Milton Roy mROY User manual

mROY®
Pneumatic Capacity Control
Instruction Manual
Manual No. : 53871
Rev. : 01 Rev.
Date : 05/2019

3Instruction Manual
PRECAUTIONS
For Pumps with PVC & 316SS Liquid Ends
WHEN USED IN SWIMMING POOLS OR SPAS/HOT TUBS (ANSI/NSF 50)
Caution on Chemical Concentration:
There is a potential for elevated chemical concentration during periods of no ow, for
example, during backwash in the system. Steps, such as turning the pump off, should be
taken during operation or installation to prevent this. Contact your sales representative or
distributor about other external control options to help mitigate this risk.
Flow Indicating Device:
To ensure operation of the pump it is recommended that some type of ow indicating device
be installed to measure water ow rates and be appropriate for the output of the pump.
Contact your distributor or sales representative for further information.
Head Loss / Over Pressure Protection / Back Pressure-Anti-Siphon Valve:
• Milton Roy metering pumps are positive displacement. Head loss is not applicable to the
pump.
• To ensure safe operation of the pump it is recommended that some type of safety/pressure
relief valve be installed to protect the piping and other system components from failing due
to excessive pressure.
• If you are pumping downhill or into low or no system pressure, a back pressure/anti-siphon
device should be installed to prevent over pumping or siphoning. Contact your distributor or
sales representative for further information.
Additional Operation and Installation Instructions for 316SS or PVC Liquid Ends:
• Application of this pump to swimming pool/spas only evaluated to NSF/ANSI 50.
• There is a potential for elevated chemical concentration during periods of no ow, for
example, during backwash in the system. Steps, such as turning the pump off, should be
taken during operation or installation to prevent this. See your sales representative or
distributor about other external control options to help mitigate this risk.
• Liquid Compatibility CAUTION: Determine if the materials of construction included in the
liquid handling portion of your pump are adequate for the solution (chemical) to be pumped.
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 MSDS precautions from your solution supplier. Reference a
Milton Roy Material Selection Chart for aid in selecting appropriate material of construction
for uids of your specic metering pump. Contact your sales representative or distributor for
further information.

4Instruction Manual
SECTION 1 - PNEUMATIC CAPACITY CONTROL ................................................ 5
SECTION 2 - DISASSEMBLY AND ASSEMBLY PROCEDURE ...................................... 7
2.1 DISASSEMBLY .................................................................. 7
2.2 ASSEMBLY ..................................................................... 7
2.3 CALIBRATION AFTER ASSEMBLY................................................... 7
SECTION 3 - GENERAL PERFORMANCE...................................................... 8
SECTION 4 - OPERATING SPECIFICATION .................................................... 9
SECTION 5 - TABLE OF EQUIVALENTS ...................................................... 11
LIST OF ILLUSTRATIONS
FIGURE 1. Assembly Pneumatic Capacity Control................................................ 10
TABLE OF CONTENTS

5Instruction Manual
Reference the drawing for pneumatic capacity
control assembly and operating principles
(pages 3 and 4) for a schematic and cross section
representation of the pneumatic capacity control
positioner mounted on the mRoy pump. The
assembly consists of three major sections as
follows:
1. The Moore Products Company, Model 73N air
control valve which continuously compares the
location of the piston in the pneumatic cylinder
with the instrument air pressure and regulates
the supply air pressure imposed on one side
of the piston to obtain the required piston
position.
2. The pneumatic cylinder, with a differential area
piston, is the device that moves the capacity
control spool of the pump in response to the
metered supply pressure from the air control
valve. The cylinder is made of a clear impact
resistant plastic, so that the position of the
piston is visible at all times for comparison
against a “Percent Capacity” decal. (Read
percent capacity at the black line of the O-ring
contact).
3. The mounting ange, which is used to rigidly
mount the assembly onto the standard
production mRoy pump assembly, forms the
end of the pneumatic cylinder and seals off the
I.D. of the piston to establish a differential area
between the two sides of the piston.
At time of installation, the instrument air pressure
(Pi) and the supply air pressure (Ps) are connected
to the corresponding ttings in the air control valve.
The supply air (Ps) is routed internally to the pilot
valve and it is also routed unrestricted, internally
through the cylinder wall onto the small area (pump
side) of the differential area piston. The instrument
air pressure (Pi) is routed to a “dead end” cavity
formed by the exible diaphragm assembly.
As shown by the schematic, the supply pressure
imposed on the small area side of the piston
creates a force to move the piston until it bears
against, and compresses, the range spring. The
range spring in turn is supported by the exible
diaphragm assembly which bears against the stiff
suppression spring. The diaphragm assembly is
then a moveable element between two opposing
spring forces. This movement of the diaphragm
assembly is transmitted to the pilot valve which
acts to either increase or decrease the metered
supply air pressure (Psm) imposed on the large
area side of the piston. The relationship of metered
supply pressure (Psm) on one side and full supply
pressure (Ps) on the other side of the differentially
area piston is used to establish and maintain the
required capacity control position. A xed air bleed
is incorporated in the metered supply ‘pressure
chamber which will maintain a small air ow across
the pilot valve to provide instant response to any
changes in the operating conditions.
SECTION 1 - PNEUMATIC CAPACITY CONTROL

6Instruction Manual
SECTION 1 - PNEUMATIC CAPACITY CONTROL
In operation, an increase in instrument air pressure
(Pi) upsets the balanced forces and moves the
diaphragm assembly to the left. This lifts the pilot
valve above its seat to reduce the air pressure drop
across the pilot valve and increases the metered
supply pressure, (Psm) on the downstream side
of the pilot valve, which is imposed on the large
side of the air piston. The metered supply pressure
will continue to increase until sufcient force is
developed to move the piston to the right which
increases the pump capacity.
As the piston moves, the range spring feeds back
a force proportional to the piston location so that
when the range spring pressure plus the diaphragm
force from the instrument air signal are again in
balance with the suppression spring force, the pilot
valve closes and maintains a balanced pressure
condition.
A decrease in instrument air pressure moves the
diaphragm assembly to the right which seats the
head of the pilot valve and lifts the pilot valve stem
off the exhaust seat. This vents the pressure (Psm)
on the large side of the piston at atmosphere (Pa),
then the supply pressure on the small side of the
piston will move the piston to the left to decrease
the pump capacity. Again the range spring feeds
back to the positioner the location of the air piston
until the forces are again in the balanced condition.

7Instruction Manual
SECTION 2 - DISASSEMBLY AND ASSEMBLY PROCEDURE
2.1 DISASSEMBLY
1. Disconnect the supply and instrument air
pressure lines.
2. Remove the six ¼ -20 NC nuts from the air
control valve hold-down studs.
3. Mark the alignment between the air control
valve, gasket, cylinder and mounting ange to
facilitate reassembly.
4. Remove positioner by sliding off hold-down
studs.
5. Remove spring adapter plate and spring from
bore of cylinder.
6. Slide plastic cylinder off mounting studs to
expose piston.
7. Hold piston O.D. and remove mounting screw
in center of piston.
8. Remove the mounting screw in the ange and
the screw in the barrel of the ange. Now slide
the ange off the pump capacity control boss.
9. Use a thin screwdriver or similar tool to remove
“E” ring which retains the piston adapter onto
the pump capacity control spool.
This completes the disassembly.
2.2 ASSEMBLY
For assembly follow the disassembly procedure in
reverse order (descending step numbers from
9 to 1) making certain that the O-rings are lubricated
with pump oil or ring lubricant before assembly of
the retaining part. Make certain that parts are
aligned in the same way as the original assembly.
Make certain the gasket between the Moore
positioner and the cylinder body is positioned so
that the small hole in the gasket, adjacent to the
stud hole, is aligned with the corresponding hole
through the plastic cylinder.
2.3 CALIBRATION AFTER ASSEMBLY
To calibrate the pneumatic capacity control
after reassembly, apply an instrument air signal
corresponding to 100% capacity setting. Remove
the cover on the top of the valve positioner and use
a screwdriver to turn the zero adjust until the piston
seal line corresponds to the 100% graduation on
the % capacity decal. Turn the adjusting screw
counter clockwise to move the piston away from
the pump.

8Instruction Manual
SECTION 3 - GENERAL PERFORMANCE
The pneumatic capacity control assembly will
provide accurate incremental adjustment in both
directions as a linear function of the applied
instrument air pressure. There is no tendency for
the capacity control to “drift” off setting over long
periods of time because
1. There is no signicant force acting on the pump
capacity control adjustment spool.
2. The friction from, the sealing rings act to hold
the spool in position until the pneumatic capacity
control applies sufcient force to overcome this
friction.
With 40 psi supply air pressure, the pneumatic
capacity control cylinder will develop up to 40
pounds force in the direction to increase the
capacity setting and up to 110 pounds force
in the opposite direction. Then with 100 psi air
pressure applied, these forces are increased to
100 pounds and 275 pounds respectively. There is
no noticeable change in control position when the
supply air pressure is varied within the specied
pressure range. However, the nominal force
required to overcome the seal ring friction on the
control spool is in the range of 17-30 pounds, so
the pneumatic capacity control should have no
difculty providing rapid, accurate adjustment of
the pump capacity when the minimum specied
control air pressure is applied.
It should be noted that the instrument air pressure
is applied to a closed chamber in the positioner
valve so that the regulator or instrument system
establishing the air signal must incorporate a
venting air bleed to insure accurate air signal
response.

9Instruction Manual
SECTION4-OPERATINGSPECIFICATIONS
Supply Pressure Regulated 40-100 psi.
CDA (Instrument) Pressure Range 3-15 psi standard, other pressure ranges available on
special order.
Pump Capacity Variation over Instrument
Pressure Range 0-100% rated capacity.
Minimum Pressure Change Required to Reset
Capacity 0.20 psi or 0.13% of full range pressure.
Linearity of Actuator Movement
Within 5% of maximum capacity (maximum difference
in output between calibration curve and most favorable
straight line drawn through curve).
Repeatable Accuracy of Actuator Position
Within 1% of full stroke. (Maximum difference between
two positions of output for the same value of input
always approached from one direction)
Supply Air Consumption (Balanced Condition) 0.2 - 0.4 SCFM
Instrument Air Consumption 0 SCFM
Failure to Supply Pressure (Ps) Moves to 100% position.
Failure of Instrument Air (PI) Moves to 0% position.

10 Instruction Manual
1010
1000
220
980
1070
1100
1020
1050 1090
1040
990
215
1060 1080
1130
1110
1120
1140
1030
150
1145
- (ACTUATOR)
ITEM NO. DESCRIPTION
0MROY PCC INSTRUCTION MANUAL
220CLIP 1/4 E-RING EXTERNAL
150PLUG 1 NPT LVLSL HEXS 18-8SS
150PLUG 1/2 NPT LVLSL HEXS 18-8SS
215ADAPTER
980MOUNT FLANGE MROY A PNEU.
990O-RING .921 X .139 BUNA N
1000INT TOOTH LOCK WASHER #6 Z PL
1010RD HD SCR #6-32NCX7/16 Z PLT
10205/16-18 SLOTTED SHOULDER SCREW
1030O-RING#2-011 70 DURO URETHANE
1040PISTON
1050O-RING 2-226 BUNA N
1060FIL HD SCR 1/4-20X1/2 ZPL
1070GASKET, PNEUMATIC CYLINDER
1080PNEUMATIC CYLINDER POLYCARBONA
1090SPRING, ACT SH -P/N 6240-23
1100GASKET PNEUMATIC POSITIONER
1110STUD
1120MOORE POSTIONER MODEL 73N12F
1140PNEUMATIC % CAPACITY DECAL RA
11301/4-20 HEX NUT SS
Figure 1. Assembly Pneumatic Capacity Control (102197100015)

11Instruction Manual
SECTION 5 - TABLE OF EQUIVALENTS
1 atmosphere Equals
1.0333 kilograms/square centimeter
101.33 kilopascals
1.0135 bars
1 Btu/hour Equals 0.2928 Watts
Degrees Fahrenheit Equals 1.8° Celsius + 32
1 Engler degree Equals 7.45 square millimeters/second
1 foot Equals 30.48 centimeters
12 inches
1 Ford cup #4 Equals 3.76 square millimeters/second
1 gallon (U.S.) Equals
0.1337 cubic feet
0.8333 Imperial gallons
3.785 liters
4 quarts
1 gallon/hour (U.S.) Equals 0.003785 cubic meters/hour
0.002228 cubic feet/minute
1 horsepower Equals 745.7 Watts
1 inch Equals 2.540 centimeters
1 inch of mercury Equals
0.03442 kilograms/square centimeter
3376.5 Pascals
0.4897 pounds/square inch
1 pint (liquid) Equals 0.4732 liters
16 ounces
1 pound/square inch Equals
0.06804 atmospheres
0.06897 bars
0.07029 kilograms/square centimeter
6894.8 Pascals
1 Redwood Admiralty Equals 2.340 square millimeters/second
1 Redwood Standard Equals 0.237 square millimeters/second
1 Saybolt Furol Equals 2.16 square millimeters/second
1 Saybolt Second Universal Equals 0.216 square millimeters/second

MROY® is a registered trademark of Milton Roy, LLC.
© 2019 Milton Roy, LLC.
[e-mail]
www.miltonroy.com
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