cashco 6987 Owner's manual

II. INSTALLATION
IOM-6987
11-16
MODEL 6987
BACK PRESSURE / RELIEF REGULATOR
SECTION I
I. DESCRIPTION AND SCOPE
The Model 6987 is a back pressure relief regulator used to control upstream (inlet or P1) pressure. Sizes are 1/2" and
3/4" (DN15 and 20). With proper trim utilization, the unit is suitable for air, inert gases, water, fuel oil and chemicals.
The Model 6987 is not normally utilized in steam service. Refer to Technical Bulletin 6987-TB for design conditions
and selection recommendations.
SECTION II
6. Clean the piping of all foreign material including
chips, welding scale, oil, grease and dirt before
installing the valve. Strainers are recommended.
7. In placing thread sealant on pipe ends prior to
engagement, ensure that excess material is
removed and not allowed to enter the valve upon
startup.
8. Flow Direction: Install so the flow direction
matches the arrow cast on the body. The body
has an angle configuration with a side inlet and
bottom outlet.
9. Regulator may be installed in a vertical or
horizontal pipe.
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
approximately ten pipe diameters upstream and
within sight. An outlet pressure gauge is optional.
5. All installations should include an upstream relief
device if the inlet pressure could exceed the
pressure rating of any equipment or the maximum
inlet pressure rating of the unit.
Recommended Piping Schematic for
Back Pressure/Relief Station
INSTALLATION, OPERATION & MAINTENANCE MANUAL (IOM)
CAUTION
This is not a safety device and must not be substituted for a code approved pressure safety relief valve or a rupture disc.
CAUTION
For welded installations, all internal trim parts, seals and
diaphragm(s) must be removed from regulator body prior
to welding into pipeline. The heat of fusion welding will
damagenon-metallicpartsifnotremoved. NOTE:Thisdoes
not apply to units equipped with extended pipe nipples.
CAUTION
Installation of adequate overpressure protection is
recommended to protect the regulator from overpressure
and all downstream equipment from damage in the event
of regulator failure.
ISO Registered Company

IOM-6987
2
SECTION IV
10. Basic Regulator- (See Figure 1): Regulator
may be rotated around the pipe axis 360°.
Recommended positions are with spring chamber
vertical upwards, or horizontal. Orient such that
the spring chamber vent hole does not collect
rainwater or debris.
11. Regulatorsarenottobedirectburiedunderground.
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, P1or upstream pressure. The range
spring opposes diaphragm movement. As
inlet pressure drops, the range spring pushes
IV. STARTUP 7. 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.
8. 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.
9. When flow 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 flow to a level near its expected
normal rate, and reset the regulator setpoint by
turning the adjusting screw CW to increase inlet
pressure, or CCW to reduce inlet pressure.
11. Reduce system flow 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. 50 - 100 psig (3.4 - 6.9
Barg) range spring, at maximum flow the inlet
pressure should not exceed 1.5 x 100 psig (6.9
Barg), or 150 psig (10.3 Barg). If it does, consult
factory.)
12. Increase flow to maximum level if possible. Inlet
(upstream or P1) pressure should fall off. Readjust
setpoint as necessary at the normal flow rate.
1. 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.
2. Relax the range spring by turning the adjusting
screw counterclockwise (CCW) a minimum of
three (3) full revolutions. This reduces the inlet
(upstream) pressure setpoint.
3. 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. Closely monitor inlet
(upstream) pressure, via gauge, to assure 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.
4. Crack open the inlet (upstream) block valve.
5. Slowly open the outlet (downstream) block
valve observing the inlet (upstream) pressure
gauge. Determine if the regulator is flowing. If
not, slowly rotate the regulator adjusting screw
counterclockwise (CCW) until flow begins.
6. Continue to slowly open the outlet (downstream)
block valve until fully open.
the diaphragm down, closing the port; as inlet
pressure increases, the diaphragm pushes up
and the port opens.
2. A complete diaphragm failure may cause the
valve to fail closed.
WARNING
The maximum inlet pressure is equal to 1.5 times the larger
number of the stated range spring on the nameplate, and is
the recommended “upper operative limit” for the sensing
diaphragm. Higher pressures could damage the diaphragm.
(Field hydrostatic tests frequently destroy diaphragms.
DO NOT HYDROSTATIC TEST THROUGH AN INSTALLED
UNIT; ISOLATE FROM TEST.)

IOM-6987 3
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 disposal of
nonreusable parts, i.e. gaskets, etc.
3. Refer to Figure 2 for basic regulator parts.
B. Diaphragm Replacement:
1. For regulators with NPT end connections
only, fabricate the special tool described
in Figure 1. Rotate the No. 10-32 bolt CW
to collapse the piston spring (20). This will
hold the renewal unit (17) in place during
disassembly. For all other end connection
options, proceed with Step 2.
2. Securely install the body (1) in a vise with the
spring chamber (2) directed upwards.
3. Loosen the adjusting screw lock nut (5) and
rotate the adjusting screw (17) CCW until
removed from the spring chamber (2).
SECTION VI
VI. MAINTENANCE 4. Draw or embed a match mark on the body (1)
and spring chamber (2) flanges.
5. If the special tool in Figure 1 is not being used,
the piston spring (20) is always under tension.
Therefore remove all flange bolts (13)
except two located on opposite sides. Turn
remaining two flange bolts (13) CCW using
even increments. The piston spring (20) will
force the body (1) and spring chamber (2) to
separate.
6. Remove spring chamber (2), spring buttons
(4), range spring (6), ball bearing (9),
pressure plate (8), diaphragms (10), and
diaphragm gasket (11).
7. Inspect pressure plate (8) for deformation due
to over-pressurization. If deformed, replace.
8. Clean all parts to be reused according to
owner's procedures. NOTE: On regulators
originally supplied as “special cleaned”,
Option-55, maintenance must include a
level of cleanliness equal to Cashco’s
cleaning standard #S-1134. On regulators
originally supplied as “special cleaned”,
Option-56, maintenance must include a level
of cleanliness equal to Cashco’s cleaning
standard #S-1542. Contact factory for details.
SECTION V
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 removal is required.
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 (upstream) block valve.
(When on bypass, the system pressure must be
constantly observed and manually regulated.
Close the outlet (downstream) block valve.
Figure 1: Special tool for collapsing piston spring (20).
CAUTION
Do not walk away and leave a bypassed regulator
unattended!
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.
WARNING
SPRING UNDER COMPRESSION. Prior to removing flange
bolts, relieve spring compression by backing out the ad-
justing screw. Failure to do so may result in flying parts
that could cause personal injury.

IOM-6987
4
9. If available, collapse the piston spring (20)
using the special tool from Figure 1. If no
special tool is available, proceed to Step 10.
10. Place new diaphragm gasket (11) and
diaphragms (10) onto body (1).
11. Placemulti-purpose, hightemperature grease
into depression of the pressure plate (8) and
spring buttons (4) where the ball bearing (9)
and adjusting screw (3) bears. In the center
of the diaphragms (10), place the pressure
plate (8), ball bearing (9), spring buttons (4),
and range spring (6). Ensure spring buttons
(4) are laying flat.
12. Aligning the matchmarks, place spring
chamber (2) over the above stacked parts.
Install flange bolts (13). Mechanically tighten
flange bolts (13) in a cross pattern that allows
the spring chamber (2) to be pulled down
evenly. Tighten all flange bolts (13) to the
following torque value: All Sizes: 45–50 Ft-
lbs (61–68 Nm).
NOTE: Never replace bolting (13) with
just any bolting if lost. Bolt heads and nuts
are marked with specification identification
markings. Use only proper grades as
replacements.
13. Reinstall adjusting screw (3) with locknut (5).
14. Spray liquid leak detector to test around flange
bolts (13) and body (1) / spring chamber (2)
connection for leakage. Ensure that an inlet
pressure is maintained during this leak test
of at least mid-range spring level; i.e. 50-100
psig (3.4 - 6.9 Barg) range spring, 75 psig
(5.2 Barg) test pressure minimum.
C. Renewal Unit Maintenance:
1. Refer to previous procedures, Section VI.B.
steps 1–7 to remove all parts above the
renewal unit (17).
2. Remove the piston spring button (17.3),
piston (17.1) with piston o-ring (19), and the
piston spring (20).
3. Remove the cylinder (17.2) by turning CCW.
4. Inspect seating surfaces of the piston (17.1)
and cylinder (17.2). If necessary, relap the
seating surface or replace renewal unit (17).
5. Clean all parts to be reused according to
owner's procedures. NOTE: On regulators
originally supplied as “special cleaned”,
Option-55, maintenance must include a
level of cleanliness equal to Cashco’s
cleaning standard #S-1134. On regulators
originally supplied as “special cleaned”,
Option-56, maintenance must include a level
of cleanliness equal to Cashco’s cleaning
standard #S-1542. Contact factory for details.
6. Lubricate the cylinder (17.2) threads lightly
with thread sealant. Install the cylinder
(17.2) into the body (1) and impact until
approximately 100 Ft-lbs (136 Nm) torque
value is reached. This is a metal to metal seal.
7. Install the piston spring (20) into the body
(1) cavity. Place the piston o-ring (19) into
groove of piston (17.1) and install along with
the piston spring button (17.3) into the cylinder
(17.2).
8. Refer to previous procedures, Section VI.B.
steps 8–13 to replace all other parts.
9. Bench test unit for suitable operation. NOTE:
Regulators are not tight shutoff devices. Even
if pressure falls below set point, a regulator
may or may not develop bubble tight shutoff.
10. Spray liquid leak detector to test around flange
bolts (13) and body (1) / spring chamber (2)
connection for leakage. Ensure that an inlet
pressure is maintained during this leak test
of at least mid-range spring level; i.e. 50-100
psig (3.4 - 6.9 Barg) range spring, 75 psig
(5.2 Barg) test pressure minimum.

IOM-6987 5
SECTION VII
VII. TROUBLE SHOOTING GUIDE
Possible Causes Remedies
A. Oversized regulator. A1.
A2.
A3.
A4.
A5.
Check actual flow conditions, resize regulator for minimum and
maximum flow.
Increase flow rate.
Decrease regulator pressure drop; decrease inlet pressure by placing
throttling orifice in inlet piping union.
Install next step higher range spring. Contact factory
Before replacing regulator, contact factory.
B. Inadequate rangeability. B1.
B2.
B3.
Increase flow rate.
Decrease regulator pressure drop.
Install next step higher range spring. Contact factory
C. Worn piston/cylinder; inadequate guiding. C. Replace renewal unit.
1. Erratic Operation; chattering.
Possible Causes Remedies
A. Regulator undersized. A1.
A2.
Confirm by opening bypass valve together with regulator.
Check actual flow conditions, resize regulator; if regulator has
inadequate capacity, replace with larger unit.
B. Plugged renewal unit. B. Remove renewal unit 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).
C. Replace range spring with proper lower range. Contact factory.
D. Too much proportional band (rise). D1.
D2.
Review P.B. (rise) expected.
Contact factory.
E. Restricted diaphragm movement. E. Ensure no moisture in spring chamber at temperatures below freezing.
Ensure no dust or debris entering vent opening. If rainwater or debris
can enter, re-orient spring chamber.
2. Regulator inlet (upstream) pressure too high.
Possible Causes Remedies
A. Normal-life diaphragm failure. A. Replace diaphragms.
B. Abnormal short-life diaphragm failure. B1.
B2.
B3.
B4.
Can be caused by excessive chattering. See No. 1 to remedy chatter.
Can be caused by corrosive action. Consider alternate diaphragm
material.
For composition diaphragms, ensure not subjecting to over-temperature
conditions.
Upstream (inlet) pressure buildup occurring that overstresses
diaphragms.
3. Leakage through the spring chamber vent hole.
Possible Causes Remedies
A. Plugged spring chamber vent. A. Clean vent opening.
B. Plugged piston guides. B. Remove renewal unit and clean.
C. Fluid too viscous C. Heat fluid. Contact factory.
4. Sluggish Operation.

IOM-6987
6
SECTION VIII
NEW REPLACEMENT UNIT:
Contact your local Cashco, Inc., Sales Represen-
tative 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.
–7–
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 reflects revision level for the product).
PARTS "KIT" for FIELD REPAIR:
Contact your local Cashco, Inc., Sales Represen-
tative 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.
NOTE: Those part numbers that have a quantity indicated
under "Spare Parts" in column "A” reflect 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 cross-
sectional drawings included in this manual for part
identification and selection.
A Local Sales Representative will provide quotation
for appropriate Kit Number, 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 ap-
propriate ratings and new product code to accommodate
the recommended part(s) changes.
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 specifications 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-6987 7
Figure 2: Basic Model 6987 - Metal Seat
Range Springs from 50 psig to 200 psig.
ITEM REPAIR PARTS
NO. DESCRIPTION Kit B
1 Body
2 Spring chamber
3 Adjusting Screw
4 Spring Buttons (2)
5 Adjusting Screw Lock Nut
6 Range Spring
7 Diaphragm Ring
(upper range springs only. See Figure 3)
8 Pressure Plate
9 Ball Bearing
10 Diaphragms--------------------------- ‡‡
11 Diaphragm Gasket ------------------ ‡‡
13 Flange Bolts
17 Renewal Unit
17.1 Piston ------------------------------ ‡‡
17.2 Cylinder---------------------------- ‡‡
17.3 Piston Spring Button ----------- ‡‡
19 Piston o-ring -------------------------- ‡‡
20 Piston Spring ------------------------- ‡‡
24 Pipe Plug
7
8
94
17.3
10
19
Figure 3: Basic Model 6987 - Metal Seat
Range Springs from 200 psig to 800 psig.
ITEMS NOT SHOWN
16 Name Plate
‡‡
‡‡
‡‡

IOM-6987 8
ATEX 94/9/EC: Explosive Atmospheres and Cashco Inc. Regulators
These valves satisfy the safety conditions according to EN 13463-1 and EN 13463-5 for equipment group IIG 2 c.
Caution: Because the actual maximum temperature depends not on the equipment itself, but upon the fluid temperature, a
single temperature class or temperature cannot be marked by the manufacturer.
Specific Precaution to Installer: Electrical grounding of valve must occur to minimize risk of effective electrical discharges.
Specific Precaution to Installer: Atmosphere vent holes should be plugged to further minimize the risk of explosion.
Specific Precaution to Maintenance: The Valve Body/ Housing must be regularly cleaned to prevent buildup of dust deposits.
Specific Precaution to Maintenance: Conduct periodic Continuity Check between Valve Body/ Housing and Tank to minimize
risk of electrical discharges.
Attention: When repairing or altering explosion-protected equipment, national regulations must be adhered to. For maintenance
and repairs involving parts, use only manufacturer's original parts.
ATEX requires that all components and equipment be evaluated. Cashco pressure regulators are considered components.
Based on the ATEX Directive, Cashco considers the location where the pressure regulators are installed to be classified
Equipment-group II, Category 3 because flammable gases would only be present for a short period of time in the event of a leak.
It is possible that the location could be classified Equipment-group II, Category 2 if a leak is likely to occur. Please note that the
system owner, not Cashco, is responsible for determining the classification of a particular installation.
Product Assessment
Cashco performed a conformity assessment and risk analysis of its pressure regulator and control valve models and their
common options, with respect to the Essential Health and Safety Requirements in Annex II of the ATEX directive. The details
of the assessment in terms of the individual Essential Health and Safety Requirements, are listed in Table 1. Table 2 lists all of
the models and options that were evaluated and along with their evaluation.
Models and options not listed in Table 2 should be assumed to not have been evaluated and therefore should not be selected
for use in a potentially explosive environment until they have been evaluated.
Standard default options for each listed model were evaluated even if they were not explicitly listed as a separate option in the
table. Not all options listed in the tables are available to all models listed in the tables. Individual TB’s must be referenced for
actual options.
When specifying a regulator that is to be used in a potentially explosive environment one must review the evaluations in Table 1
and 2 for the specific model and each and every option that is being specified, in order to determine the complete assessment
for the unit.
A summary of the models and options found to have an impact on ATEX assessment due to potential ignition sources or other
concerns from the ATEX Essential Health and Safety Requirements, are listed below.
1. The plastic knob used as standard on some models, (P1, P2, P3, P4, P5, P7, 3381, 4381, 1171, and 2171) is a
potential ignition source due to static electricity. To demonstrate otherwise, the knob must be tested to determine
if a transferred charge is below the acceptable values in IEC 60079-0 Section 26.14 (See items 25, 27, and 28 in
Appendix A). Until the plastic knob has been shown to be acceptable, then either the metal knob option, or a preset
outlet pressure option is required to eliminate this ignition source (See items 45 and 64 in Tables).
2. The pressure gauges offered as options on a few of the regulator models (DA’s, P1-7, D, 764, 521), use a plastic
polycarbonate window that is a potential ignition source due to static electricity. To demonstrate that the gauges are
not a potential source of ignition, the gauges would need to be tested to determine if a transferred charge is below
the acceptable values in IEC 60079-0 Section 26.14 or the pressure gauge supplier must provide documentation
NOTICE
Only for Product Codes wherein hazard
category ATEX has been selected.

IOM-6987
9
Cashco, Inc.
P.O. Box 6
Ellsworth, KS 67439-0006
PH [phone]
Fax. # [phone]
www.cashco.com
email: [email protected]
Printed in U.S.A. IOM-6987
Cashco do Brasil, Ltda.
Al.Venus, 340
Indaiatuba - Sao Paulo, Brazil
PH [phone]
Fax. No.
www.cashco.com
email: [email protected]
Cashco GmbH
Handwerkerstrasse 15
15366 Hoppegarten, Germany
PH [phone]
Fax. No. [phone]
www.cashco.com
email: [email protected]
indicating the gauge is compliant with the ATEX Directive (See items 26, 27, and 28 in Appendix A). Until compliance
is determined, regulators should not be ordered with pressure gauges for use in potentially explosive environments.
3. Tied diaphragm regulators with outlet ranges greater than 100 psig should be preset to minimize the risk that improper
operation might lead to an outboard leak and a potentially explosive atmosphere (See item 6 in Table 1).
4. Regulators must be ordered with the non-relieving option (instead of the self-relieving option) if the process gas they are
to be used with is hazardous (flammable, toxic, etc.). The self-relieving option vents process gas through the regulator
cap directly into the atmosphere while the non-relieving option does not. Using regulator with the self- relieving option
in a flammable gas system could create an explosive atmosphere in the vicinity of the regulator.
5. Regulators with customer supplied parts are to be assumed to not have been evaluated with regard to ATEX and thus
are not to be used in a potentially explosive environment unless a documented evaluation for the specific customer
supplied parts in question has been made. Refer to Table 1 for all models and options that have been evaluated.
Product Usage
A summary of ATEX related usage issues that were found in the assessment are listed below.
1. Pressure regulators and control valves must be grounded (earthed) to prevent static charge build-up due to the flowing
media. The regulator can be grounded through any mounting holes on the body with metal to metal contact or the
system piping can be grounded and electrical continuity verified through the body metal seal connections. Grounding
of the regulator should follow the same requirements for the piping system. Also see item 30 in Table 1.
2. The system designer and users must take precautions to prevent rapid system pressurization which may raise surface
temperatures of system components and tubing due to adiabatic compression of the system gas.
3. Heating systems installed by the user could possibly increase the surface temperature and must be evaluated by the
user for compliance with the ATEX Directive. User installation of heating systems applied to the regulator body or
system piping that affects the surface temperature of the pressure regulator is outside the scope of this declaration and
is the responsibility of the user.
4. The Joule-Thomson effect may cause process gases to rise in temperature as they expand going through a regulator.
This could raise the external surface temperature of the regulator body and downstream piping creating a potential
source of ignition. Whether the Joule-Thomson effect leads to heating or cooling of the process gas depends on
the process gas and the inlet and outlet pressures. The system designer is responsible for determining whether the
process gas temperature may rise under any operating conditions. If a process gas temperature rise is possible under
operating conditions, then the system designer must investigate whether the regulator body and downstream piping
may increase in temperature enough to create a potential source of ignition.
The process gas expansion is typically modeled as a constant enthalpy throttling process for determining the temperature change.
A Mollier diagram (Pressure – Enthalpy diagram with constant temperature, density, & entropy contours) or a Temperature –
Entropy diagram with constant enthalpy lines, for the process gas, can be used to determine the temperature change. Helium
and hydrogen are two gases that typically increase in temperature when expanding across a regulator. Other gases may
increase in temperature at sufficiently high pressures.
Product Declaration
If the above issues are addressed by selecting options that do not have potential sources of ignition, avoiding options that
have not been assessed, and by taking the proper usage issue precautions, then Cashco regulators can be considered to be a
mechanical device that does not have its own source of ignition and thus falls outside the scope of the ATEX directive.