Milton Roy MILROYAL G Instruction Manual

MILROYAL® G Pump

Instruction Manual

Manual No : 53942
Rev. : 01
Rev. Date

: 05/2019

PRECAUTIONS

The following precautions should be taken when working with metering pumps.
Please read this section carefully prior to installation.

Protective Clothing

ALWAYS wear protective clothing, face shield, safety glasses and gloves when working on or
near your metering pump. Additional precautions should be taken depending on the solution
being pumped. Refer to Safety Data Sheets for the solution being pumped.

Hearing Protection

It is recommended that hearing protection be used if the pump is in an environment where the
time- weighted average sound level (TWA) of 85 decibels is exceeded (as measured on the A
scale- slow response).

Electrical Safety

• Remove power and ensure that it remains off while maintaining pump.

• DO NOT FORGET TO CONNECT THE PUMP TO EARTH/ GROUND.

• Electric protection of the motor (Thermal protection or by means of fuses) is to correspond

to the rated current indicated on the motor data plate.

Liquid Compatibility

Verify if the materials of construction of the wetted components of your pump are
recommended for the solution (chemical) to be pumped.

Pumps Water “Primed”

All pumps are tested with water at the factory. If your process solution is not compatible with
water, ush the Pump Head Assembly with an appropriate solution before introducing the
process solution.

Plumbing and Electrical Connections

Always adhere to your local plumbing and electrical codes.

Line Depressurization

To reduce the risk of chemical contact during disassembly or maintenance, the suction and
discharge lines should be depressurized before servicing.

Over Pressure Protection

To ensure safe operation of the system it is recommended that some type of safety/pressure­relief valve be installed to protect the piping and other system components from damage due
to over- pressure.

Lifting

This manual should be used as a guide only- Follow your company’s recommended lifting
procedures. It is not intended to replace or take precedence over recommendations, policies
and procedures judged as safe due to the local environment than what is contained herein.
Use lifting equipment that is rated for the weight of the equipment to be lifted.

i Instruction Manual

TABLE OF CONTENTS

SECTION 1 - DESCRIPTION................................................................. 1

1.1 GENERAL ...................................................................... 1

1.2 PRINCIPLES OF OPERATION ...................................................... 1

1.3 GENERAL SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

1.4 PRODUCT CODE ................................................................ 4

SECTION 2 - INSTALLATION ................................................................ 5

2.1 UNPACKING ....................................................................5

2.2 SAFETY PRECAUTIONS .......................................................... 5

2.3 STORAGE ......................................................................5

2.3.1 Temporary Storage .............................................................. 5

2.3.2 Long Term Storage ..............................................................5

2.3.3 Pump Drive.................................................................... 5

2.3.4 Electrical Equipment............................................................. 6

2.4 MOUNTING ..................................................................... 6

2.5 CONVERSION PROCEDURE.......................................................6

2.6 PIPING CONNECTIONS........................................................... 6

2.6.1 NPSH Considerations............................................................ 6

2.6.2 General Piping Considerations..................................................... 7

2.6.3 Suction Piping Considerations .....................................................7

2.6.4 Discharge Piping Considerations ...................................................8

2.6.5 Back Pressure Valves ............................................................8

2.6.6 Pulsation Dampeners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

2.6.7 Safety Valves .................................................................. 9

2.6.8 Check Valves .................................................................. 9

2.6.9 Shut- OFF Valves ............................................................... 9

2.7 ELECTRICAL CONNECTIONS...................................................... 9

SECTION 3 - OPERATION ................................................................. 10

3.1 INITIAL START-UP............................................................... 10

3.1.1 Start- Up for New Pump ......................................................... 10

3.1.2 Start- Up of Pump Containing No Oil in Casing and Displacement Chamber................. 11

3.2 REFILL VALVE ADJUSTMENT ..................................................... 12

3.2.1 Relief Valve Adjustment (With an Adjustable System Back Pressure Valve). ................. 12

3.2.2 Relief Valve Adjustment (Without an Adjustable System Back Pressure Valve). ............... 13

3.3 USE OF AIR PURGE BUTTON ..................................................... 13

3.4 MANUAL CAPACITY CONTROL .................................................... 14

3.5 FILLING PUMPING SYSTEM ...................................................... 14

3.6 CAPACITY CALIBRATION ......................................................... 14

ii Instruction Manual

SECTION 4 - MAINTENANCE............................................................... 15

4.1 RECOMMENDED SPARE PARTS .................................................. 15

4.2 SHIPPING PUMPS FOR REPAIR .................................................. 15

4.3 ROUTINE PREVENTIVE MAINTENANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

4.3.1 Oil Replacement ............................................................... 15

4.3.2 Check Valves ................................................................. 16

4.3.3 Cleaning Fouled Check Valves .................................................... 16

4.3.4 Check Valve Replacement ....................................................... 16

4.3.5 Oil Strainer Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

4.4 CORRECTIVE MAINTENANCE .................................................... 21

4.4.1 3- Function Hydraulic Valve.......................................................21

4.4.2 “MARS” Valve Assembly ......................................................... 21

4.4.3 Rell Valve Assembly ...........................................................22

4.4.4 Diaphragm Replacement ........................................................22

4.4.5 Removal of Pump Liquid End .....................................................23

SECTION 5 - TROUBLESHOOTING .......................................................... 24

5.1 SYMPTOMS & REMEDIES ........................................................24

SECTION 6 - PART NUMBERS.............................................................. 26

6.1 BASIC PARTS LIST- PUMP DRIVE .................................................. 26

6.2 BASIC PARTS LIST- LIQUID END................................................... 28

6.2.1 Mars Valve ................................................................... 28

6.2.2 Rell Valve ................................................................... 28

6.2.3 3- Function Valve ..............................................................29

6.2.4 Check Valve Parts.............................................................. 29

6.2.5 PVC Liquid End ...............................................................30

6.2.6 Metallic Liquid End .............................................................31

6.3 REMAINING LIQUID END PARTS ..................................................33

LIST OF ILLUSTRATIONS

FIGURE 1. Model/Product Code ............................................................... 4

FIGURE 2. Sample Nameplate............................................................... 34

FIGURE 3. Mounting Hole Dimensions. ........................................................34

FIGURE 4. Typical Recommended Pump Installation Scheme ...................................... 34

FIGURE 5. Pump Drive Parts- Side View ....................................................... 35

FIGURE 6. Pump Drive Parts- Top View........................................................ 36

FIGURE 7. Liquid End- Top View.............................................................. 37

FIGURE 8. Liquid End- Cutaway View ......................................................... 38

FIGURE 9. Mars Value .....................................................................39

FIGURE 10. Double- Ball Check Valve Parts (1-1/4”-plastic;1-3/4, 2-1/2”-PVC & metallic) .................. 40

FIGURE 11. Plastic Single- Ball Check Valve Parts: 1-3/4, 2-1/2, & 3” Plungers.......................... 40

FIGURE 12. Plastic Check Valves for 1-1/4” Plunger .............................................. 41

FIGURE 13. Metallic Check Valves for 1-1/4” Plunger.............................................. 42

FIGURE 14. PVC 4- Function Bleed Valve for 1-1/4” Plunger ........................................ 43

iii Instruction Manual

SECTION 1 - DESCRIPTION

1.1 GENERAL

MILROYAL® G pumps are reciprocating, chemical
dosing pumps capable of producing controlled

ows up to 130 gallons per hour (492 L/H) at
pressures up to 600 psi (41 BAR) (depending on
the model). These pumps feature the robust High
Performance Diaphragm (HPD) liquid end, which

eliminates the need for contour plates, and a
non-lost motion stroke adjustment mechanism
based on the variable eccentric principle. This non­lost motion design substantially reduces pressure

and ow pulsations which in turn increases the

life of system components and results in a more
continuous chemical injection. It is designed
for industrial service and offers an accuracy of

±1% of 100% rated ow between 10% and 100%
of its ow range.

The High Performance Diaphragm (HPD) liquid end

combines all of the best characteristics of traditional
liquid ends into one technologically advanced
design. Its operating characteristics and simplicity
of operation make it the best liquid end to consider

rst for most metering pump applications.

Milton Roy’s HPD liquid end overcomes the
net positive suction head (NPSH) restrictions

associated with conventional disc diaphragm
metering pumps. This is accomplished by a unique

mechanically actuated rell system (MARS) that

eliminates the need for diaphragm support plates

thereby lowering pump NPSH requirements.

The MARS also does away with the need for eld
adjustment of the rell mechanism by automatically
compensating for process liquid modications.

This, combined with removable check valves,

makes the HPD an ideal choice for any process in

which downtime is critical.

The HPD features a preformed, PTFE faced

elastomer diaphragm that is compatible with a
wide range of process liquids and chemicals.
The convoluted design of this composite diaphragm

also offers extended life over conventional at disk

designs.

The HPD liquid end is particularly suitable for

pumping costly, aggressive or hazardous liquids
without leakage.

1.2 PRINCIPLE OF OPERATION
(Refer to Figure 5 Through 10)

The pump consists of two major assemblies;
the drive and the liquid end. Pump delivery is a
function of the drive’s stroke rate (strokes/minute),

plunger size and stroke length (% Capacity).

Stroke length can be adjusted while the pump is
running or stopped by turning the stroke adjustment

knob (330).

The drive motor transmits rotary motion to a

worm gear speed reduction unit (343, 50) which
in turn drives the variable eccentric crank (100).

The adjustable crank imparts reciprocating
motion to the plunger/connecting rod assembly

(60, 520, 525). The stroke length is adjusted by

changing the position of the variable eccentric
crank in the connecting rod assembly.

1Instruction Manual

SECTION 1 - DESCRIPTION

The mechanical drive system of the pump drives

the plunger back and forth in the High Performance
Diaphragm (HPD) liquid end supplied with the

pump. At the start of a suction stroke, the plunger
moves away from the liquid end, drawing hydraulic

uid with it. As the hydraulic uid is drawn back,
the exible diaphragm (510) follows, lowering the
pressure of the process uid in the liquid end.

This pressure drop causes the ball(s) in the suction
check valve (Figure 10) to be lifted up thereby

allowing process uid to pass through the suction
line into the diaphragm head (1020). At the same

time, the pressure drop in the diaphragm head
causes the ball(s) in the discharge check valve

(Figure 10) to be pulled closed, blocking ow back

through the discharge line.

Note:

It is important that the pressure in the liquid
end remain above the vapor pressure of the

process uid during the suction stroke. If the
uid pressure drops below the vapor pressure,
cavitation will occur, negatively impacting the
performance of the pump. If you suspect the
possibility of cavitation, contact your Milton Roy
Representative for assistance.

At the end of the suction stroke, the process
reverses, beginning the discharge stroke.
Now the plunger moves forward, pushing hydraulic

uid before it. The hydraulic oil must therefore press
against the diaphragm, exing it forward and raising
the pressure of the process uid in the liquid end.
This pressure increase causes the process uid
to ow outward, forcing the discharge ball check

open and the suction ball check to seat, blocking

back ow through the suction line. The process
uid ows out of the diaphragm head and into the

discharge line. This suction/discharge action is
repeated with every stroke of the pump plunger,
and is the direct cause of the pumping action.

As the pump operates, a small quantity of hydraulic
oil is continuously bled through the air bleed system
(970, 960, 980 in Figure 8) in the three- function
hydraulic valve (air bleed/relief/purge- Figure 8).
An additional small quantity of hydraulic oil is
also lost on every stroke through the clearance
between the plunger and displacement chamber
bore. After a while, these normal losses result in
a shortage of hydraulic oil in the displacement
chamber. When this happens, the diaphragm will
be pulled back tight against the back contoured
surface of the displacement chamber, and part of
the diaphragm will press against the Mechanically
Actuated Rell System (MARS) valve (Figure 9).
Now, when the plunger draws back, a vacuum is
created in the displacement chamber. These two
factors (diaphragm pressing against MARS valve &
vacuum in the displacement chamber) must occur
together to trigger the MARS valve.

When both of these conditions are met, the MARS
valve is forced to its rearward position, and the

poppet (760) opens, allowing hydraulic oil from

the reservoir to enter through the refill valve
(740 in Figure 8) and replenish the lost oil. In this
manner, proper hydraulic balance is constantly
maintained in the displacement chamber.

2

Instruction Manual

SECTION 1 - DESCRIPTION

1.3 GENERAL SPECIFICATIONS

Maximum Capacity Range 20 GPH (76 LPH) to 130 GPH (492 LPH)

Maximum Pressure Range 100 PSIG (7 Bar) to 600 PSIG (41 BAR)

Liquid End Design

Drive Design Non-Lost Motion Variable Eccentric Type.

Plunger Diameters 1-1/4”(32mm), 1-3/4”(45mm), 2-1/2”(63mm), 3”(75mm)

Liquid End Materials of
Construction

Steady State Accuracy ±1% of 100% rated ow between 10% and 100% of rated ow

Capacity Adjustment

Temperature Limits

Suction Pressure Limits

Lubrication Oil bath drive lubrication.

Paint Two part epoxy, yellow RAL 1018

Hydraulically Actuated Diaphragm with Mechanically Actuated Rell

System (MARS).

PVC, 316 SS, Alloy 20.

Micrometer (Standard): Lockable micrometer is adjustable from

0% to 100% while pump is running or stopped

Electronic (Optional): Electronic stroke length adjustment from
4-20ma input.

Ambient Limit:

Note: Limited by standard lubricants. Modications are available through
Applications Engineering.

Plastic Liquid Ends: 20ºF to 140ºF

Metallic Liquid Ends: 20ºF to 190ºF

Minimum Internal Pressure: 3 psia (11.5 psi maximum vacuum)

Maximum Suction Pressure: 100 psig at 80ºF and below.

130ºF Maximum

0ºF Minimum

Liquid Temperature Limits:

3Instruction Manual

SECTION 1 - DESCRIPTION

1.4 PRODUCT CODE

MILROYAL® G pumps are available in a variety of different congurations. The complete product code

is composed of the pump “model number” + “product code”. For a breakdown of the options included
in a specic pump, compare the pump model number and product code found on the pump nameplate

with the model/product code breakdown shown in Figure 1. A sample nameplate is shown in Figure 2.

MODEL NUMBER

MGH

4 5 6

Digit 4 & 5: Plunger Size Digit 6: Liquid End Material

Description

1-1/4”(32mm)

1-3/4”(45mm)

2-1/2”(63mm)

3”(75mm)

PRODUCT CODE

7 8 9 10 11 12 13 14 15 16 17 18 19 20

Code Description Code

20

28

40

48

316 SS

Plastic (PVC)

Alloy 20

PVDF

1

2

5

7

Digit 7 & 8: Stroking Speed

Description

173 spm 10 No motor, Flange Mount, NEMA 56C CB

120 spm 14 No motor, Flange Mount, NEMA 145TC CC

86 spm 20 No motor, Flange Mount, NEMA 182TC CD
43 spm 30 No motor, Flange Mount, IEC80, F165 Flange MD

*Note: SPM’s for 60 Hz, 1725 rpm motor

Code

Digits 9 & 10: Motor

Description Code

Digits 11 & 12: Capacity Adjustment Connection Digit 13 & 14: Check Valve

Description Code Description Code

Manual, Plastic micrometer knob Electronic(4-20 ma input) M2 Pipe- NPT SE

NEMA 4, 115V E1 Pipe- BSP SN
NEMA 4, 230V E2 Pipe- DN (Socket Weld) SQ
Explosion Proof, 115V EA
Explosion Proof, 230V EB
Electronic 4-20 ma input, 24 VDC EG

Digit 15 & 16: Base Diaphragm Digits 17 & 18: Rupture Detection/Double

Description Code Description Code

No Base (Standard) NN No Rupture Detection, Single Diaphragm (Standard) NN
No Base (Optional) 11 No Rupture Detection, Double Diaphragm (Optional) DD

Rupture Detection (Gauge), Double Diaphragm (Optional) C5

Rupture Detection (Gauge + NEMA 4 Pressure Switch),

DD (Opt.)

Rupture Detection (Gauge + Exp Pr Switch), DD (Optional) SE

Digit 19 & 20: Check Valve Type

Description Code

Single Ball 11
Double Ball 22

Note: Degassing options are available. Consult
MRC factory or representative for details

SN

Figure 1. Model/Product Code

4

Instruction Manual

SECTION 2 - INSTALLATION

2.1 UNPACKING

Pumps are shipped Free on Board (FOB) factory

or representative warehouse and the title passes to
the customer when the carrier signs for receipt of
the pump. In the event that damages occur during
shipment, it is the responsibility of the customer to

notify the carrier immediately and to le a damage

claim.

Carefully examine the shipping crate upon receipt

from the carrier to be sure there is no obvious
damage to the contents. Open the crate carefully so
accessory items fastened to the inside of the crate

will not be damaged or lost. Examine all material

inside the crate and check against packing list to
be sure that all items are accounted for and intact.

2.2 SAFETY PRECAUTIONS

When installing, operating, and maintaining the
MILROYAL® G pump, keep safety considerations
foremost. Use proper tools, protective clothing, and
eye protection when working on the equipment
and install the equipment with a view toward
ensuring safe operation. Follow the instructions
in this manual and take additional safety
measures appropriate to the liquid being pumped.

Be extremely careful in the presence of hazardous
substances (e.g., Corrosives, toxins, solvents,
acids, caustics, ammables etc.).

2.3 STORAGE

2.3.1 Temporary Storage (Less than 6 Months)

It is preferable to store the material under a shelter
in its original package to protect it from adverse
weather conditions. In condensing atmospheres,
follow the long term storage procedure.

2.3.2 Long Term Storage

(Longer than 6 Months)
Primary Considerations

The primary consideration in storage of pump
equipment is to prevent corrosion of external and
internal components. This corrosion is caused
by natural circulation of air as temperature of the
surroundings change from day to night, day to day,
and from season to season. It is not practical to
prevent this circulation which carries water vapor
and other corrosive gasses, so it is necessary to
protect internal and external surfaces from their
effects to the extent possible.

When the instructions given in this section are
completed, the equipment is to be stored sheltered/
protected from direct exposure to weather.
The prepared equipment should be covered with a
plastic sheet or a tarpaulin, but in a manner which
will allow air circulation and prevent capture of

moisture. Equipment should be stored 12” or more

above the ground.

If equipment is to be shipped directly from
Milton Roy into long term storage, contact
Milton Roy to arrange for factory preparation.

2.3.3 Pump Drive

1. Flood the pump drive housing with a high grade

lubricating oil/rust preventative such as Mobile

Oil Corporation product “Mobilarma 524”.

Fill the housing completely to minimize air space
and water vapor condensation. After storage,

drain this material and rell the equipment to the

correct oil level with the recommended lubricant
for equipment commissioning.

2. Remove drive motor and brush all unpainted

metal surfaces with multipurpose grease

(NLGI grade 2 or 3). Store motor unattached.

5Instruction Manual

SECTION 2 - INSTALLATION

2.3.4 Electrical Equipment

1. Motors should be prepared in the manner

prescribed by their manufacturer. If information
is not available, dismount and store motors as

indicated in step 3 below.

2. Dismount electrical equipment (including

motors) from the pump.

3. For all electrical equipment, place packets of
Vapor Phase Corrosion Inhibitor (VPCI) inside of

the enclosure, then place the entire enclosure,
with additional packets, inside a plastic bag.

Seal the bag tightly closed. Contact Milton Roy
Service Department for recommended VPCI

materials.

2.4 MOUNTING

Support the pump rmly in a level position on a

solid, vibration- free foundation, preferably with

the base above oor level to protect the pump

from wash downs and to provide easier access

for service. Be sure to allow enough space around

the pump for easy access during maintenance

operations, pump adjustments, and/or oil lling or

draining procedures.

MILROYAL® G pumps are provided with mounting
holes to accommodate anchor bolts. Refer to
Figure 3 for mounting hole dimensions.

Some MILROYAL® G pumps are shipped with
motors dismounted. After anchoring pump in
position, install motor, referring to Figure 5.

To avoid damage to pump drive during
operation, make sure spring (360) provided with
pump is installed in worm shaft prior to motor
installation. Pumps installed outdoors should be

protected by a shelter.

2.5 CONVENTION PROCEDURE

A MILROYAL® G pump can, in some cases, be
converted from one liquid end plunger size or
material of construction to another. For more
information on converting between different liquid
end models, please contact the Milton Roy factory
or your local authorized representative.

2.6 PIPING CONNECTIONS

2.6.1 NPSH Considerations

The MILROYAL® G HPD liquid end is far superior
to conventional diaphragm liquid ends for suction

lift and many other NPSH- critical applications.

In these demanding applications, the patented

diaphragm and rell mechanism give this liquid

end truly exceptional performance.

For NPSH apply a 3 psia limitation (instead of
9 psia) in evaluating applications for this liquid end.

Size piping to accommodate peak instantaneous

flow. Because of the reciprocating motion of

the pump diaphragm, pump delivery follows an
approximate sine curve with a peak instantaneous

ow equal to pi (3.14) times the average ow.
Therefore, piping must be designed for a ow

3.14 times the pump capacity; this means that a
pump rated for 100 gallons per hour (379 L/hr.)
requires piping sufcient for 3.14 x 100 gph, or
314 gph (1188 L/hr.).

To minimize viscous ow losses when handling

viscous liquids, it may be necessary to use suction
piping up to four times larger than the size of
the suction connection on the pump. If in doubt,
contact your nearest Milton Roy representative to
determine the necessary pipe size.

6

Instruction Manual

SECTION 2 - INSTALLATION

2.6.2 General Piping Considerations

1. Use extreme care in piping to plastic liquid
end pumps with rigid pipe such as PVC. If any
stresses or vibration are unavoidable, exible

connections are recommended.

2. Use piping materials that will resist corrosion by

the liquid being pumped. Use care in selecting
materials to avoid galvanic corrosion at pump
liquid end connections.

3. Use piping heavy enough to withstand maximum

pressures.

4. Remove burrs, sharp edges, and debris from
inside piping. Blow out all pipelines before
making nal connections to pump.

5. Because vapor in the liquid end will cause

inaccurate pump delivery, piping should be
sloped down to pump suction check valve to
prevent vapor pockets.

6. When pumping suspended solids (such as

slurries), install plugged crosses at all 90° line

turns to permit line cleaning without dismantling
piping.

7. See Figure 4 for a typical recommended pump
installation scheme.

2.6.3 Suction Piping Considerations

1. It is preferable to have the suction of the pump
ooded by locating the liquid end below the

lowest level of the liquid in the supply tank.
Installing the supply vessel on the suction line
in close proximity to the pump will help ensure

a ooded suction line.

2. Avoid negative suction pressure conditions

(suction lift), as such conditions adversely

affect metering accuracy. A lift of 20 Ft. of water

column straight out of a supply tank is the
maximum suction lift permissible.

3. MILROYAL® G pumps are intended to be

operated with process liquid supplied at or
above atmospheric pressure. Although these
pumps can move liquids supplied at less
than atmospheric pressure, in these negative
pressure applications it is important that all
connections be absolutely drip free and vacuum
tight.

4. When pumping a liquid near its boiling point,

provide enough suction head to prevent the

liquid from “ashing” into vapor when it enters

the pump liquid end on the suction stroke.

5. If possible use metal or plastic tubing for the
suction line because such tubing has a smooth
inner surface and can be formed into long,
sweeping bends to minimize frictional flow
losses.

6. A strainer should be used in the suction line to
prevent foreign particles from entering the liquid
end. This and any other measures to prevent
debris from entering and fouling the ball-checks
will give increased maintenance-free service.

Check strainer frequently to prevent blockage

which could lead to cavitation.

7. Keep suction piping as short and straight as

possible.

8. Piping size should be one or two sizes larger

than the liquid end suction tting to prevent

pump starvation.

9. If long suction lines are unavoidable, install a

stand pipe or suction accumulator dampener
near the pump in the suction line.

10. Suction piping must be absolutely airtight to

ensure accurate pumping. After installation,
test suction piping for leaks with air and soap
solution.

7Instruction Manual

SECTION 2 - INSTALLATION

2.6.4 Discharge Piping Considerations

1. Install pipe large enough to prevent excessive

pressure losses on the discharge stroke of the
pump. Maximum pressure at the discharge

tting on the liquid end must be kept at or below

the rated pressure (Max. allowable working
pressure shown on the pump nameplate).

2. The pump will not deliver a controlled ow unless
the discharge line pressure is 35 psi greater than

the suction line pressure. There are a number of

ways to create an articial pressure, such as by

installing a back pressure valve. (Please contact
Milton Roy for recommendations to increase
back pressure in slurry applications.)

3. When pumping water-treatment chemicals

directly into boiler drums, use one liquid
end assembly for each boiler drum.
Discharging into a manifold having the slightest
pressure difference between its several
discharge connections can diminish metering
accuracy as the outlet with the lowest pressure
will receive more liquid than the outer outlets.

2.6.6 Pulsation Dampeners

An accumulator, surge chamber, surge suppressor,
or pulsation dampener should be used with the
back pressure valve in the discharge line to

absorb the ow peaks between the pump and

the back pressure valve. Without the pulsation
dampener the valve mechanism will snap open
and closed with the surge from each pump stroke.
The pulsation dampener will allow the back
pressure valve to oscillate about a partly-closed
position, thus minimizing wear on the valve.
Discharge line pulsation dampeners offer the

further advantage of limiting the ow and pressure

variations characteristic of this kind of pump.
Installing a properly sized pulsation dampener
will improve pump performance and may reduce
system costs dramatically by permitting the
substitution of smaller piping. Please contact
Milton Roy for further information on pulsation
dampeners.

2.6.5 Back Pressure Valves

A Milton Roy Back Pressure Valve should be

installed in the discharge line near the pump to
ensure sufficient discharge head pressure for
proper pump metering action. Normally, the valve

should be located near the pump. However, back

pressure valves for large pumps with long and
extremely small discharge lines may have to
be installed near the point of discharge into the
process (to minimize siphoning tendencies).

8

Instruction Manual

SECTION 2 - INSTALLATION

2.6.7 Pressure Relief Valve (PRV)

Maximum safety and reliability may be ensured by
protecting liquid ends and piping with an external
pressure relief valve installed in the system
discharge line. Although the pump is protected
against excessive pressure by an internal relief
valve, to prevent a blocked discharge line from
causing damage to the piping or process equipment,
install a Milton Roy pressure relief valve in the pump
discharge line. This valve is designed and sized to

handle system ow rates and pressures safely

while resisting corrosion by the process liquid.
Install the safety valve in the discharge line
between the pump and the nearest shut- OFF
valve. (This will prevent potential system damage
from accidental valve closure.) Pipe the pressure
relief valve outlet back to the suction tank or to
drain, but in either case ensure that the pipe end
is continuously visible so pressure relief valve
leakage may be detected. Milton Roy pressure
relief valve must be installed in accordance with its
user manual top of supply tank in order to function
properly.

2.6.8 Check Valves

A check valve should be installed at the point
where the discharge line enters a boiler or other

high-pressure vessel. This will prevent back ow

through the discharge piping and will isolate the
pump discharge from system pressures (a safety
consideration).

2.6.9 Shut- OFF Valves

In order to isolate the pump during maintenance,
provide shut- OFF valves in both suction and
discharge lines next to the pump. Locate discharge
line shut- OFF valve downstream from the inlet
connection of the safety valve. Figure 4 shows
recommended valve locations.

2.7 ELECTRICAL CONNECTIONS

Ensure that the electrical supply matches the pump
motor nameplate characteristics. Before operating

the pump, check the direction of rotation of the
motor to be sure it matches the direction of the
arrow stamped on the motor (rotation should be
clockwise when viewed from the top of the motor).
If motor rotation is incorrect, refer to the motor
data plate or motor manufacturer’s instructions
for reversing.

OPERATION WITH THE WRONG

MOTOR ROTATION WILL DAMAGE

THE PUMP AND MOTOR AND VOID THE WARRANTY.

DO NOT FORGET TO CONNECT

THE PUMP TO AN EARTH

GROUND!

Electric protection of the motor (fuses, overload

meters or relays) should correspond to the rated
current indicated on the motor data plate.

9Instruction Manual

SECTION 3 - OPERATION

3.1 INITIAL START- UP

Check that all mounting bolts are tight, piping is

installed properly, and the discharge line is open.

Check oil drain plug for tightness. Remove the
orange oil ll cap and ll the pump casing until

level is between the top two marks on the oil cap

dipstick. (approximately 3-1/2 quarts). DO NOT
OVERFILL ABOVE TOP DASH!

Note:

The oil furnished with the pump is grade AGMA
No. 5 EP with a viscosity of 1000 SSU at 100°F
(218.4 cSt at 40°C). For operation in ambient
temperatures below 50°F (10°C), substitute
AGMA No. 2 EP with a viscosity of 400 SSU
at 100°F (86.4 cSt at 40°C). Manufacturers’
equivalent oils are shown below.

DO NOT START UP PUMP DRIVE

MOTOR BEFORE FILLING GEAR

BOX WITH OIL OR SERIOUS DAMAGE WILL OCCUR.

Chevron N.L. Gear Compound
220

ABOVE 50°F:

BELOW 50°F:

Food Grade

Alteration

Exxon Spartan E.P. 220

Mobil Mobilgear 630

Texaco Meropa 220

Chevron N.L. Gear Compound 68

Exxon Spartan E.P. 68

Mobil Mobilgear 626

Texaco Meropa 68

Shell Omaha 68

Nevastane EP220

3.1.1 Start- Up for New Pump

For pumps received from the factory, the

displacement chamber (600) is already lled with
oil. Simply remove the orange oil ll cap from the
pump casing and ll the casing with the specied

oil to a level between the top two dashes on the
dipstick. DO NOT OVERFILL ABOVE TOP DASH!
Pump is now ready for operation. Operation of
the air purge button may be required to remove
air that may have come out of solution from the

oil during shipment and storage. Refer to “USE
OF AIR PURGE BUTTON” section for operation

instructions. The integral pump relief valve is

factory adjusted according to customer specied

setting. For instructions on adjustment of the pump
relief valve please refer to the next section.

BEFORE SWITCHING ON POWER

TO THE PUMP, TURN THE

CAPACITY ADJUSTMENT KNOB TO ZERO. CHECK THAT ALL

SHUT- OFF VALVES IN THE SUCTION AND DISCHARGE LINES

ARE OPEN BEFORE INCREASING THE CAPACITY

ADJUSTMENT FROM ZERO.

10

Instruction Manual

SECTION 3 - OPERATION

3.1.2 Start- Up of Pump Containing No Oil
in Casing and Displacement Chamber

The following instructions assume that both the
pump casing and liquid end (displacement chamber)
contain no oil. This condition typically exists when
the pump is subjected to annual maintenance
during which oil may be drained from the pump
casing and oil may escape from the displacement
chamber during diaphragm replacement.
New pumps received from the factory will have

an empty pump casing and a lled displacement

chamber (liquid end). Please refer to the previous
section for start- up of new pumps. After pump

casing is lled to correct oil level (between top two

dashes on oil cap dipstick), perform the following
operations before placing the pump into service.
Numbers refer to item numbers shown in assembly
drawings (Figures 7-9) located in the back of this
manual.

1. Remove hydraulic 3- function valve (refer to
Figure 8):

a. Remove relief valve cap piece (850).

b. Make sure relief valve locknut (900) is tight

to maintain previous relief valve setting upon
start- up.

c. Remove purge button and relief valve

adjustment assembly by removing large

adjustment nut (910).

d. Using needle-nose pliers, remove spring

(950).

e. Using same pliers, remove relief valve poppet

by gently gripping the top of the valve body

(960).

2. Make sure pump capacity adjustment is set to
100%.

3. Fill the opening in the displacement chamber
(600) through the port uncovered by removal
of the 3- function valve in step 1 with the same
oil used to ll the pump casing. Fill the chamber

slowly, allowing air bubbles to escape, until
the oil level reaches the level of the drain tube

(640).

4. Reinstall 3- function valve:

a. Gently gripping the top of the relief valve

poppet (960) with needle-nose pliers, drop

the poppet assembly down into the empty
relief valve port.

b. Drop spring (950) back into relief valve port.

c. Make sure washer (935) is in place above

the O-ring (940) on purge stem (930) and

reinstall purge and relief valve adjustment
assembly by screwing large adjustment nut

(910) back into place. Make sure adjustment
nut (910) is tight.

d. Reinstall relief valve cap piece (850).

5. The pump is now properly lled with oil and ready
for service. If the relief valve locking nut (900)

remained tight during the above procedure, the
relief valve setting should remain unchanged.
If not, refer to next section for instructions on
how to set relief valve.

BEFORE SWITCHING ON POWER

TO THE PUMP, TURN THE CAPACITY

ADJUSTMENT KNOB TO ZERO. CHECK THAT ALL SHUT- OFF VALVES

IN THE SUCTION AND DISCHARGE LINES ARE OPEN BEFORE

INCREASING THE CAPACITY ADJUSTMENT FROM ZERO.

6. Make sure that all air has been bled from the
suction piping and pump head. This can be
accomplished by opening all suction line valves
as well as the system drain (Prime/Air Purge)
valve shown in Figure 4 and allowing uid to ow
into drain until all air has been purged. If drain
valve not present, with the pump capacity set

to 100%, operate the pump under no discharge

pressure until the entire pumping system has

been lled.

11Instruction Manual

SECTION 3 - OPERATION

3.2 RELIEF VALVE ADJUSTMENT

All MILROYAL® G liquid ends have a built in relief

valve which allows hydraulic uid to return to the

pump casing if excessive pressure builds up in the
discharge line. This effectively stops the pump from
pumping, since the forward stroke of the piston

will not displace the hydraulic uid and force the
diaphragm to ex. During operation of the pump, a

relief condition caused by over pressurization can
easily be seen by looking through the sight glass

(630, Figure 7) for excessive oil ow from the drain
tube (640, Figure 8).

Note:

Under normal operation, a few drops of oil

should escape from the drain tube during each

pump stroke due to normal oil ow through the
air bleed ball (970, gure 8). If a stream of oil

from the drain tube is evident on each pump

stroke, the system pressure has exceeded the

pump relief valve setting and the pump is in a

relief condition.

The MILROYAL® G liquid end relief valve may be
adjusted to operating conditions by the following

procedure. Adjust the relief valve after rst installing

the pump and after any maintenance procedures.

THE PRESSURE RELIEF VALVE IS

FACTORY SET TO OPEN AT A

PRESSURE 15% OVER THE CUSTOMER SPECIFIED OPERATING

PRESSURE OR AT 15% ABOVE THE MAXIMUM PRESSURE

RATING OF THE PUMP IF NO OPERATING PRESSURE IS

SPECIFIED BY THE CUSTOMER. WHEN ADJUSTING THE VALVE

SETTING, NEVER SET THE VALVE AT A PRESSURE GREATER

THAN 15% OVER THE PUMP MAXIMUM PRESSURE RATING.

3.2.1 Relief Valve Adjustment (With an
Adjustable System Back pressure Valve).
Refer to Figures 7 & 8.

The following procedure assumes that a back
pressure valve and pressure gauge are installed
in the discharge line. If these components are not
installed, refer to next section.

1. Make sure all system shut- OFF valves are

open and that the back pressure valve is backed

out to allow for ow against zero discharge

pressure.

2. Start pump and set capacity at 100%. If a drain

valve is present in the discharge line, pump
process liquid to drain or other safe point to

establish proper pumping action. Close drain.

3. Slowly increase system pressure until:

a. Signicant ow is observed from the drain

tube (640, gure 8) as viewed through the
sight glass (630, gure 7) or

b. The system pressure reaches 15% over the

desired system pressure.

4. For condition (a) in step 4, if relief condition
occurs at less than 15% above desired pump

operating pressure, the relief valve setting
must be increased. Remove valve cover

(850) and increase relief valve setting by
turning the adjustment screw (890) clockwise

until only a few drops of oil escape on each
pump stroke (normal leakage past air bleed

ball-980). Increase system pressure to 15%

above desired operating pressure to verify that
pump is now in relief condition. If it is not, reduce
relief valve setting by turning adjustment screw

(890) counterclockwise until relief is observed

in sight glass drain tube at a pressure equal to

15% greater than desired operating pressure.

Lock-in relief valve setting by tightening locking

nut (900) while holding adjustment screw (890)

stationary. The relief valve is now properly

adjusted. Reinstall valve cover (850).

5. For condition (b) in step 4, the setting of the

relief valve should be reduced. Remove valve

cover (850) and turn adjustment screw (890)

counterclockwise until relief is observed in
sight glass drain tube at a pressure equal to

15% greater than desired operating pressure.

Lock-in relief valve setting by tightening locking

nut (900) while holding adjustment screw (890)

stationary. The relief valve is now properly

adjusted. Reinstall valve cover (850).

12

Instruction Manual

SECTION 3 - OPERATION

3.2.2 Relief Valve Adjustment (Without an
Adjustable System Back Pressure Valve).

If no adjustable back pressure valve is present

in the discharge line, use the following simplied

procedure to check and/or set the relief valve
setting.

1. If pump is in a relief condition at normal

operating pressure, the relief valve setting

should be increased. Remove valve cover (850)

and increase relief valve setting by turning the

adjustment screw (890) clockwise until only a

few drops of oil escape on each pump stroke

(normal leakage past air bleed ball) (970).

Turn adjustment screw an additional ½ turn to
provide an adequate buffer zone. Lock-in relief

valve setting by tightening locking nut (900)
while holding adjustment screw (890) stationary.

The relief valve is now properly adjusted.

Reinstall valve cover (850).

2. If pump is not in a relief condition at normal

operating pressure, and the operator wishes

to reset the valve setting to approximately 15%

above operating pressure(recommended),
use the following procedure. Remove valve

cover (850) and decrease the relief valve
setting by turning the adjustment screw (890)
counterclockwise until a stream of oil ows
from the drain tube (640) on each pump stroke.

Now slowly turn adjustment screw clockwise
until only a few drops of oil escape on each
pump stroke (normal leakage past air bleed
ball). Turn screw an additional ½ turn to provide
an adequate buffer zone. Lock-in relief valve

setting by tightening locking nut (900) while
holding adjustment screw (890) stationary.

The relief valve is now properly adjusted.

Reinstall valve cover (850).

3.3 USE OF AIR PURGE BUTTON
Refer to Figure 7 & 8:

As with any hydraulically actuated diaphragm
pump, dissolved air will come out of solution
during normal operation which can negatively
impact pump performance if not removed
from the pump displacement chamber.
The MILROYAL® G hydraulic 3- function valve is
equipped with two mechanisms for removal of this
gas: a continuous air bleed and an air purge button.
The continuous air bleed portion of the valve is

composed of a sealed ball (970) which allows for a

controlled leakage of a few drops of oil, and any small
accumulations of evolved gas, on each pump stroke.
Larger quantities of air can be quickly removed by

pressing the spring-loaded purge button (860), until

it reaches its mechanical stop, for a few seconds.
Upon doing so, the operator will observe a stream

of oil and air escaping from the drain tube (640).

The need for use of the purge button to remove
a large quantity of air can be caused by several
factors:

1. Blocked suction line: A partially or fully blocked

suction line can create a vacuum pressure
condition in the hydraulic system which pulls
significant quantities of dissolved gas from
solution.

2. Oil Change: The recommended annual

changing of the oil in the pump drive can lead to
the presence of air pockets in the displacement

chamber (600).

3. Diaphragm Replacement: Results in signicant

loss of oil from the displacement chamber.

4. Pump Start- up After Long Idle Period: If the
pump has sat idle for a signicant time, gas

may come out of solution from the oil and collect
into pockets which can negatively impact pump

ow. Depression of the purge button will quickly

evacuate these pockets and restore the pump
to desired performance.

13Instruction Manual

SECTION 3 - OPERATION

The operator should only activate the purge button
if some type of pump upset occurs such as the

above 4 examples. When activating the purge, only
press button for 2-3 seconds or until a stream of oil
owing from the drain tube (640) is seen through
the sight glass (630). Immediately after activation
of the purge button, a temporary reduction in ow
will occur as the rell system replenishes oil lost
during the purge. However, the pump should return
to normal operation within 1 to 2 minutes after

activation of the purge button. If after that time, the

pump ow rate is still less than it should be, repeat
the purge operation and wait another 2 minutes.
If ow has still not resumed to expected levels,

consult the troubleshooting section of this manual.

3.4 MANUAL CAPACITY CONTROL

To adjust pump capacity on standard pumps
equipped with manual stroke adjustment, first
loosen the stroke locking screw located in
the pump side cover. Pump capacity is then
adjusted by turning the micrometer-type stroke
adjustment knob clockwise to decrease capacity or
counterclockwise to increase capacity as required.

The adjustment scale is marked in percent (%)

of full stroke, with calibration lines on the knob at

1% intervals. After adjusting the knob to the desired

capacity setting, hand tighten the stroke locking
screw to maintain the capacity setting.

3.5 FILLING PUMPING SYSTEM

For proper pump operation, it is especially important
that pump suction and discharge lines be free of
entrained air. To ensure this condition, operate the

pump without any discharge pressure and ll the

entire pumping system with liquid before starting
pressure tests. A simple method to assure priming
of the pump is to install a tee and a shut- OFF valve
at the discharge connection of the pump.

If the pump is idle for long periods, temperature
changes in the process liquid may produce air in
the system. To discharge the air, install a valve in
the discharge line which will allow the process liquid
to be pumped to a drain when starting the pump.

3.6 CAPACITY CALIBRATION

After the rst 12 hours of operation, the pump
should be tested and calibrated to nd the exact
pump capacity under specic operating conditions
and capacity settings for the specic uid being
pumped. Typically, calibrating the pump at 100,
50, and 10 percent capacity settings is enough to

establish a pump performance curve throughout
the adjustment range.

The pump can be calibrated by measuring the
decrease in liquid level pumped from a calibrated
vessel. This method is recommended for hazardous
liquids because it eliminates operator contact

with the liquid. Milton Roy test-tube Calibration
Columns are available for convenient and accurate

calibration of any pump. The pump can also be
calibrated by collecting and measuring pumped
liquid at the pump discharge port in which case it
will be necessary to create discharge head at the
liquid takeoff point so that the pump will operate
properly. (See Section 2 for recommended ways

to do this.)

14

THIS METHOD IS NOT

GENERALLY RECOMMENDED

AS IT MAY EXPOSE OPERATING PERSONNEL TO HAZARDOUS

LIQUIDS.

Instruction Manual

SECTION 4 - MAINTENANCE

4.1 RECOMMENDED SPARE PARTS

To avoid delays in repairs, a Routine Preventative

Maintenance Kit should be ordered for each pump.

The RPM kit contains an oil strainer and check
valve parts. Part orders must include the following
information:

1. Quantity required.

2. Part Number.

3. Part Description.

4. Pump serial number (found on pump

nameplate).

5. Pump model number (found on pump
nameplate).

6. Pump product code (found on pump
nameplate).

Always include the serial number, model number,
and product code in all correspondence regarding
this unit.

4.2 SHIPPING PUMPS FOR REPAIR

Pumps can not be accepted for repair without a
Return Material Authorization. Pumps should be
clearly labeled to indicate the liquid being pumped.

Process liquid should be ushed from the pump

liquid end and oil should be drained from the pump
housing and displacement chamber. To drain oil

from the displacement chamber, unscrew the rell
valve body (660, gure 8) from the displacement

chamber. Allow oil to drain into a waste container.

Remove diaphragm (510) and tilt up the back of

the pump until oil ceases to drain from the front of
the pump.

Note:

Federal law prohibits handling of equipment
that is not accompanied by an OSHA Safety
Data Sheet (SDS). A completed SDS must be
packed in the shipping crate with any pump
shipped for repair. These safety precautions will

aid the troubleshooting and repair procedure

and preclude serious injury to repair personnel
from hazardous residue in pump liquid end.
A Safety Data Sheet must accompany all
returns.

All inquiries or parts orders should be addressed to
your local Milton Roy representative or distributor.

4.3 ROUTINE PREVENTATIVE
MAINTENANCE

BEFORE ANY MAINTENANCE,

RELIEVE ALL PRESSURE

FROM SYSTEM, ISOLATE LIQUID END FROM ALL SOURCES

OF PROCESS LIQUID WITH APPROPRIATE VALVING, AND

PURGE LIQUID END OF ALL PROCESS LIQUID.

4.3.1 Oil Replacement

I n i t i a l l y , c h a n g e o i l i n p u m p c a s i n g a f t e r t h e  r s t
250 hours of operation. Then change oil after
every 4000 hours of operation or every six months

whichever comes first. Oil can be drained by

removing the drain plug (20, gure 6). When oil
has nished draining, make sure that the area

around the drain hole is clean. Screw drain plug
back in securely. Fill the pump housing with
the recommended oil until the level is between
the top two marks on the dipstick. DO NOT
OVERFILL(above top mark)! Replace the oil

ll cap and screw rmly in place. Dispose of oil

according to any federal, state or local codes which
may apply.

Note:

It is not necessary to purge the liquid end

displacement chamber of oil during annual oil

replacement.

15Instruction Manual

SECTION 4 - MAINTENANCE

4.3.2 Check Valves

Milton Roy recommends that check valve balls,
seats, gaskets, and O-rings be replaced on an
annual basis. If highly corrosive material (acids,
slurries etc.) is being pumped, some applications
may require more frequent replacement.
Milton Roy recommends an annual tune up using

a Routine Preventive Maintenance (RPM) Kit.

RPM kits contain replacements for those parts

which are subject to wear; specically the ball

checks, check valve seats, gaskets/seals, and the
strainer. Replacing these parts annually with an
RPM kit can reduce the possibility of unexpected
downtime and will help to extend pump life.

To determine if check valves need maintenance,
disassemble the check valves following the

instructions in the following “Check Valve
Replacement” section. In valves that permit

disassembly, inspect the ball check and seat for
chemical or physical damage. The ball should be
perfectly round and free of pits, marks, or scratches.
The seat should retain a smooth edge where the
ball contacts for proper sealing. If the seat edge
is worn or damaged, or has any pits, marks, or
scratches, it should be replaced. If the ball and/
or seat is excessively damaged, the replacement
schedule should be shortened accordingly.
If the ball and seat are both in good condition, the
replacement schedule can be lengthened.

BEFORE CARRYING OUT ANY

SERVICING OPERATION ON THE

METERING UNIT OR PIPES, DISCONNECT ELECTRICAL

POWER FROM THE PUMP, AND TAKE THE NECESSARY STEPS

TO ENSURE THAT THE HARMFUL LIQUID THEY CONTAIN

CANNOT ESCAPE OR COME INTO CONTACT WITH

PERSONNEL. SUITABLE PROTECTIVE EQUIPMENT MUST BE

PROVIDED. CHECK THAT THERE IS NO SYSTEM FLUID

PRESSURE BEFORE PROCEEDING WITH DISMANTLING OF

LIQUID END COMPONENTS.

4.3.3 Cleaning Fouled Check Valves

Check valve assemblies are designed to be self

cleaning and should seldom need servicing.
Fouled check valves can usually be cleaned by
pumping a solution of mild detergent and warm
water (if compatible with liquid being pumped) for

15 minutes, followed by ushing with water.

4.3.4 Check Valve Replacement

Before beginning work on the valve assemblies,

make sure the shut- OFF valves are closed and
that pressure has been bled from the system. When
replacing the valves, take care to systematically
change their O-rings and/or gaskets. Take care to
properly assemble the valve assemblies. In valves
that permit replacement of ball and seat, the ball
must be placed on the sharp edge of the seats.

For each plunger size, check valves are supplied

in three different congurations: plastic- single

ball, plastic-double ball, and metallic- double ball.

Be sure to refer to the appropriate instructional set

below pertaining to your plunger size and valve
type.

BE SURE TO FOLLOW

INSTRUCTIONS CAREFULLY

AND REFER TO THE APPROPRIATE FIGURE WHEN

REASSEMBLING CHECK VALVES. IF CHECK VALVE

CARTRIDGES ARE INSTALLED INCORRECTLY, ONE OF THE

FOLLOWING WILL OCCUR: (A) IMMEDIATE SEVERE DAMAGE

TO PUMP MECHANISM, (B) NO PUMPING, (C) REVERSE

PUMPING ACTION (FROM DISCHARGE LINE INTO SUCTION

LINE).

16

Instruction Manual

SECTION 4 - MAINTENANCE

1-1/4” Plunger;Plastic Single Ball Check
Valves: see Figure 12

1. Unscrew the valve body (445).

2. Remove the cartridge assembly (425): includes

cartridge (ball, seat, ball guide), O-ring, and
washer.

3. Clean the valve housing and mating port in the

liquid end.

4. Press a new clear plastic washer into valve

body.

5. Install new cartridge valve assembly in
orientation shown in gure 12.

• Make sure that seat end of cartridge (white)

is always facing down.

• On discharge side, drop cartridge assembly

into threaded port in head. The O-ring should
be stretched around outside of cartridge on
same end as ball seat. Screw valve body into
discharge side of diaphragm head until valve
is hand tight. Do not overtighten.

• On suction side, drop cartridge assembly

into check valve body. The O-ring should
be stretched around outside of cartridge on
opposite end of ball seat. Screw suction valve
housing with cartridge valve into suction side
of head. Do not overtighten.

1-1/4” Plunger; Metallic Double Ball Check
Valves: see Figure 13

The metallic check valves used on the 1-1/4”

plunger size pumps are precision assembled at
the factory. Do not attempt to disassemble these

cartridges. If they become inoperative, ush them

with solvent, wash them with warm detergent and
blow them out with compressed air to remove any
foreign matter. If this treatment does not eliminate
the trouble, the cartridge assembly should be
replaced.

A. Disassembly (refer to gure 13)

1. The check valve cartridge assemblies use
an SAE straight thread with an O-ring seal to

facilitate port alignment with the connecting
pipes. To remove the cartridge from the liquid

end, rst loosen the lock nut (435) one or two
threads, then unscrew the cartridge (444,

445).

2. Remove and discard the O-ring (441) and split
ring (439).

3. Carefully clean any parts to be reused. If any

chemicals are used in the cleaning process,
ensure that they are compatible with the process
liquid.

17Instruction Manual

SECTION 4 - MAINTENANCE

B. Reassembly (refer to gure 13)

1. To install the cartridge, position the lock nut
(435) toward the shoulder of the cartridge so

that the recess on the face of the lock nut is

adjacent to the O-ring (441).

2. Make certain the split ring (439) is coiled in

a counterclockwise helix(this is opposite the
direction normally employed by suppliers of
these rings). Fit this split ring in the lock nut

recess. Push it rmly down in the recess as

completely as possible.

3. Install a new O-ring (435) against the split

ring.

Note:

To assure a tight, leak free seal, new O-rings

and split rings should be used each time the

check valves are disassembled.

4. Screw the cartridge assembly (444, 445) into the

liquid end until the O-ring band is approximately
level with the top of the spot face in the liquid

end, then screw it one (1) additional turn plus a

partial turn as required to align the pipe thread
port with connecting pipe.

1-3/4, 2-1/2, and 3”Plungers: Plastic Single- Ball
Check Valves: see Figure 11

A. Disassembly

1. Unscrew the union nut (435). The union end
(445) is held in place by the union nut and will

now separate easily from check valve ball guide

(424).

2. Unscrew the ball guide (424) from the liquid

end.

3. Screw the union nut partially (one or two turns)

onto the end of the ball guide containing the

seat. Be sure the union nut is loosely installed
to allow for a gap for the seat (420) to drop into

as it is removed from the ball guide.

4. Sit the ball guide/union nut onto a at surface

with the union nut down. Looking into the top
of the ball guide, you will see four large holes
surrounding one small hole. Insert a thin, blunt
instrument such as a hex head screwdriver into
the small center hole until it rests on the top of

the ball (422).

5. Tap screwdriver gently with a hammer until ball
and seat are released from the ball guide.

SUCTION AND DISCHARGE

CHECK VALVE CARTRIDGES

ARE NOT IDENTICAL. BE SURE THAT THE CORRECT

CARTRIDGE IS BEING SCREWED INTO THE PROPER PORT.

(DISCHARGE CARTRIDGES HAVE HEXAGONAL CAP ON THE

TOP; SUCTION CARTRIDGES DO NOT.) IF CHECK VALVE

CARTRIDGES ARE INSTALLED INTO THE WRONG PORT, ONE

OF THE FOLLOWING WILL OCCUR: (A) IMMEDIATE SEVERE

DAMAGE TO PUMP MECHANISM, (B) NO PUMPING, (C)

REVERSE PUMPING ACTION (FRONT DISCHARGE LINE INTO

SUCTION LINE).

5. After completing pipe connection, tighten lock
nut securely against spot face so that O-ring is
trapped in chamfer of liquid end thread. Make
sure that the split ring is completely contained in
its recess and not extending to the outside.

18

Instruction Manual

IF YOU ARE DISASSEMBLING

UNIT FOR INSPECTION ONLY,

BE SURE TO USE A BLUNT INSTRUMENT AND TAP GENTLY TO

AVOID DAMAGING THE BALL. IF THE BALL AND/OR SEAT ARE

DAMAGED DURING DISASSEMBLY, THEY WILL NEED TO BE

REPLACED. TO AVOID DAMAGE, IF AVAILABLE, IT IS

ADVISABLE TO USE GENTLE AIR PRESSURE (APPLIED AT

END OPPOSITE THE SEAT-420) FOR BALL AND SEAT

REMOVAL.

6. Carefully remove the two O-rings (419) from the

ball guide and seat.

SECTION 4 - MAINTENANCE

7. Inspect the balls carefully. If they are smooth,

round and free of deposits or pits, they are

suitable for continued use. Examine the check

valve seats. The area of the seat in contact
with the ball (the un-chamfered side) must be
in near perfect condition for continued use.
Any visible imperfection on the seating surface
(pits, erosion, cracks) necessitates replacement
of the seat. If both the balls and the seats are in
good condition, then the length of time between
parts replacement may be increased. If the
balls and seats are severely damaged, then
the length of time between parts replacement

should be shortened. Carefully clean any

parts to be reused. If any chemicals are used
in the cleaning process, ensure that they are
compatible with the process liquid.

B. Reassembly

1. Drop the ball into the curved inner chamber end

of the ball guide.

2. Sit the ball guide on a at surface so that the side

with the ball faces upwards. Position seat on the
ball guide, trapping the ball inside. When the
seat is pressed into the ball guide, the beveled
edge of the seat must be facing outward.
The bevel should not face the inside of the check
valve (refer to Figure 11). Use a at surface such
as a board to press the seat into the ball guide

with rm, even pressure.

IF THE SEAT IS IMPROPERLY

POSITIONED (WITH BALL

AGAINST BEVELED SURFACE), THE BALL WILL NOT CREATE

A TIGHT SEAL AND POOR PUMPING PERFORMANCE WILL

RESULT.

3. Fit new O-rings into grooves in the ball guide

and seat.

Note:

To assure a tight, leak free seal, new O-rings
should be used each time the check valves are
disassembled.

4. Position the union end (445) onto the correct

end of the ball guide. Refer to Figure 11 as the
correct end is determined by whether the valve
is intended for the suction or discharge port of

the liquid end. Slip the union nut (435) over the

union end and screw tightly (hand tight only)
onto the ball guide.

THE ORDER OF ASSEMBLY OF

THE SUCTION AND DISCHARGE

CHECK VALVES IS DIFFERENT. REFER TO FIGURE 11 FOR

PROPER ASSEMBLY ORDER. IF CHECK VALVE CARTRIDGES

ARE INSTALLED INCORRECTLY, ONE OF THE FOLLOWING

WILL OCCUR: (A) IMMEDIATE SEVERE DAMAGE TO PUMP

MECHANISM, (B) NO PUMPING, (C) REVERSE PUMPING

ACTION (FROM DISCHARGE LINE INTO SUCTION LINE).

5. Screw the valve assembly into the liquid
end body(hand tight only). DO NOT

OVERTIGHTEN!

1-1/4” Plunger, Plastic Double Ball Check
Valves 1-3/4”, 2-1/2”, 3” Plungers, Plastic &

Metallic Double Ball Check Valves

A. Disassembly (Refer to Figure 10).

Double ball check valves differ from the plastic
single ball check in that the ball seat is now
integral to the ball guide. The seats cannot easily
be inspected for damage or wear. If you suspect
that the check valve may be damaged or worn,
replace the entire check valve assembly as per
instructions below.

1. If metallic valve, unscrew the coupling (445)
from the ball guide (424). If plastic, unscrew the
union nut (435, gure 11) and remove union end
(445, gure 11) from the ball guide (424).

2. Unscrew the ball guide (424) from the liquid

end.

3. Remove and discard the O-rings (419).

4. Remove ball stop (420) and balls (421, 422).

19Instruction Manual

SECTION 4 - MAINTENANCE

Inspect the balls carefully. If they are smooth,
round and free of deposits or pits, they are

suitable for continued use. Examine the ball
seat areas in the valve body (424). A magnifying

glass is recommended for this inspection.
The seat must be in near perfect condition for
continued use. Any visible imperfection on the
seating surface (pits, erosion, cracks) renders
the seat unusable thereby requiring replacement

of the valve body (424). If both the balls and the

seats are in good condition, then the length
of time between parts replacement may be
increased. If the balls and seats are severely
damaged, then the length of time between parts

replacement should be shortened. Carefully

clean any parts to be reused. If any chemicals
are used in the cleaning process, ensure that
they are compatible with the process liquid.

B. Reassembly (Refer to Figure 10):

1. Drop the balls (422, 421) into the valve body
(424). Drop ball stop (420) into place making

sure that side with O-ring groove is facing up.

Install new O-rings (419) on both ends of valve

body.

(445) onto the check valve assembly, trapping
a new O-ring (419) between the coupling and

the check valve assembly. If plastic check

valve, position the union end (445) onto the

correct end of the ball guide. Slip the union

nut (435) over the union end and screw tightly

(hand tight only) onto the ball guide. DO NOT
OVERTIGHTEN!

4.3.5 Oil Strainer Replacement
Refer to Figure 8.

Over time, the oil strainer (670) which screws into
the rell valve body (660) can become fouled or

clogged. It should therefore be replaced yearly
and is included with the check valve parts in the

RPM Kit. If the strainer becomes clogged more

frequently than once a year (which is extremely
unlikely), it can be ordered separately.

Since the oil must rst be drained from the pump

casing, it is a good idea to schedule strainer
replacement with oil replacement.

1. Drain oil as described in the above “Oil
Replacement” section of this manual.

2. Unscrew the strainer (670) from the rell valve
body (660).

Note:

To assure a tight, leak free seal, new O-rings
should be used each time the check valves are
disassembled.

2. Screw the correct end of the check valve

assembly into the liquid end (hand tight only)
trapping a new O-ring between the liquid
end and the check valve assembly. DO NOT

OVERTIGHTEN!

THE END OF THE CHECK VALVE

THAT IS SCREWED INTO THE

PUMP HEAD IS DIFFERENT FOR THE SUCTION AND

DISCHARGE CHECK VALVES. REFER TO FIGURE 10 FOR

PROPER ASSEMBLY ORDER. IF CHECK VALVE CARTRIDGES

ARE INSTALLED INCORRECTLY, ONE OF THE FOLLOWING

WILL OCCUR: (A) IMMEDIATE SEVERE DAMAGE TO PUMP

MECHANISM, (B) NO PUMPING, (C) REVERSE PUMPING

ACTION (FROM DISCHARGE LINE INTO SUCTION LINE).

3. If metallic check valve, screw the coupling

20

Instruction Manual

3. Clean any debris from the strainer cavity in the

valve body.

4. Screw a new strainer into the rell valve body.

5. Rell pump casing with recommended oil as
described in the “Oil Replacement” section.

SECTION 4 - MAINTENANCE

4.4 CORRECTIVE MAINTENANCE

4.4.1 3- Function Hydraulic Valve

The 3- function hydraulic valve assembly
(see Figure 8) operates in ltered hydraulic oil

and should require maintenance only if unusual
circumstances occur, such as if corrosive media

contaminates the uid.

Assembly and disassembly is straightforward.
Follow instructions in the “Start- Up of Pump

Containing No Oil in Casing and Displacement
Chamber” section of the manual. Field servicing

should be limited to inspection and cleaning only.
Repairs of this critical component should only be
carried out by an authorized Milton Roy repair
facility.

4.4.2 “MARS” Valve Assembly

The Mechanically Activated Rell System (MARS)

valve assembly (see Figures 8 & 9) requires no

periodic maintenance. Clean hydraulic oil is critical

for proper operation. Field servicing should be
limited to inspection and cleaning only. Repairs of
this critical component should only be carried out
by an authorized Milton Roy repair facility.

The valve is designed to be easily removed through
the front of the pump without having to remove
the displacement chamber. The following steps
describe the procedure for removal of the valve
from the displacement chamber (refer to Figure 9):

A. Disassembly

1. Remove liquid end according to instructions
in the “Removing the Liquid End” portion of

the “Diaphragm Replacement” section of the
manual.

2. Insert a small tip screw driver into one of the two
small holes in the valve button (780) and gently
pry out plastic cap (790).

4. Slide OFF activation button (780) and spring
(800).

5. Remove large retaining ring (810) using the

appropriate retaining ring pliers (Waldes Truarc

Internal Type, Waldes Truarc part# 0300).

6. Reinstall small retaining ring (820) in groove in
valve stem (770).

7. To avoid damage to valve stem, grip retaining

ring with pliers and pull remaining valve
assembly out of displacement chamber.

8. Discard O-rings (830,840) and retaining rings
(810, 820).

NOTE:

When reinstalling, make certain that new
O-rings and retaining rings are installed on
MARS assembly.

B. Reassembly

1. Install new O-rings (830, 840) on valve body
(750) and apply a light layer of O-ring grease

to O-rings.

2. Push assembly into place until it reaches stop

in displacement chamber.

3. Reinstall large bowed retaining ring (810).
Using a hammer and at tipped screwdriver,

gently tap the ring to insure that it is securely
seated in the retaining groove machined into
the displacement chamber.

4. Reinstall spring (800) and activation button
(780).

5. While pressing button (780), reinstall small
retaining ring (820). Gently tap on the ring to

insure that it is securely seated in the retaining
ring groove machined into the valve stem

(770).

6. Press plastic cap piece (790) into activation
button (780).

3. While pressing down on button (780), remove
the retaining ring (820) using the appropriate
retaining ring pliers (Waldes Truarc External
Type, Waldes Truarc part# M-1520).

7. Valve is now ready for service.

21Instruction Manual

SECTION 4 - MAINTENANCE

4.4.3RellValveAssembly(see Figure 8).

The only required periodic maintenance for the
refill valve assembly is the suggested annual
replacement of the oil strainer (see above “Oil

Strainer Replacement” section). Clean hydraulic

oil is critical for proper operation. Field servicing
of the valve assembly is limited to inspection and
cleaning only. Repairs of this critical component
should only be carried out by an authorized
Milton Roy repair facility.

The valve is designed to be easily removed through
the bottom of the pump without having to remove
the displacement chamber. The following steps
describe the procedure for removal of the valve
from the displacement chamber (Figure 8):

A. Disassembly

1. Drain oil from the pump housing as described
in the above “Oil Replacement” section.

2. Unscrew the valve body (660) from the
displacement chamber (600).

3. Clean any debris from the valve cavity in the

displacement chamber.

4. Discard O-rings (720, 730).

Note:

When reinstalling the valve assembly, be sure
to install new O-rings (720, 730).

B. Reassembly

4.4.4 Diaphragm Replacement

MILROYAL® G liquid ends are designed to
provide reliable service under normal operating
circumstances and should not require replacement

of the diaphragm. However, in the unlikely event

of a failure, the diaphragm can be replaced by the
following the procedure:

A. Removal of Diaphragm (Figures 7 & 8):

BEFORE BEGINNING DISASSEMBLY

PROCEDURES, RELIEVE ALL

PRESSURE FROM SYSTEM, ISOLATE THE LIQUID END FROM ALL

SOURCES OF PROCESS LIQUID WITH APPROPRIATE VALVING, AND

PURGE LIQUID END OF ALL PROCESS LIQUID.

1. Disconnect both the suction inlet and discharge

outlet from the piping system.

2. Locate drain pan under diaphragm head to
collect oil. Approximately 1 pint of oil will drain

from the displacement chamber after removal
of the diaphragm.

3. Remove the diaphragm head bolts (1025) which

hold the head to the displacement chamber and

remove diaphragm head (1020). Oil will begin to
leak out. In most cases, the white teon-faced

diaphragm will remain in the displacement
chamber.

4. Remove the diaphragm. Oil will now drain out

of the front of the displacement chamber.

1. Install new O-rings (720, 730) and coat rings

with O-ring grease.

2. Screw valve assembly back into displacement

chamber until it reaches mechanical stop.

3. Make sure the strainer (670) is installed and
strainer plug (650) is tight. Valve is now ready for
service. Rell pump casing with recommended
oil as described in the “Oil Replacement”

section.

22

Instruction Manual

SECTION 4 - MAINTENANCE

B. Installation of New Diaphragm
(Figures 7 & 8):

1. Make sure the contoured diaphragm support

surface and O-ring groove machined into
displacement chamber are clean. To prevent
leakage from occurring, be careful not to scratch
the O-ring groove when cleaning.

2. Install the diaphragm into the displacement

chamber with the black rubber side against
the contoured surface of the displacement
chamber. Make sure the diaphragm sealing

bead ts securely in the diaphragm groove of the
displacement chamber. The white teon-face of

the diaphragm should be facing outward and
visible.

3. Align the two holes in the diaphragm head with the
locating pins (610) in the displacement chamber
and reinstall diaphragm head (1020).

4. Reinstall head bolts (1025), at washer (1040),
lock washers (1035), and nuts (1030).

5. Tighten bolts rmly in a crisscross pattern.

4.4.5 Removal of Pump Liquid End

(Figures 7 & 8)

MILROYAL® G liquid ends are designed to
provide reliable service under normal operating
circumstances and should not require removal

of the liquid end. However, if the need arises, the

following describes the procedure.

BEFORE BEGINNING DISASSEMBLY

PROCEDURES, RELIEVE ALL

PRESSURE FROM SYSTEM, ISOLATE THE LIQUID END FROM ALL

SOURCES OF PROCESS LIQUID WITH APPROPRIATE VALVING, AND

PURGE LIQUID END OF ALL PROCESS LIQUID.

A. Disassembly:

1. Disconnect both the suction inlet and discharge

outlet from the piping system.

2. Drain oil as described in the above “Oil
Replacement” section of this manual.

3. Remove 3- Function Valve assembly as
described in the “Start- Up of Pump Containing
No Oil in Casing and Displacement Chamber”.

4. Remove six displacement chamber bolts (570)
and lock washers (560) which secure liquid end

to pump drive housing.

5. Locate a container under liquid end to catch

approximately 1 pint of oil that will escape during

next step.

6. Gently pull liquid end OFF drive housing
being careful to avoid damage to plunger
(520, gure 5) during removal. Drain oil into
waste container.

7. Discard displacement chamber gasket (590).

8. Place the liquid end, diaphragm head up, on

a bench or other clean, at, convenient work

area.

B. Reassembly:

1. Make sure gasket surface on pump housing

and displacement chamber are clean and free
of markings which could serve as leak paths.

2. Install new displacement chamber gasket (590)

in correct orientation on liquid end.

3. With vent cap (620) at 12 O’clock, gently slide

liquid end over plunger.

4. Reinstall six displacement chamber bolts (570)
and lock washers (560) and tighten securely.

5. Follow procedure for filling pump housing
and liquid end with oil described in “Start- Up

of Pump Containing No Oil in Casing and
Displacement Chamber”.

23Instruction Manual

SECTION 5 - TROUBLESHOOTING

5.1 SYMPTOMS & REMEDIES

• Low process liquid level in tank. Add liquid.

• Worn or dirty check valves. Clean or replace.

• Blocked discharge line. Clear line.

• Frozen liquid: Thaw liquid throughout pumping system.

Pump will not
operate

Insufcient delivery

Erratic delivery

• Blown fuse. Replace fuse.

• Open thermal overload device in motor starter. Reset device.

• Broken wire. Locate and repair.

• Low voltage: Investigate and correct (wiring may be too light).

• Pump not primed. Allow suction line and pump head to ll with liquid before
pumping against pressure. Refer to “Filling Pumping System” in Section 3.

• Capacity adjustment set at zero. Readjust capacity.

• Relief valve relieving.

• Blocked discharge line. Clear line.

• Relief valve set too low. Adjust valve to 15% over operating pressure.

• Air in hydraulic system. Operate purge button.

• Clogged rell line: Remove oil strainer and clean or replace.

• Incorrect capacity adjustment: Readjust capacity setting.

• Incorrect pump speed. Match line voltage and frequency to pump motor data plate.

• Starved suction. Increase piping size or suction head.

• Leaky suction piping. Repair piping.

• High suction lift (Insufcient NPSH). Most common with long suction lines, small

diameter suction lines, acid pumping, polymer (viscous) liquids, or drawing from

a source lower than pump. Consult your local representative or the Milton Roy

Factory Aftermarket Department.

• Liquid near boiling. Cool liquid or increase suction head.

• Leaky safety valve in discharge line. Repair or replace safety valve.

• High liquid viscosity. Reduce viscosity (e.g., heat or dilute liquid).

• Worn or dirty check valve seats. Clean or replace.

• Leaky relief valve. Repair or replace valve (consult factory).

• Leaky suction piping. Repair piping.

• Leaky safety valve. Repair or replace safety valve.

• Liquid near boiling. Cool liquid or increase suction head.

• Worn or dirty check valves. Clean or replace.

• Blocked suction line. Clean strainer.

• High suction lift (Insufcient NPSH). Most common with long suction lines, small

diameter suction lines, acid pumping, polymer (viscous) liquids, or drawing from

a source lower than pump. Consult your local representative or the Milton Roy

Factor Aftermarket Department.

24

Instruction Manual

SECTION 5 - TROUBLESHOOTING

Excessive Delivery

Motor and pump
body hot

Pump still pumps
even at zero
capacity setting

Gear noise.

Loud knock with
each stroke

Noisy operation in
liquid end

• Low discharge line pressure. Increase line pressure

(e.g., install a back pressure valve).

• Normal operating temperature of both motor and pump body is frequently
uncomfortable to the touch. However, neither should exceed 200°F (93°C).

• Power supply does not match electrical requirement of motor. Insure proper

matching of power supply and motor.

• Pump is being operated at greater than rated performance. Reduce pressure or

stroke speed. If this is not practical, contact service facility.

• Pump improperly lubricated. Drain oil and rell with proper amount of

recommended lubricant.

• Misadjusted micrometer knob. Readjust capacity setting.

• Insufcient discharge pressure. Correct condition

(e.g., install a back pressure valve).

• Excessive backlash. Consult service facility.

• Worn bearings. Consult service facility.

• Wrong or insufcient lubricant. Replace or replenish lubricant.

• Excessive gear set wear. Consult service facility.

• Worn bearings. Consult service facility.

• Incorrect motor rotation. Should be clockwise as viewed from top of motor.

• Worm shaft spring (360) missing.

• Noise in check valves. Ball checks move up and down with some force.
A distinct “clicking” noise is normal, especially in metal piping systems.

25Instruction Manual

SECTION 6 - PART NUMBERS

6.1 BASIC PARTS LIST- PUMP DRIVE
(Refer to Figure 5 & 6)

Item No. Description Qty. Req.

10 Housing 1

19 O-ring 1

20 Drain Plug 1

30 Gear Thrust Flange Bearing 1

40 Bearing Cup 1

50 Gear (144/173 spm) 1

50 Gear (72/86 spm) 1

50 Gear (43/36 spm) 1

50 Gear (180 spm) 1

60 Connecting Rod 1

100 Sliding Crank 1

110 Eccentric 1

120 Shoe 1

130 Retaining Ring 1

140 Ball Bearing 1

150 Retaining Ring 1

160 O-ring 1

171 Stroke Adjustment Screw Assembly 1

175 Stroke Scale 1

190 O-ring 1

200 Side Cover 1

205 Cover Screw (M8 x 16mm) 4

310 Nylon Stroke Locking Ball 1

320 Stroke Locking Knob 1

322 O-ring 1

330 Stroke Adjustment Knob 1

335 Knob Sticker 1

340(note 1) Worm Assembly (173 spm, 56C) 1

Worm Assembly (173 spm, 145TC) 1

Worm Assembly (173 spm, 182TC) 1

Worm Assembly (180 spm, IEC80, F165) 1

343(note 1)

Worm Assembly (144 spm, IEC80, F165) 1

Worm Assembly (86spm, 56C) 1

Worm Assembly (86 spm, 145TC) 1

Worm Assembly (86 spm, 182TC) 1

Worm Assembly (72 spm, IEC 80, F165) 1

26

Instruction Manual

SECTION 6 - PART NUMBERS

Item No. Description Qty. Req.

Worm Assembly (43 spm,56C) 1

343(note 1)

346(note 1)

360(note 1)

370 Oil Fill/Breather Cap 1

376 Motor Adaptor plate (182TC) 1

376 Motor Adaptor plate (IEC80, F165) 1

377 Adaptor plate screws; M10 x 25mm 4

400 Motor screws (182TC);1/2-13 x ¾ 4

400 Motor screws (56C, 145TC); 3/8-16 x 1 4

410 Washer- 56C, 145TC (3/8) 4

450 Base 1

460 Base Screws (M8 x 35mm) 4

465 Lock Washers (8mm) 4

470 Nut (M8) 4

520 Plunger (1-1/4”) 1

520 Plunger (1-3/4”) 1

520 Plunger (2-1/2”) 1

520 Plunger (3”) 1

525 Plunger Pin (1-1/4” plunger) 1

525 Plunger Pin (1-3/4” plunger) 1

525 Plunger Pin (2-1/2”, 3” plungers) 1

560 Lock Washer (8mm) 6

570 Displacement Chamber Screw (M8x30mm) 6

Worm Assembly (43 spm, 145TC) 1

Worm Assembly (43 spm, 182TC) 1

Worm Assembly (36 spm, IEC80, F165) 1

Worm/Motor Coupling (56C) 1

Worm/Motor Coupling (145TC) 1

Worm/Motor Coupling (182TC) 1

Worm/Motor Coupling (IEC80, F165) 1

Spring (182TC) 1

Spring (145TC) 1

Spring (56C) 1

Spring (IEC80) 1

Note 1: Worm Assembly (343) includes worm, coupling (346), spring (360), and bearing cone (340).

Note 2: For part numbers not listed, consult local Milton Roy representative or Milton Roy Aftermarket

Department (215-441-0800).

27Instruction Manual

SECTION 6 - PART NUMBERS

6.2. BASIC PARTS LIST- LIQUID END
(Refer to Figure 7-9)

6.2.1 MARS VALVE (see Figure 9)

Item No. Description Qty. Req.

775(Note 1) Valve Assembly 1

750(Note 2) Valve Body 1

760(Note 2) Poppet 1

770(Note 2) Valve Stem 1

780 Button (1-1/4” plunger) 1

780 Button (1-3/4, 2-1/2, 3” plungers) 1

790 Plug (1-1/4” plunger) 1

790 Plug (1-3/4, 2-1/2, 3” plungers) 1

800 Spring 1

810 Valve Body Retaining Ring 1

820 Valve Stem Retaining Ring 1

830 O-Ring 1

840 O-Ring 1

Note 1: Include items 750, 760, 770, 810, 820, 830, 840.

Note 2: Not sold separately. Must purchase item 775 (MARS Valve Assembly).

6.2.2 REFILL VALVE (see Figure 8)

Item No. Description Qty. Req.

740(Note 1) Rell Valve Assembly 1

650 Oil Strainer Plug, ¼” NPT 1

660(Note 2) Valve Body 1

670 Oil Strainer 1

680(Note 2) Ball 1

690(Note 2) Spring 1

730 O-Ring 1

700(Note 2) Washer 1

710(Note 2) Retaining Ring 1

720 O-Ring 1

Note 1: Includes items 650,660,670,680,690, 700,710,720,730.

Note 2: Not sold separately. Must purchase item 740 (Rell Valve Assembly).

28

Instruction Manual

6.2.3 3- FUNCTION VALVE (see Figure 8)

SECTION 6 - PART NUMBERS

Item No. Description

850 Valve Cap 1

860 Purge Button 1

870 Pin 1

880 Purge Button Spring 1

890 Relief Valve Adjustment Screw 1

900 Relief Valve Locking Nut 1

910 Relief Valve Adjustment Nut 1

920 O-Ring 2

930 Purge Stem 1

935 Washer 1

940 O-Ring 1

950 Relief Valve Spring (1-1/4, 1-3/4” plungers)

PVC Liquid End (purple) 1

Metallic Liquid End (orange) 1

950 Relief Valve Spring (2-1/2, 3” plungers),purple 1

1015(note 1) Poppet Assembly 1

960(note 2) Air Bleed Valve Body 1

970(note 2) Ball 1

980(note 2) O-Ring 1

990(note 2) Air Bleed Ball Seat 1

1000(note 2) Spring 1

1005(note 2) Air Bleed Body Seat 1

Qty.

Req.

Note 1: Includes items 960, 970, 980, 990, 1000, 1005.

Note 2: Not sold separately. Must purchase item 1015 (Poppet Assembly).

6.2.4 CHECK VALVE PARTS (see Figures 10-13)

The Pump Model Number is used to identify the
check valve parts.

The 4 & 5 digits identify the plunger size, digit 6
identies the liquid end material.

MGH -

Digits

• Code 20 is a 1-1/4”(32mm) Plunger

• Code 28 is a 1-3/4”(45mm) Plunger

• Code 40 is a 2-1/2”(63mm) Plunger

• Code 48 is a 3”(75mm) Plunger

• Code 1 is 316SS, Code 2 is PVC, Code 5 is
Alloy 20

4 5 6

Codes for Digits 4 & 5

Codes for Digit 6

29Instruction Manual

SECTION 6 - PART NUMBERS

6.2.5 PVC Liquid End (see Figures 10-13)

1-1/4” plunger: Single Ball Check Valve

(see Figure 12)

Item No. Description Qty. Req.

71 Check Valve Assembly Tubing Conn: includes 2

425 Cartridge Valve Assembly 2

435 Tubing Connector 2

445 Valve Body-Tube 2

71 Check Valve Assembly NPT Conn. includes 2

425 Cartridge Valve Assembly 2

445 Valve Body- NPT 2

4 Function PVC Bleed Valve (see Figure 14)

Item No. Description Qty. Req.

446 ¼” NPT Discharge Bleed Valve Assembly 1

446 ½” Tube Conn. Discharge Bleed Valve Assembly 1

1-1/4” plunger: Double Ball Check Valve

(see Figure 10)

Item No. Description Qty. Req.

425 Check Valve Assembly Assemblies include the following items 1

419 O-Ring, viton 2

420 Ball Stop 1

421 Ball, ceramic, 3/8” 1

422 Ball, ceramic, 14mm 1

424 Ball Guide 1

445 Union End, PVC, ½” NPT Female 1

435 Union Nut, PVC Shown in Figure 11 1

1-3/4”, 2-1/2,” plungers: Double ball check valve

(Figure 10)

Item No. Description Qty. Req.

425 Check Valve Assembly Assemblies include the following items 1

419 O-Ring, viton 2

420 Ball Stop 1

421 Ball, ceramic, 14mm 1

422 Ball, ceramic, 7/8” 1

424 Ball Guide 1

435 Union Nut, PVC Shown in Figure 11 1

445 Union End, PVC, ½” NPT Female 1

30

Instruction Manual

SECTION 6 - PART NUMBERS

1-3/4, 2-1/2, 3” plungers: Single Ball Check
Valves, (Figure 11).

Item No. Description Qty. Req.

425

419 Seal, PTFE Encapsulated Rubber 2

420 Seat, PVDF 1

422 Ball; 5/8” Ceramic 1

423 Seat, Seal, Ball-Replacement Kit 1

424 Ball Guide/Body, PVDF 1

435 Union Nut, PVC 1

445 Union End, PVC, ½” NPT Female 1

6.2.6 Metallic Liquid End (see Figure 10)

316SS & Alloy 20 Liquid End, 1-1/4” Plunger:
Double Ball Check Valve (Figure 13)

Item No. Description Qty. Req.

425 Suction Valve Assembly 316SS 2

425 Suction Valve Assembly Alloy 20 2

426 Discharge Valve Assembly 316SS 2

426 Discharge Valve Assembly Alloy 20 2

Check Valve assemblies include seal (419), seat (420), balls (421), ball guide (424)

435 Lock Nut 2

439 Back- up Ring 2

441 O-Ring, Viton 2

Check Valve Assembly Assemblies include two seals (419), seat (420), ball
(422), ball guide (424)

1

316SS Liquid End, 1-3/4, 2-1/2” plungers:
Double Ball Check Valves

Item No. Description Qty. Req.

425 Check Valve Assembly 1

Check Valve assemblies include two seals (419), seat (420), balls (421, 422), ball guide (424)

419 O-Ring, viton 2

420 Ball Stop 1

421 Ball, 14mm 1

422 Ball, 22mm 1

424 Ball Guide/Body 1

445 Coupling, ½” BSP Female 1

445 Coupling, ½” NPT Female 1

31Instruction Manual

SECTION 6 - PART NUMBERS

Alloy 20 Liquid End, 1-3/4, 2-1/2, 3” plungers:
Double Ball Check Valves (Figure 10)

Item No. Description Qty. Req.

425 Check Valve Assembly 1

Check Valve assemblies include two seals (419), seat (420), balls (421, 422), ball guide (424)

419 O-Ring, viton 2

420 Ball Stop 1

421 Ball, 14mm 1

422 Ball, 22mm 1

424 Ball Guide/Body 1

445 Coupling, ½” BSP Female 1

445 Coupling, ½” NPT Female 1

316SS Liquid End, 3” plungers: Single Ball
Check Valves

Item No. Description Qty. Req.

425 Check Valve Assembly 1

Check Valve assemblies include two O-rings (419), seat (420), ball stop (420), seat (421), ball (422),
body (424)

419 O-Ring, 2

420 Ball Stop 1

421 Seat 1

422 Ball, 22mm 2

424 Body 1

32

Instruction Manual

SECTION 6 - PART NUMBERS

6.3 REMAINING LIQUID END PARTS
(see Figure 8)

Item No. Description Qty. Req.

510 Diaphragm, 1-1/4” 1

510 Diaphragm, 1-3/4, 2-1/2, 3” plungers 1

530 Plunger Sleeve, 1-1/4” plunger 1

530 Plunger Sleeve, 1-3/4” plunger 1

540 O-Ring (1-1/4”, 1-3/4” plungers only) 1

550 Screw, M6 x 18mm (1-1/4, 1-3/4” plungers only) 6

560 Lock Washer 6

570 Screw, M8 x 30mm 6

580 O-Ring 1

590 Gasket 1

600 Displacement Chamber (1-1/4” plunger) 1

600 Displacement Chamber (1-3/4,2-1/2,3” plungers) 1

610 Locating Pin 2

620 Breather Cap 1

630 Sight Glass 2

640 Hose Barb Union 1

650 Displacement Chamber Plug, ¼” NPT 1

1020 Diaphragm Head, PVC, 1-1/4” plunger 1

1020 Diaphragm Head, PVC, 1-3/4,2-1/2,3” plungers 1

1020 Diaphragm Head, 316SS, 1-1/4” plunger 1

1020 Diaphragm Head, 316SS, 1-3/4,2-1/2,3” plungers 1

1020 Diaphragm Head, Alloy 20, 1-1/4” plunger 1

1020 Diaphragm Head, Alloy 20, 1-3/4,2-1/2,3” plungers 1

1025 Head Bolt, Stainless steel

For 1-1/4” plunger sizes: M6 x 55mm 8

For 1-3/4”, 2-1/2” ,3” plunger sizes M12 x 90mm 6

1030 Nut, M12, Stainless Steel (1-3/4,2-1/2,3” plungers) 6

1035 Lock Washer, S.S., M12 (1-3/4,2-1/2,3” plungers) 6

1040 Washer, S.S., M12 (1-3/4,2-1/2,3” plungers) 6

1050 Head Plate (1-1/4”, PVC only); stainless steel 1

33Instruction Manual

Model No. MGH281
Product Code
10CDM2SE11NN22
S/N1234567891
Flow Rate
X.X GPH @ XX PSI
XXX PSI MA WP
Tag No. 12345678
XXXXX12345678

Milton Roy Company
Made in USA

Liquid End C

9”

(228.6 mm)

L

0.354” (9 mm) Dia.
Mounting Holes

Motor

C

L

41/2”

(114.3 mm)

Figure 2. Sample Nameplate

Pressure
Relief
Valve

Figure 3. Mounting Hole Dimensions

Suction

Accumulator

Dampener

Figure 4. Typical Recommended Pump Installation Scheme

34 Instruction Manual

EC80

MOTOR

390

400

56C

182TC

MOTOR

MOTOR

376

410

377

376

417

343

40

346

360

340

370

400

60

520

525

460

465

Figure 5. Drive Parts- Side View

470

450

35Instruction Manual

175

310

160

330

335

171

200

322

320

190

110

10

150

140

205

560

570

130

50

SEE LIQUID END

19

30

20

100

Figure 6. Drive Parts- Top View

36 Instruction Manual

120

1020

PLASTIC ONLY

1050

PLATE IS USED ON 1-1/4” PLUNGER ONLY.
LARGER PLUNGER SIZES USE WASHERS

TORQUE TO

1025

40 IN-LB FOR METALIC
20 IN-LB FOR PLASTIC

View for 1-1/4” PLUNGER Size.

SEE DRIVE HOUSING

1040

610630

630

560

10351030

570

View for 1-3/4”, 2-1/2” and 3 Plunger Sizes.

TORQUE TO
125 IN-LB FOR PLASTIC HEAD

1025

250 IN-LB FOR METAL HEAD

Figure 7. Liquid End- Top View

37Instruction Manual

870

970

980

990

1015

1000

1010

550

TORQUE TO
125 IN-LB

900

1005

530

650

620

950

540

640

880

935

860

850

3- FUNCTION HYDRAULIC VALVE

930

890

920

900

910

920

940

SEE CHECK VALVE

510

1020

720

MARS VALVE
SEE FIGURE

600

590

580

730

740

700710

690

680

670660

650

REFILL VALVE

NEXT SHEET

Figure 8. Liquid End- Section A-A

38 Instruction Manual

MARS VALVE

Mechanically Activated Rell System (MARS) Valve assembly.

Except for O-rings, the valve may only be purchased as an assembly.

810

780

760

830

775

750

770

840

800

Figure 9. MARS VALVE

The MARS Valve is located between the plunger and the diaphragm.

820

790

39Instruction Manual

445

419

420

422

424

421

419

445

DISCHARGE

420

419

422

424

419

SUCTION

PVC and Metallic Double Ball Check Valve Parts- 1-1/4” thru 2-1/2” Plunger Sizes

419

422

420

424

421

Metallic Double Ball Check Valve Parts- 3” Plunger Only

Figure 10.

445

435

419

424

424

422

420

419

DISCHARGE SUCTION

420

419

422

419

435

445

PVC Single Ball Check Valve Parts

Figure 11.

40 Instruction Manual

435

445

425

425

071

445

435

445

425

DISCHARGE

SHOWN WITH TUBE CONNECTIONS

071

DISCHARGE

SUCTION

425

445

SUCTION

SHOWN WITH NPT CONNECTIONS

Figure 12. Plastic Check Valves, 1-1/4” Plunger Size

41Instruction Manual

435

METALLIC CHECK VALVES

437

419

445

426

424

439

441

441

439

435

421

421

421

444

420

421

424

420

425

Figure 13. Metallic Check Valves, 1-1/4” Plunger Size

42 Instruction Manual

PVC LIQUID END FOUR FUNCTION BLEED VALVE 1.25” PLUNGER

FOUR FUNCTION BLEED VALVE
NPT CONNNECTION SHOWN

446

Cartridge Valve Assembly

Cartridge Valve Assembly

425

425

447

SPACER(0.040”)

448

SPACER(0.020”)

Suction Valve Assembly

071

NPT CONNNECTION SHOWN

Figure 14. Four Function Bleed Valve

43Instruction Manual

Ingersoll Rand (NYSE:IR) advances the quality of life by creating comfortable, sustainable and efficient environments. Our people
and our family of brands— including Club Car®, Ingersoll Rand®, Thermo King® and Trane®—work together to enhance the quality
and comfort of air in homes and buildings; transport and protect food and perishables; and increase industrial productivity and
efficiency. We are committed to a world of sustainable progress and enduring results.

[e-mail]
www.miltonroy.com

MILROYAL® is a registered trademark of Milton Roy, LLC.

© 2019 Milton Roy, LLC.