Milton Roy H Series User manual

H Series
Safety & Back Pressure
Valves
INSTRUCTION
MANUAL
339-0023-000
Issued 4/2011

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TABLE OF CONTENTS
Warranty . . . . . . . . . . . . . . .visit www.miltonroy.com
Section 1 Introduction ............................. 6
Description ............................. 6
Product Coding ......................... 7
Principle of Operation ................... 8
Section 2 Installation .............................10
Unpacking .............................10
Safety Precautions .....................10
Installation ............................. 11
Section 3 Operation ..............................15
Start-Up ...............................15
Adjusting Set Pressure ................15
Section 4 Maintenance ...........................19
Recommended Spare Parts . . . . . . . . . 19
Returning Units to the Factory ..........20
Maintenance ...........................21

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TABLE OF CONTENTS (Continued)
Section 5 Troubleshooting .......................23
Back Pressure Valves .................. 23
SafetyValve ..................... 24
Section 6 Parts ..................................25
1/2” Safety Valve Parts List .............26
1” Safety Valve Parts List ..............28
1/2” Back Pressure Valve Parts List . . . . 30
1” Back Pressure Valve Parts List . . . . . . 31

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LIST OF ILLUSTRATIONS
Figure 1. Safety & Back Pressure Valves ........... 6
Figure 2. Product Code . . . . . . . . . . . . . . . . . . . . . . . . 7
Figure 3. Safety Valve Installation ................11
Figure 4. Back Pressure Valve Installation ......... 13
Figure 5. Safety Valve Parts Drawing ............. 25
Figure 6. Back Pressure Valve Parts Drawing . . . . . . 29

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Section 1
Introduction
DESCRIPTION
Milton Roy diaphragm safety valves are designed
primarily to protect controlled volume pumps and asso-
ciated equipment from overpressure. Milton Roy back
pressure valves are engineered to ensure the neces-
sary differential back pressure on controlled volume
pumps in specic situations.
Outwardly, Milton Roy chemical safety valves and
back pressure valves appear identical except for ar-
rows indicating inlet and outlet connections; however,
the two valves differ internally (refer to Figures 5 and 6).
The safety valve has a diaphragm, ball and ball guide.
The back pressure valve
on the other hand, does
not use a ball because its
diaphragm seats directly
on the valve seat.
The inlet connection
for the safety valve is at
the bottom with the outlet
connection on the side.
For back pressure valves
with a set pressure of
70 psi or below, the inlet
connection is on the side,
and the outlet connection
is at the bottom. For back
pressure valves with 71
psi and higher set pres-
Figure 1. Safety & Back
Pressure Valves are
outwardly identical

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V
Valve Type Size Material of
Construction
1 = 316 SS
5 = Alloy 20
S = Safety
B = Back Press.
08 =1/2"
16 =1"
Set Pressure Range
Safety Valves
1"
2 = 20-375
3 = 376-1000
1/2"
2 = 20-49
4 = 50-300
5 = 301-600
6 = 601-1200
7 = 1201-1500
Back Press. Valves
1"
2 = 5-35
3 = 36-70
4 = 71-125
5 = 126-200
1/2"
2 = 5-35
3 = 36-70
4 = 71-100
5 = 101-200
sure, the inlet connection is on the bottom, and the
outlet connectionion is on the side.
NOTE:
A safety valve cannot be changed to back pressure
service by simply reversing the connections.
PRODUCT CODING
Milton Roy safety and back pressure valves are
available in several different congurations. To deter-
Figure 2. Product Code.

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mine which features a specic valve has, compare the
product code shown on the valve nameplate with Figure
2. The nameplate is located on the upper body of the
valve.
PRINCIPLE OF OPERATION
Safety Valves (refer to Figure 5)
The Milton Roy Safety Valve operates on a differen-
tial area principle. The inlet pressure acts against the
ball, and the resulting force is opposed by the spring.
Product Coding
Milton Roy safety and back pressure valves are
available in several different congurations. To deter-
mine which features a specic valve Whenever the inlet
pressure exceeds the set pressure, the ball rises from
the seat. Consequently, a ow of liquid passes through
the valve. After the pressure in the system drops to the
point where the force on the diaphragm is insufcient to
hold it open, the valve closes.
Back Pressure Valves (refer to Figure 6)
The Milton Roy Back Pressure Valve maintains a
set pressure at the metering pump discharge to insure
precise metering and to prevent siphoning* in systems
where process pressure is lower than suction pressure.
During the pump discharge stroke, pressure acts on the
valve diaphragm, lifting it off the back pressure seat and

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allowing the metered volume of liquid to ow through
it. As the pump discharge ow decreases to zero (suc-
tion stroke), the diaphragm reseats and traps the liq-
uid under pressure between the pump outlet and the
valve. This maintains a constant positive pressure on
the pump discharge check valve.
Note:
*Siphoning is prevented only when the pump is
producing ow. With the pump turned off, liquid
may leak through the valve. If positive siphon
shut off is required when the pump ow is at zero,
a positive shut off valve should be employed.

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UNPACKING
Units are shipped FOB factory and the title passes
to the customer when the carrier signs for receipt of the
unit. 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 dam-
aged or lost. Examine all material inside the crate and
check against the packing list to be sure that all items
are accounted for and intact.
SAFETY PRECAUTIONS
When installing, operating, and maintaining safety
and/or back pressure valves, keep safety consider-
ations 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 pres-
ence of hazardous substances (e.g., corrosives, toxics,
solvents, acids, caustics, ammables, etc.).
SECTION 2
INSTALLATION