Cashco MPRV-H User Manual

INSTALLATION, OPERATION & MAINTENANCE MANUAL (IOM)

IOM-MPRV-H

12-13

MODEL MPRV-H

PRESSURE REDUCING REGULATOR

SECTION I

I. DESCRIPTION AND SCOPE

Model MPRV-H is a pressure reducing regulator used to control downstream (outlet or P2) pressure. Available
in bronze construction with brass and stainless steel trim, 3/8" & 1/2"(DN10 & DN15) FNPT connections. Suit­able for liquid and gaseous service. Refer to Tech ni cal Bul le tin MPRV-H-TB for specifi c design conditions and
selection rec om men da tions.

SECTION II

II. INSTALLATION

CAUTION

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.

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
safety 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 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.

8. Flow Direction: Install so the fl ow direction match-
es the arrow cast on the main regulator body.

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

10A. Basic Regulator - Regulator may be rotated

around the pipe axis 360°. Recommended posi­tion is with spring chamber vertical upwards. Ori­ent such that the spring chamber vent hole does
not collect rain wa ter.

10B. Cryogenic Regulator - Option -5 - Recommended

installation is with spring cham ber hanging di­rectly be low the body in a ver ti cal down wards
orientation. Allows water to drain; etc.

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

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 regulator upon
startup.

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 outlet, P2, or downstream pressure. The
range spring opposes di a phragm movement. As

SECTION IV

IV. STARTUP

CAUTION

The maximum outlet pressure is list ed on the name plate
as the upper range spring pres sure level, and is the rec om ­mend ed "upper operative limit" for the sens ing diaphragm
(See Section IV. Startup, Step 7). Higher press ures could
dam age the di a phragm. (Field hydro static tests fre quent ly
de stroy dia phragms. DO NOT HYDRO STATIC TEST THRU
AN IN STALLED UNIT; ISO LATE FROM TEST.)

1. Start with the block valves closed. A by pass valve
may be used to maintain out let pres sure in the
down stream sys tem without changing the fol low­ ing steps.

2. Relax the range spring by turning the adjusting
screw counter clockwise (CCW) a minimum of
three (3) full revolutions. This reduces the outlet
(down stream) pres sure set point.

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. Closely monitor outlet
(down stream) pres sure via gauge to ensure 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 outlet (downstream) block valve.

5. Slowly open the inlet (upstream) block valve ob­ serv ing the outlet (downstream) pressure gauge.

outlet pressure drops, the range spring pushes
the dia phragm down, opening the port; as outlet
pres sure in creas es, the diaphragm pushes up
and the port opening clos es.

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

De ter mine if the regulator is fl owing. If not, slowly
rotate the regulator adjusting screw clockwise
(CW) until fl ow begins.

6. Continue to slowly open the inlet (upstream) block
valve until fully open.

7. Continue to slowly open the outlet (downstream)
block valve, especially when the downstream pip­ ing system isn't pressurized. If the outlet (down­ stream) pressure exceeds the desired pres sure,
close the block valve and go to Step 2, then return
to Step 4.

8. When fl ow is established steady enough that the
outlet (downstream) block valve is fully open,
be gin to slowly close the bypass valve if installed.

9. Develop system fl ow to a level near its expected
normal rate, and reset the regulator set point by
turning the adjusting screw CW to increase outlet
pressure, or CCW to reduce outlet pressure.

10. Reduce system fl ow to a minimum level and
ob serve set point. Outlet pressure will rise from
the set point of Step 9. The maximum rise in
outlet pressure on decreasing fl ow should not
exceed the stated up per limit of the range spring
by greater than 10%; i.e. 20-80 psig (1.38-5.52
Barg) range spring. (Example: at low fl ow the
outlet pressure should not exceed 88 psig (6.07

barg), if it does, con sult factory).CAUTION

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.

2

SECTION V

CAUTION

Do not walk away and leave a bypassed reg u la tor unat­tended.

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

IOM-MPRV-H

SECTION VI

VI. MAINTENANCE

WARNING

SYSTEM UN DER PRES SURE. Prior to performing any
maintenance, isolate the reg u la tor from the system and
relieve all pres sure. 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.

6. Using the "fl ats" on the pusher plate (14)
secure the pusher plate in a soft jawed vice.
Rotate pressure plate nut (7) CCW to loosen
and remove nut, lock washer (8), pressure
plate (10), diaphragm(s) (11) and gasket (13).
(If a composition di a phragm is used there is
no gasket (13)).

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 1 for view of basic unit and
item number listing of parts.

B. Diaphragm Replacement:

1. Secure body cap (15) in a vise with the spring
chamber (2) oriented upwards.

CAUTION

To prevent damage to body cap, use soft jaws when se­curng the body in a vise.

WARNING

SPRING UNDER COMPRESSION. Prior to re mov ing the
spring chamber, relieve spring com pres sion by back ing
out the adjusting screw. Fail ure to so so may result in
fl ying parts that could cause personal injury.

2. Relax range spring (6) by turning adjusting
screw (3) CCW until removed from spring
cham ber (2).

3. Loosen spring chamber (2) by placing wrench
on “fl ats” and rotating CCW.

4. Remove spring chamber, spring button (5),
range spring (6) and diaphragm stop (9).

5. Remove the diaphragm subassembly con­ sist ing of the pressure plate nut (7), lock
wash er (8), pres sure plate (10), diaphragm
(s) (11), gasket (13) and pusher plate (14).

NOTE the quan tity of dia phragms (11) in cor­ po rated in the assembly. De pend ing on out­let pres sure level, multiple metal diaph ragms
may be “stacked”.

IOM-MPRV-H

Diaphragm Sub as sem bly

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

8. Remove diaphragm gasket (12).

9. Clean body (1) and diaphragm fl ange. Do not
scratch diaphragm gasket seating sur face.

NOTE: If regulator was origi nally sup plied
with Option -5, main tenance must in clude a
level of clean li ness equal to Cash co's clean­ ing stan dard #S-1134. Con tact fac to ry for

details.

10. Reassemble diaphragm subassembly by
plac ing gasket (13), diaphragm(s)(11), pres­sure plate (10) and lock washer (8) over the
threaded post. Assure the pressure plate is
placed with curved outer rim down next to
the diaphragm (11) surface. Place a thread
sealant compound on the threads of the plug
post (14) prior to tightening the pusher plate
nut (7) to the fol low ing torque values:

Diaphragm

Metal 60 (6.8)

Composition 15 (1.7)

Torque

In-lbs (N-m)

11. Place dia phragm gas ket (12) into body (1)
re cess. Place di a phragm sub as sem bly on
top of gasket, nut side up.

12. Place diaphragm stop (9) and range
spring (6) over the pres sure plate nut
(7) of the di a phragm sub as sem bly.

13. Apply Christolube or equivalent into de pres­ sion of spring button (5) where ad just ing
screw (3) makes contact. Set spring but ton
(5) on top of range spring (6); en sure spring
button (5) is laying fl at on top of spring.

3