remove from valve body
and clean, lap on a flat plate or replace as necessary. Examine the
diaphragm region which contacts the seat surface; look for dirt, heavy
scratches or corrosion. If the diaphragm cannot be easily wiped clean, it
should be replaced.
A2BO and A2BOE
After above General Procedure for disassembly, remove Bottom Cap 27.
Disassemble the Valve Plug 25 and Spring 23 by inserting a screwdriver
in the slot in the bottom of the valve plug and turning the hexagon Spring
Nut 22 with a wrench. Inspect the valve plug and the matching seat surface
in the Valve Body 20 for dirt, corrosion or damage. Clean, lap in place or
replace as needed.Assemble new “O” ring 26 to the valve plug onA2BOE
only (no “O” ring 26 required on A2BO), and carefully insert the assembly
into the valve body. Place Spring 23 in place and tighten the Spring Nut
22 with a wrench while inserting a screwdriver into Valve Plug 25. Replace
Bottom Plug “O” ring 28 and screw bottom cap in place.
A2BP
For this regulator, which has an external connection to the bonnet, check
the parts inside the bonnet for dirt, moisture or corrosion, especially on
the outside diameter of diaphragm follower. If source of dirt, moisture or
corrosion cannot be eliminated, it may be advisable to install and maintain
a filter-drier in the sensing line to the bonnet.
SERVICE POINTERS
SYMPTOM-Regulator does not shut off flow
PROBABLE REASON CORRECTION
Incorrect setting .......................................................... Adjust set point as needed.
See appropriate adjustment
procedure.
Wrong pressure range ............................................... Check pressure range,
change range spring if necessary
Diaphragm or seat dirty, damaged or frozen ............ Clean or replace – clean strainer
Diaphragm follower stuck or damaged ...................... Clean or replace.
Install follower carefully
A2BO plug sticking ..................................................... Check for dirt, corrosion or
damage.
Clean or replace. Check mating bore
and seat in valve body.
A2BO plug and seat eroded due to flash gas ........... Replace as needed. Reduce flash
gas by sub-cooling or by reducing
pressure drop across valve by
providing restriction at valve outlet.
A2BO diaphragm ruptured or badly deformed ......... Replace. Make sure Range “D” has 2
diaphragms.
SYMPTOM – Regulator does not open
Incorrect setting .......................................................... Adjust set point as needed.
See appropriate adjustment
procedure.
Wrong pressure range ............................................... Check pressure range,
change range spring if necessary
Diaphragm follower stuck, damaged or frozen ......... Clean or replace.
Install follower carefully
A2B or A2A diaphragm ruptured or badly deformed Replace. Make sure Range “D” has 2
diaphragms.
A2BO plug sticking ..................................................... Check for dirt, corrosion or
damage.
Clean or replace. Check mating bore
and seat in valve body.
SYMPTOM – Regulator operation erratic
Diaphragm or seat dirty or damaged ........................ Clean or replace – clean strainer
A2BO plug sticking ..................................................... Check for dirt, corrosion or damage.
Clean or replace. Check mating bore
and seat in valve body.
Diaphragm follower has burrs or dirt on outside
diameter ...................................................................... Clean or replace.
Check other system components .............................. Adjust or replace as needed.
SYMPTOM – Presure drop across valve too high
Inlet or outlet restricted .............................................. Check for restriction. Clean strainer.
Valve too small ............................................................ Replace with proper size valve.
Large amount of flash gas in a liquid line ................. Reduce flash gas by subcooling.
Reduce line restriction by increasing
pipe size, particularly at the valve
outlet.
Replace with larger valve.
FLANGE TABLE
ÀFPT FLANGES WELDING FLANGES ÃO.D.S. FLANGES
Fit Pipe Socket Weld Weld Neck Flange Tubing Fitting
Nominal Size Socket I.D. Neck O.D. Package No. O.D. I.D.
Pipe Flange Flange
Size Package Nominal O.D.ÁSocket Weld ÂPackage
Inches No. Inches mm Inches mm Inches min Weld Neck Inches mm Inches mm No.
1/4 200000 1/4 13.25 .560 14.22 .540 13.72 200004 200008
3/8 200001 3/8 16.75 .695 17.65 .675 17.15 200005 200009 1/2 12.70 .502 12.75 200012
1/2 200002 1/2 21.25 .860 21.84 .840 21.34 200006 200010 5/8 15.87 .627 15.92 200013
3/4 200003 3/4 26.75 1.070 27.18 1.050 26.67 200007 200011 7/8 22.22 .877 22.27 200014
ÀFPT – Internal NPT (USA Standard Taper Pipe Thread) ÁMetric steel tubing used for refrigeration
ÂMetric copper tubing used for refrigeration ÃODS Connections to fit copper tubing of given outside diameter
DEFINITIONS: O.D.S. – Outside Diameter Sweat; I.D. – Inside Diameter; O.D. – Outside Diameter
When ordering flanges, use the proper package number from Flange Table. A Flange Package consists of two flanges only.

Refrigerating Specialties Division 4
Principles of Operation A2BO, A2BOE
In the A2BO the outlet pressure is sensed under the diaphragm. As the
outlet pressure decreases below the set point, the range spring pushes
the diaphragm against the valve plug, moving the plug off the seat and
allowing flow through the regulator (Fig. 3).As the outlet pressure increases
it moves the diaphragm against the force of the range spring and allows
the valve plug to move towards its seat, thus reducing the flow through
the valve. When the outlet pressure exceeds the regulator set point, the
regulator is closed.
TheA2BOE externally equalized pressure regulator operates like the A2BO
except the sensing pressure under the diaphragm is from a point
downstream of the valve (Fig. 4).
Adjustment A2BO, A2BOE
Anaccuratepressuregaugeshouldbeinstalledattheoutletoftheregulator
(or at the pressure sensing point for A2BOE). In case of a compensated
pressure regulator, pressure gauges should be installed at the outlet of
the regulator and also at the compensating pressure to the bonnet.
Carefully remove the seal cap and turn the adjusting stem in (clockwise)
to raise the set point, tending to open the seat; or out (counterclockwise)
to lower the set point, tending to close the seat. Table 2 shows the set
point pressure ranges for the regulators. Do not attempt to exceed the
rated maximum pressure setting adjustment because this could damage
the regulator or make it inoperative. Severe over adjusting could also apply
enough force to damage the diaphragm, or put the spring in solid position.
So, if the maximum tightening adjustment has been reached, stop and
back out the adjusting stem (counterclockwise) at least one half turn so
the range spring can move.
After adjusting the regulator, it is advisable to observe the maintained
pressure while the system is operating normally, and to make any minor
adjustments desired at that time. Replace the seal cap after the desired
set point is reached.
TABLE 2. A2BO OUTLET PRESSURE SETTING RANGES
SET POINT RANGES APPROX. CHANGE PER TURN
OF ADJUSTING SCREW
V: 500 mm hg to 8 bar
(20 in. hg to 120 psig) 1.8 bar (25 psi)
D: 5 to 19 bar (75 to 280 psig) 3.6 bar (53 psi)
Installation All A2 Regulators
Do not remove the protective coverings from the inlet and outlet of the
regulator until the regulator is ready to be installed. Protect the inside of
the regulator from moisture, dirt and chips before and during Installation.
When welded or brazed flange connections are used, all slag, scale, and
loose particles should be removed from the flange interior before the
regulator is installed between the flanges.
Tighten flange bolts and nuts evenly to provide proper seating of the flange
gasket and to avoid damage to gasket or flanges. A close coupled
companion strainer is available for installation at the inlet of the regulator
to help to protect it from any foreign material in the system.
The regulator must be installed with the arrow on the valve body pointing
in the direction of the flow for the regulator to function properly. Backwards
flow through the regulator is uncontrolled and will vary with the valve model,
itssettingandthereversepressuredropencountered.The regulator should
be installed in a location where it is easily accessible for adjustment and
maintenance. The location should be such that the regulator can not be
easily damaged by material handling equipment. When it is necessary to
insulate the regulator (and companion strainer), the insulation should be
installed to provide access to the regulator (and companion strainer) for
adjustment and maintenance. Proper indicating pressure gauges should
be installed to be easily visible to the operator adjusting the regulator.
Warranty
All Refrigerating Specialties Products are warranted against defect in
workmanship and materials for a period of one year from date of shipment
from factory. This warranty is in force only when products are properly
installed, maintained and operated in use and service as specifically stated
in Refrigerating Specialties Catalogs or Bulletins for normal refrigeration
applications, unless otherwise approved in writing by Refrigerating
Specialties Division. Defective products, or parts thereof, returned to the
factory with transportation charges prepaid and found to be defective by
factory inspection will be replaced or repaired at Refrigerating Specialties’
option, free of charge, F.O.B. factory. Warranty does not cover products
which have been altered or repaired in the field; damaged in transit, or
have suffered accidents, misuse, or abuse. Products disabled by dirt, or
other foreign substances will not be considered defective.
THE EXPRESS WARRANTY SET FORTH ABOVE CONSTITUTES THE
ONLY WARRANTY APPLICABLE TO REFRIGERATING SPECIALTIES
PRODUCTS, AND IS IN LIEU OF ALL OTHER WARRANTIES,
EXPRESSED OR IMPLIED, WRITTEN OR ORAL, INCLUDING ANY
WARRANTY OR MERCHANTABILITY, OR FITNESS FORAPARTICULAR
PURPOSE. No employee, agent, dealer or other person is authorized to
give any warranties on behalf of Refrigerating Specialties, nor to assume,
for Refrigerating Specialties, any other liability in connection with any of
its products.
Safe Operation
(see also Bulletin RSBCV)
People doing any work on a refrigeration system must be qualified and
completely familiar with the system and the Refrigerating Specialties
Division valves involved, or all other precautions will be meaningless. This
includes reading and understanding pertinent Refrigerating Specialties
Division product Bulletins, and Safety Bulletin RSB prior to installation or
servicing work.
Where cold refrigerant liquid lines are used, it is necessary that certain
precautions be taken to avoid damage which could result from liquid
expansion. Temperature increase in a piping section full of solid liquid will
cause high pressure due to the expanding liquid which can possibly rupture
a gasket, pipe or valve. All hand valves isolating such sections should be
marked, warning against accidental closing, and must not be closed until
the liquid is removed. Check valves must never be installed upstream of
solenoid valves, or regulators with electric shutoff, nor should hand valves
upstream of solenoid valves or downstream of check valves be closed
until the liquid has been removed. It is advisable to properly install relief
devices in any section where liquid expansion could take place.
Avoid all piping or control arrangements which might produce thermal
or pressure shock.
For the protection of people and products, all refrigerant must be
removed from the section to be worked on before a valve, strainer, or
other device is opened or removed.
Flanges with ODS connections are not suitable for ammonia service.
Parker Hannifin Corporation • Refrigerating Specialties Division
2445 South 25th Avenue • Broadview, IL 60155-3891
Telephone [phone] • Fax [phone]