Cashco BQ User Manual

INSTALLATION, OPERATION & MAINTENANCE MANUAL (IOM)

MODEL BQ

BACK PRESSURE / RELIEF REG U LA TOR

SECTION I

I. DESCRIPTION AND SCOPE

The Model BQ is a back pressure relief regulator used to control upstream (inlet or P1) pressure. Side inlet and fl ow-thru
connections are 1/4", 3/8", and 1/2" NPT (DN8, DN10, DN15); outlet (bottom discharge) connection is always 1/2" NPT (DN15).
With proper trim utilization, the unit is suitable for liquid, gaseous, or steam service. Refer to Technical Bulletin BQ-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

CAUTION

For welded installations, all internal trim parts, seals and
diaphragm(s) must be removed from reg u la tor body prior to
welding into pipeline. The heat of fusion welding will dam­ age non-metallic parts if not re moved. NOTE: This does
not apply to units equipped with extended pipe nip ples.

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

IOM-BQ

12-13

1. An inlet block valve should always be installed.

2. If service application is continuous such that shutdown
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 inlet pressure gauge should be located ap prox i mate ly
ten pipe diameters upstream and within sight. An outlet
pressure gauge is optional.

5. All installations should include an upstream relief de vice
if the inlet pressure could exceed the pressure rating of
any equipment or the maximum inlet pres sure rating of
the unit.

WARNING

The maximum inlet pressure is equal to 1.5 times the larger
number of the stated range spring on the name plate, and is
the recommended “upper operative limit” for the sens ing
di a phragm. Higher pressures could damage the di a phragm.
(Field hy dro stat ic tests fre quent ly destroy di a phragms.
DO NOT HY DRO STAT IC TEST THRU AN IN STALLED UNIT;
ISOLATE FROM TEST.)

Recommended piping schematic for Back Pressure Regulator

6. Clean the piping of all foreign material including chips,
welding scale, oil, grease and dirt before installing the
regulator. Strainers are recommended.

7. In placing thread sealant on pipe ends prior to en­ gage ment, ensure that excess material is removed
and not allowed to enter the regulator upon startup.

8. Flow Direction: Install so the fl ow direction matches
the arrow cast on the body. Connect the inlet pressure
to the body side connection(s). Fluid will relieve out of
the bottom connection. The double inlet connections
are for in-line installation (plug one side connection if
in-line installation is not required).

9. Regulator may be installed in a vertical or horizontal
pipe. If it is a steam system, ensure the piping is properly
trapped and vented.

10a. Basic Regulator - (Refer to Figure 1): Regulator may

be rotated around the pipe axis 360°. Recommended
positions are with the spring chamber vertical upwards,
or horizontal. Orient such that the spring chamber vent
hole does not collect rainwater or debris.

10b. Cryogenic Regulator - Option -5 or -36 (Figure 2):

a. Recommended installation is with spring cham ber

hang ing directly below the body in a ver ti cal down­ wards orientation. Allow water to drain; i.e. melting
frost, rain water.

b. Recommend inert purge gas to spring cham ber

through vent hole and out drain hole.

10c. Differential Regulator - Option -1+6 (Refer to Figure 3).

SECTION III

III. PRINCIPLE OF OPERATION

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

or upstream pressure. The range spring opposes

1

di a phragm movement. As inlet pressure drops, the range

SECTION IV

IV. STARTUP

* NOTE: Systems sequencing operations at startup, normal opera-

tion, failure mode(s), and shutdown must assure that the pressure
(P

) on the spring chamber does not exceed the pressure regis-

Load

tering on the wetted side of the diaphragm. Should this "pressure
reversal" occur, particularly to metal diaphragms, the diaphragm
may be permanently damaged and cause improper operation.

P

> P

1

Load

Pressure reversal is normally caused by the inlet pressure
to a regulator being interrupted (automatically or manually).

1. Ensure the proper range spring is indicated to be within
the regulator by inspection of the unit's name plate. Apply
setpoint pressures that are only within the stated range.

2. When stating direction of rotation of the adjustment screw,
the view is with respect to looking down towards the
adjusting screw or its normal location.

3. Start with the block valves closed. A bypass valve may be
used to maintain inlet pressure in the upstream system
without changing the following steps.

4. Remove closing cap, if installed. Relax the range spring
by turning the adjusting screw counterclockwise (CCW)
a minimum of three (3) full revolutions. This reduces the
inlet (upstream) pres sure setpoint.

5. If it is a “hot” piping system, and equipped with a by­pass valve, slowly open the bypass valve to pre-heat
the system piping and to allow slow expansion of the
piping. Ensure proper steam trap operation if installed.
Closely monitor inlet (upstream) pressure, via gauge, to
ensure not over-pressurizing. NOTE: If no bypass valve

is installed, extra caution should be used in starting up
a cold system; i.e. do everything slowly.

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

a. Recommended installation is with the spring cham ber

directed upwards.

b. No corrosive fl uid should be utilized for spring cham-

ber loading.

c. System operation should ensure that loading pres-

sure (P
diaphragm damage may occur if this op er a tion al

) not exceed inlet pressure (P1); in ter nal

LOAD

mode occurs.

11. Regulators are not to be direct buried underground.
For insulated piping systems, recommendation is to
not insulate regulator.

12. Spring Chamber Vent Tap - Option -25: Pipe spring
chamber vent opening to remote location. Orient so as
not to take on rainwater.

spring pushes the diaphragm down, closing the port;
as inlet pressure increases, the di a phragm pushes up
and the port opens.

2. A com plete diaphragm failure will cause the outlet
process fl uid to mix with the loading fl uid.

7. 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 regula-
tor adjusting screw counterclockwise (CCW) until fl ow
begins.

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

9. Observing the inlet (upstream) pressure gauge, rotate
the adjusting screw clockwise (CW) slowly until the inlet
pressure begins to rise. Rotate CW until the desired
setpoint is reached.

10. Continue to slowly open the inlet (upstream) block valve.
If the inlet (upstream) pressure exceeds the desired
setpoint pressure, rotate the adjusting screw (CCW)
until the pressure decreases.

11. 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.

12. Develop system fl ow to a level near its ex pect ed normal
rate, and reset the regulator setpoint by turning the
adjusting screw CW to increase inlet pressure, or CCW
to reduce inlet pressure.

13. Reduce system fl ow to a minimum level and observe
setpoint. Inlet pressure will rise from the setpoint of Step

9. (Ensure that this rise does not exceed the stated upper
limit of the range spring by greater than 50% i.e. 30-80
psig (2.07 - 5.52 Barg) range spring, at maximum fl ow
the inlet pressure should not exceed 1.5 x 80 (5.6 Barg)
or 120 psig (8.3 Barg). If it does, consult factory.)

14. Increase fl ow to maximum level if possible. Inlet (up-
stream or P
as necessary at the normal fl ow rate.

) pressure should rise. Readjust setpoint

1

IOM-BQ2

V. SHUTDOWN

1. On systems with a bypass valve, and where system
pressure is to be maintained as the regulator is shut
down, slowly open the bypass valve while closing the inlet
(upstream) block valve. Fully close the inlet (up stream)
block valve. When on bypass, the system pressure must
be con stant ly ob served and manually regulated. Close
the outlet (down stream) block valve.

CAUTION

SECTION V

CAUTION

Do not walk away and leave a bypassed reg u la tor un at ­tend ed!

2. If the regulator and system are both to be shutdown,
slowly close the inlet (upstream)block valve. Close the
outlet (downstream) valve only if regulator re mov al is
required.

SECTION VI

VI. MAINTENANCE

WARNING

SYSTEM UNDER PRESSURE. Prior to performing any
main te nance, 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 removal of the regulator unit from the pipe­line where installed.

2. Owner should refer to owner’s procedures for
removal, handling, cleaning and dis pos al of non­reuseable parts, i.e. gaskets, etc.

3. Refer to Figure 1 for basic construction, Figure 3 for
differential construction and Figure 2 for cryo gen ic
construction. For a blow-up of the com po si tion seat
trim, see Figure 4.

4. When counter clockwise (CCW) or clock wise (CW)
rotations are indicated, they are with respect to:

3. Draw or embed a match mark between body cast ing
(1) and spring chamber casting (2) along fl anged
area.

4. Remove all fl ange nuts (8) and fl ange bolts (7).

5. Remove spring chamber (2), range spring (11) and
spring button (12).

6. Remove the diaphragm subassembly con sist ing
of the piston cap screw (9), pres sure plate (10),
diaphragm(s) (4), piston (3.1) and piston gasket
(5). NOTE: Refer to the quantity of diaphragm(s)

(4) in cor po rat ed in the bill of ma te ri als listing.
De pend ing on inlet pres sure level, multiple met al
di a phragms may be “stacked”.

a. Spring Chamber - as viewed from above look-

ing down towards the closing cap or its normal
lo ca tion.

b. Body - as viewed looking into the body cavity

with the spring chamber removed.

B. Diaphragm Replacement:

1. Securely install the body (1) in a vise with the spring
chamber (2) directed upwards.

WARNING

SPRING UNDER COMPRESSION. Prior to removing fl ange
bolts, relieve spring compression by backing out the ad­justing screw. Failure to do so may result in fl ying parts
that could cause personal injury.

2. Relax range spring (11) by turning adjusting screw
(13) CCW until removed from spring cham ber (2).

IOM-BQ

Diaphragm Sub as sem bly

7. To disassemble the diaphragm subassembly,
place piston (3.1) in a vise and rotate piston cap
screw (9) CCW. NOTE: Rec om mend using lead

jaws when placing the piston in a vise, so as not
to damage the piston grooves.

8. Separate all parts (3.1, 4, 5, 9 and 10) and clean
piston gasket (5) surface on piston (3.1) if piston is
to be reused. NOTE: No piston gasket (5) utilized

for composition diaphragm.

9. Inspect pressure plate (10) to ensure no de for ­ma tion due to over-pressurization. If de formed,
re place.

10. Remove diaphragm gasket (6) for metal di a phragm.

NOTE: No diaphragm gasket (6) utilized for com-
po si tion diaphragm.

3

11. Clean body (1) and diaphragm fl ange. NOTE: On

regulators originally supplied as “cleaned for ox y­ gen service”, Option -5, -36 or -55, main te nance
must include a level of cleanliness equal to Cashco
cleaning stan dard #S-1134. Con tact fac to ry for
details.

12. Place diaphragm gasket (6) on body (1) fl ange, if
required.

13. Reassemble diaphragm subassembly by plac ing
piston (3.1) in a vise (recommend using lead jaws
with vise). Assemble parts on piston cap screw (9)
as follows: pressure plate (10), diaphragm(s) (4),
and piston gasket (5), if re quired. NOTE 1: Apply

a light coat of gasket sealant to gasket. NOTE 2:
Ensure the pressure plate is placed with curved
outer rim down next to the diaphragm (4) sur face.

14. Apply thread sealant compound to the threads
of the piston cap screw (9) and thread into piston
(3.1). Rotate pistion cap screw (9) CW and tighten
to the following torques.

DIAPHRAGM TYPE TORQUE

Metal 15 ft-lb (20 N-m)

Composition 12 ft-lb (16 N-m)

15. Insert the diaphragm subassembly into the body
(1). Rotate the assembly to ensure that the piston
is not binding in the cylinder. If nec es sary, buff
piston with Scotch-Brite

®

or equivalvent.

16. Place range spring (11) on the pressure plate (10).

17. Place multipurpose, high temperature grease into
depression of spring button (12) where ad just ing
screw bears. Set spring button (12) onto range
spring (11); ensure spring button (12) is laying
fl at.

C. Special Instructions for Diaphragm Re place ment:

1. For the Option -1+6 Differential Con struc tion, re as ­sem ble the diaphragm sub as sem bly in Sub-Sec tion
B. Step 12 as follows: assemble parts on piston
cap screw (9), pressure plate (10), piston gas ket
(5), diaphragm(s) (4), piston gasket (5), and push er
plate (23). Refer back to Step 13 for "NOTES".

2. For metal diaphragm(s) (4) only, install a second
diaphragm gasket (6) on the top side of the di a­ phragm. NOTE: Clean the di a phragm fl ange area of

the spring chamber (2) thor ough ly be fore assembly.

3. Utilize a new lock nut seal (22) when installing the
adjusting screw (13) and lock nut (14).

4. Install new closing cap gasket (21), re in stall clos ing
cap (20).

D. Trim Replacement:

1. Trim removal requires that diaphragm sub as

sem bly
be removed. Refer to previous pro ce dure Sec tion
VI.B.

2. Using a deep socket with a 24 inch (600mm) le­ver length, place the socket over the cylinder (3.2)
hex sur fac es. Rotate CCW to re move the cylinder
(3.2).

3. Inspect inside surface of cylinder (3.2) at three
points:
a. Seat ring for erosion/wear on seating sur-

fac es.

b. At metal-to-metal surface between body and

cylinder (3.2). If wear exists here, consult fac­tory.

c. Where the piston (3.1) ribbed guides bear

(guide zone).

18. Aligning the matchmarks, place spring cham ber
(2) over the above stacked parts. Install all bolts
(7) and nuts (8) by hand tight en ing. Me chan i cal ly
tighten bolting (7) (8) in a cross pattern that allows
spring chamber (2) to be pulled down even ly. Rec­ om mend ed torques are as follows:

REGULATOR SIZE BOLT SIZE METAL DIAPHRAGM COMP. DIAPHRAGM

ALL 5/16" 15 ft-lb (20 N-m) 12 ft-lb (16 N-m)

NOTE: Never replace bolting (7)(8) with just any
bolting, if lost. Bolt heads and nuts are marked
with specifi cation identifi cation numbers. Use only
prop er grades as replacements.

19. Reinstall adjusting screw (13) with locknut (14).

20. Soap solution test around bolting (7) (8),body (1)
and spring chamber (2) fl anges for leak age. Ensure
that an inlet pressure is maintained during this leak
test of at least mid-range spring level; i.e. 20-75
psig range spring, 50 psig test pres sure minimum.

If wear is signifi cant at any of these points, replace
the piston/cylinder assembly (3).

4. Clean the body (1) cavity. Clean all parts to be
reused. NOTE: On regulators originally sup plied

with Option -55, “special cleaned”, main te nance
must include a level of cleanliness equal to Cashco
Specifi cation #S-1134. Contact factory for de-
tails.

5. Use special care cleaning the fl at mating sur fac es
of the body (1) and cylinder (3.2) shoulder, as this
pressurized joint is metal-to-metal with out a gas­ ket.

6. Lubricate the cylinder (3.2) threads lightly with
thread sealant, insert the cylinder (3.2) into the
body (1) and screw CW until tightly seated. Re­ in stall diaphragm subassembly per Section VI.B.,
Diaphragm Re place ment.

IOM-BQ4

7. Bench test unit for suitable operation. NOTE:
Reg u la tors are not tight shutoff devices. Even if
pressure falls below setpoint, regulator may or may
not develop bubble tight shutoff. In general, tighter
shutoff can be expected with a composition seat.

8. Soap solution test around body (1) fl ange for leak-
age. Test pressure should be the maximum al lowed
by the range spring at the inlet.

SECTION VII

VII. TROUBLE SHOOTING GUIDE

1. Erratic Operation; chattering

Possible Causes Remedies

A. Oversized regulator; inadequate rangeability. A1.

B. Worn piston/cylinder; inadequate guiding. B1. Replace trim.

2. Regulator inlet (upstream) pressure too high:

Possible Causes Remedies

A. Regulator undersized. A1.

B. Plugged trim. B. Remove trim and check for plugged holes in cylinder.

C. Incorrect range spring (screwing out CCW of adjusting

screw does not allow bringing pressure level to a stable
and proper level).

D. Too much build (rise). D1.

E. Restricted diaphragm movement. E. Ensure no moisture in spring chamber at temperatures

Check actual fl ow conditions, resize regulator for mini-
mum and maximum fl ow.
Tighten fl ange bolting.

A2.

Increase fl ow rate.case and washer. Install new thread

A3.

Decrease regulator pressure drop; decrease inlet pres­sure by placing a throttling orifi ce in inlet piping union.

A4.

Install next step higher range spring.

A5.

Before replacing regulator, contact factory.

Confi rm by opening bypass valve together with regulator.

A2.

Check actual fl ow conditions, resize regulator; if regulator
has inadequate capacity, replace with larger unit.

C. Replace range spring with proper lower range.

Review rise (build) expected.

D2.

Contact factory.

D3.

If -1+6 differential, ensure that pressure reversal has not
permanently deformed the metal diaphragm.

below freeze point. Ensure no dust or debris entering
vent opening. If rainwater or debris can enter, reorient
spring chamber.

3. Leakage through the spring chamber vent hole.

Possible Causes Remedies

A. Normal-life diaphragm failure. A. Replace diaphragm.

B. Abnormal short-life diaphragm failure. B1.

4. Sluggish operation.

Possible Causes Remedies

A. Plugged spring chamber vent. A. Clean vent opening.

B. Fluid too viscous. B. Heat fl uid. Contact factory.

IOM-BQ

Can be caused by excessive chattering. See No. 1 to
remedy chatter.

B2.

Can be caused by corrosive action. Consider alternate
diaphragm material.

B3.

Upstream (inlet) pressure buildup occurring that over­stresses diaphragms. Relocate regulator or protect with
safety relief valve.

5

SECTION VIII

VIII. ORDERING INFORMATION:
NEW REPLACEMENT UNIT vs PARTS "KIT" FOR FIELD REPAIR

To obtain a quotation or place an order, please retrieve the Serial Number and Product Code that was stamped
on the metal name plate and attached to the unit. This information can also be found on the Bill of Material
("BOM"). a parts list that was provided when unit was originally shipped. (Serial Number typically 6 digits).
Product Code typical format as follows: (last digit is alpha character that refl ects revision level for the product).

–

NEW REPLACEMENT UNIT:

Contact your local Cashco, Inc., Sales Rep re sen­ ta tive with the Serial Number and Product code.
With this information they can provide a quotation
for a new unit including a complete description,
price and availability.

CAUTION

Do not attempt to alter the original construction of any
unit without assistance and approval from the factory. All
purposed changes will require a new name plate with ap­propriate ratings and new product code to accommodate
the recommended part(s) changes.

PARTS "KIT" for FIELD REPAIR:

Contact your local Cashco, Inc., Sales Rep re sen­ ta tive with the Serial Number and Product code.
Identify the parts and the quantity required to repair
the unit from the "BOM" sheet that was provided
when unit was originally shipped.

–

7

NOTE: Those part numbers that have a quantity indicated

under "Spare Parts" in column "A” refl ect minimum
parts required for inspection and rebuild, - "Soft
Goods Kit". Those in column “B” include minimum
trim replacement parts needed plus those "Soft
Goods" parts from column "A".

If the "BOM" is not available, refer to the cross­sectional drawings included in this manual for part
identifi cation and selection.

A Local Sales Representative will provide quotation
for appropriate Kit Number, Price and Availability.

The contents of this publication are presented for informational purposes only, and while every effort has been made to ensure their accuracy, they are not to be
construed as warranties or guarantees, express or implied, regarding the products or services described herein or their use or applicability. We reserve the right to
modify or improve the designs or specifi cations of such product at any time without notice.
Cashco, Inc. does not assume responsibility for the selection, use or maintenance of any product. Responsibility for proper selection, use and maintenance of any
Cashco, Inc. product remains solely with the purchaser.

IOM-BQ6

Figure 1: Standard Model BQ,

Metal Seat Design

Figure 2: Option -5 or -36 Cryogenic,

Metal Seat De sign

(NOTE: Mount in Horizontal line with
Adjusting Screw down as shown.)

IOM-BQ

Figure 3: Option -1+6 Differential,

Metal Seat Design (includes

Option -1 Clos ing Cap)

Figure 4:

Composition Seat

Item No. Description

1 Body

2 Spring Chamber
3 Trim (Cylinder/Piston/Seat)

3.1 Piston

3.2 Cylinder
4 Diaphragm
5 Piston Gasket
6 Diaphragm Gasket
7 Hex. head Cap Screw (Flange Bolting)
8 Nut (Flange Bolting)
9 Piston Cap Screw
10 Pressure Plate
11 Range Spring
12 Spring Button
13 Adjusting Screw
14 Adjusting Screw Lock Nut
15 Nameplate
20 Closing Cap
21 Closing Cap Gasket
22 Lock Nut Seal
23 Differential Pusher Plate

7

Cashco, Inc.
P.O. Box 6
Ellsworth, KS 67439-0006
PH [phone]
Fax. # [phone]
www.cashco.com
email: [e-mail]

Printed in U.S.A. IOM-BQ

Cashco GmbH
Handwerkerstrasse 15
15366 Hoppegarten, Germany
PH [phone]
Fax. No. [phone]
www.cashco.com
Email: [e-mail]

Cashco do Brasil, Ltda.
Al.Venus, 340
Indaiatuba - Sao Paulo, Brazil
PH [phone]
Fax. No.
www.cashco.com
Email: [e-mail]