Cashco B2 User Manual

INSTALLATION, OPERATION & MAINTENANCE MANUAL (IOM)

IOM-B2

11/13

MODEL B2

BACK PRESSURE REGULATOR

SECTION l

I. DESCRIPTION AND SCOPE

The Model B2 is a back pressure regulator used to control upstream (inlet or P1) pressure. Sizes are 1/4" and
3/8" NPT (DN8 and DN10) FNPT or 1/2" (DN15) with Tri-Clamp connections. The unit is suitable for gaseous or
liquid service. Refer to Technical Bulletin B2-TB for design conditions and selection rec om men da tions.

CAUTION

This is not a safety device and must not be substituted for a code approved pressure safety relief valve or a
rupture disc.

SECTION II

II. INSTALLATION

CAUTION

Installation of adequate overpressure pro tec tion is
recommended to pro tect the reg u la tor from over­ pres sure and all down stream equip ment from dam­ age in the event of regulator failure.

1. An inlet block valve should always be installed.

2. If service application is continuous such that
shut down is not readily accomplished, it is rec­ommended that an inlet block valve, outlet block
valve, and a manual bypass valve be installed.

3. Pipe unions should be installed to allow removal
from piping.

4. An outlet pressure gauge should be located ap­ proxi mately ten pipe diameters downstream, and
within sight.

5. All installations should include a downstream re­ lief de vice if the inlet pressure could exceed the
pres sure rating of any downstream equip ment or
the maximum outlet pressure rating of the unit.

6. Clean the pip ing of all foreign material including
chips, welding scale, oil, grease and dirt before
installing the reg u la tor. Strainers are rec om ­mend ed.

7. In plac ing thread seal ant on pipe ends pri or to
en gage ment, ensure that excess material is re-

moved and not allowed to enter the regulator
upon startup.

8. Flow Direction: Install so the fl ow direction
match es the inlet stamp on the main regulator
body (1).

9. For best performance, install in well drained
hori zon tal pipe.

10. Basic Regulator - (Refer to Figure 2, Model B2):
Regulator may be rotated around the pipe axis
360°. Recommended position is with knob (4)
ver ti cal upwards.

11. Regulators are not to be buried un der ground.

12. For insulated piping systems, recommendation
is to not insulate regulator.

SECTION III

III. PRINCIPLE OF OPERATION

1. Movement occurs as pressure variations register on
the diaphragm. The registering pressure is the inlet,

, or upstream pressure. The range spring opposes

P

1

diaphragm movement. As inlet pressure drops, the
range spring pushes the dia phragm down, closing

SECTION IV

IV. STARTUP

the port; as inlet pres sure in creas es, the diaphragm
pushes up and the port opens.

2. A complete diaphragm failure will cause the reg u la tor
to fail closed.

CAUTION

The maximum outlet pressure is stamped on the
body as the upper range spring pres sure level, and
is the rec om mend ed “upper operative limit” for the
sens ing diaphragm (see Sec tion IV. Startup, Step

7). Higher press ures could dam age the di a phragm.
(Field hydro static tests fre quent ly de stroy di a ­phragms. DO NOT HYDRO STATIC TEST THRU AN
IN STALLED UNIT; ISO LATE FROM TEST.)

1. Start with the block valves closed. A bypass valve may
be used to maintain inlet pressure in the upstream
system without changing the fol low ing steps.

2. Relax the range spring (15) by turning knob (4) counter
clockwise (CCW) a minimum of three (3) full rev o lu­ tions. This reduces the inlet (up stream) pres sure
setpoint.

3. If it is a “hot” piping system, and equipped with a
bypass valve, slowly open the bypass valve to pre­heat the system piping and to allow slow ex pan sion
of the piping. Assure proper steam trap operation if
installed. Closely monitor inlet (up stream) pres sure
via gauge to assure not over-pressurizing. NOTE: If

no bypass valve is in stalled, extra caution should be
used in starting up a cold system; i.e. do everything
slowly.

4. Crack open the inlet (upstream) block valve.

5. Slowly open the outlet (downstream) block valve
ob serv ing the inlet (upstream) pressure gauge. De­ ter mine if the regulator is fl owing. If not, slowly rotate
the regulator adjusting screw CCW until fl ow begins.

6. Continue to slowly open the outlet (downstream)
block valve until fully open.

7. Observing the inlet (upstream) pressure gauge,
ro tate knob (4) clockwise (CW )slowly until the inlet
pres sure begins to rise. Rotate CW until the desired
setpoint is reached.

8. Continue to slowly open the inlet (upstream block
valve. If the inlet (upstream) pressure exceeds the
desired setpoint pressure, rotate knob (4) CCW until
the pres sure decreases.

9. When fl ow is established steady enough that both
the outlet and inlet block valves are fully open, begin
to slowly close the bypass valve, if installed.

10. Develop system fl ow to a level near its expected
normal rate, and reset the regulator setpoint by turn­ ing knob (4) CW to increase inlet pressure, or CCW
to reduce inlet pressure.

11. Using a downstream valve, reduce system fl ow to a
min i mum level and ob serve setpoint. Inlet pres sure
will rise from the setpoint of Step 9. (Ensure this rise
does not exceed the stated upper limit of the range
spring by greater than 50%, i.e. 2-50 psig (.14 - 3.4
Barg) range spring, at maximum fl ow the inlet pres-
sure should not exceed 1.5 x 50 psig (3.4 Barg), or
75 psig (5.2 Barg). If it does, consult factory).

12. Increase fl ow to maximum lev el, if possible. Inlet
(up stream or P
setpoint as necessary at the normal fl ow rate.

) pressure should fall off. Re ad just

1

SECTION V

V. SHUTDOWN

1. On systems with a bypass valve, and where sys tem
pressure is to be main tained as the reg u la tor is shut
down, slowly open the bypass valve while closing the
inlet (up stream) block valve. Fully close the inlet (up­ stream) block valve. (When on bypass, the sys tem
pres sure must be con stant ly observed and man u al ly

reg u lat ed. Close the outlet (down stream) block
valve.

CAUTION

Do not walk away and leave a bypassed regulator
unattended.

IOM-B22

2. If the regulator and system are to both be shut
down, slowly close the inlet (upstream) block

SECTION VI

VI. MAINTENANCE

WARNING

SYSTEM UNDER PRESSURE. Prior to performing
any maintenance, isolate the regulator from the sys­tem and relieve all pressure. Failure to do so could
result in personal injury.

A. General:

1. Maintenance procedures hereinafter are

based upon re mov al of the regulator unit
from the pipeline where in stalled.

valve. Close the outlet (downstream) valve only
if reg u la tor re mov al is required.

Figure 1: Diaphragm Subassembly

spring button (5) should remain inside the
spring cham ber.

2. Owner should refer to owner's procedures for

removal, handling, cleaning and disposal of
non reuseable parts, i.e. gaskets, etc.

3. Refer to Figure 2 for Model B2 basic reg u -

la tor and Figure 1 for the diaphragm sub as ­sem bly.

B. Diaphragm Replacement - Model B2:

CAUTION

To prevent damage to body, use soft jaws when
placing body in a vise. Position so that vise closes
over the fl ats on lower end of body.

1. Securely install the body (1) in a vise with

knob (4) directed upwards.

WARNING

SPRING UNDER COMPRESSION. Prior to removing
spring chamber, relieve range spring compression
by turning the knob CCW until rotation comes to a
complete stop. Failure to do so may result in fl ying
parts that could cause personal injury.

2. Relax range spring (15) by turning knob (4)

CCW until rotation comes to a complete stop.
NOTE: It is not necessary to remove the knob
(4) before removing the spring chamber (6)
from the body (1).

3. Remove spring chamber (6) by grasping the

fl ats and turning CCW. Upon removal, the
range spring (15), range spring clip (16), and

4. Remove diaphragm subassembly (7) con­ sist ing of the actuator nut (7.3), diaphragm
(7.1), ac tu a tor post (7.2), ac tu a tor gasket
(7.4), ac tu a tor o-ring (7.5). Remove di a ­phragm gas ket (10).

5. Remove actuator nut (7.3) and separate all
parts of the diaphragm subassembly (7).

6. Clean body (1) diaphragm fl ange surface
and all re us able parts according to owner's
procedures. Do not scratch di a phragm

gas ket seat ing sur face. NOTE: On reg u-
la tors origi nally sup plied as “oxygen clean”,
Option-M, main tenance must in clude a level
of clean li ness equal to Cash co's clean ing
stan dard #S-1134. On regulators originally
suppled for Sanitary Service, maintenance
must in clude a level of clean li ness equal to
Cash co clean ing stan dard #S-1576. Contact
factory for details.

7. Inspect and replace any necessary parts.

NOTE: Use only parts man u fac tured and
sup plied by Cashco, Inc. for these products.
See Section VIII.

8. Reassemble di a phragm subassembly (7) by
plac ing the actuator gasket (7.4), di a phragm
(7.1), and actuator o-ring (7.5) over the
threads of the actuator post (7.2). Place a
thread sealant com pound on the threads of
the ac tu a tor post (7.2) prior to installing the
actuator nut (7.3). Install ac tu a tor nut (7.3)
and tighten to the fol low ing torque value: ALL
SIZES: 15 Ft-lbs (20 Nm).

9. Place the diaphragm gas
body (1) diaphragm fl ange. Place di a phragm
sub as sem bly on top of the gasket (10).

ket (10) onto the

IOM-B2

3