Milton Roy H Series User manual

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

3
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

4
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

5
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

6
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

7
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.

8
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

9
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.

10
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

11
Safety
Valve
Metering
Pump
To high
pressure
service
Self draining
line to catch
basin or
supply tank
Pressure
Gauge
INSTALLATION
Safety Valves (Refer to Figure 5)
Generally, a safety valve should be installed as near
as possible to the discharge port of the pump which the
valve is to protect. The valve should always be installed
upstream of any shut off valve in the discharge line in or-
der to protect the pump if a shut off valve should be in-
advertently closed while the pump is in operation. Since
the Milton Roy safety valve is a diaphragm type, the valve
must be installed so that no back pressure can be applied to
the outlet*. This means that the valve must be installed in
Figure 3. Safety Valve Installation.
With a safety valve connected as shown, the pressure
setting can be changed or the internal parts can be
replaced without removing the valve from the line.

12
such a way that it will be self-draining after operation.
NOTE:
The presence of any small pressure on the outlet
can cause valve chattering and variations of actu-
ating pressure. Even a few feet of standing liquid
pressure on the outlet can cause unwanted valve
operation.
Satisfactory ways of piping the outlet include: (1)
directly to a drain, with the piping properly sloped
downward from valve to drain, and (2) back to the
chemical storage tank, with the valve outlet at the
top of the storage tank and piping extending into it.
The Milton Roy diaphragm safety valve should not
be used: (1) on liqueed gas applications where the
outlet cannot be opened to the atmosphere, (2) on
any application where the outlet may be subjected to
uid pressure, (3) across a pump, that is, the valve
should never be connected from the discharge side
of a pump to the suction side of the pump.
CAUTION:
Be sure to install safety valves so that the inlet
port at the bottom is connected to the system to be
protected from overpressure. Outlet pressure over
100 psi exceeds the valve burst pressure rating.

13
Back Pressure Valve (Refer to Figure 6)
Generally, a back pressure valve should be in-
stalled on the discharge line of the pump if the natural
pressure in the pipe line is lower then the minimum
allowable discharge pressure for the pump. This is
usually about 50 psi. The valve should be installed
near the pump. However, on some systems, it may
be necessary to locate the back pressure valve near
the point where the liquid enters the process. This
situation often occurs when the discharge line is
small in diameter and very long.
Safety
Valve Pulsation
Dampener
Back Pressure
Valve
Metering
Pump To low
pressure
service
Self draining
line to catch
basin or
supply tank
Pressure
Gauge
Pressure
Gauge
Figure 4. Back Pressure Valve Installation.
For maximum safety, piping for back pressure valves
should include a safety valve as close to the pump as
possible.

14
The performance of a back pressure valve can be
aided by the use of a pulsation dampener or surge
chamber between the pump discharge and the back
pressure valve (refer to Figure 4). The pulsation damp-
ener will absorb the peak ow from the pump, allowing
the valve to operate at an average opening. In this way,
the valve will not have to open on the pump discharge
stroke and close at the end of the stroke. Thus, the dia-
phragm will stay open at an average position, not wide
open nor tightly closed. A pulsation dampener will not
only greatly reduce the wear on the moving parts of the
valve, but will also cause the ow of the process liquid
to be more nearly continuous instead of pulsating.
It is suggested that some form of standard com-
mercial hydraulic accumulator or pulsation dampener
be considered in these applications. Contact Milton
Roy Company for information on AccuRoy™ Pulsation
Dampeners.
NOTE:
The Milton Roy back pressure valve should not be
used in abrasive slurry applications because the slur-
ry will quickly erode the seat and disable the valve.

15
START-UP
Before starting a system with a Milton Roy safety or
back pressure valve installed, make sure that the valve
is set to the proper pressure for the application. The
factory set pressure is stamped on the valve name-
plate. If a pressure other than the factory set pressure
is desired, refer to “Adjusting Set Pressure” below.
Make sure that the valve is properly piped, with the
valve in the proper position. Inlet and outlets are indi-
cated in Figures 5 & 6.
Adjusting Set Pressure (refer to Figures 5 & 6)
The set pressure of Milton Roy safety and back pres-
sure valves can be adjusted within the range specied
by the model code. It should never be adjusted outside
of this range as improper operation and/or damage to
the valve and/or other system components may occur.
Back Pressure Valve Pressure Setting
The valve pressure should be set with the valve
installed and with the pump operating. With a pres-
sure gauge installed between the pump and the valve,
adjust the valve adjusting screw (N) until the desired
pressure is read on the gauge.
SECTION 3
OPERATION

16
Safety Valve Pressure Setting
CAUTION:
This procedure should be performed only by
trained, competent personnel. It involves actions
which, if not performed correctly, could result in
serious personal injury from piping and equipment
bursting (from being subjected to pressure great-
er than 5000 psi) and sudden release of process
chemical.
Unless local requirements conict, it is recom-
mended that the safety valve set pressure be 20%
or more greater than the highest expected operat-
ing pressure, but under no circumstance should it
be greater than the maximum pressure rating of the
lowest pressure rated item in the hydraulic circuit
(valves, pressure gauges, pipe, pipe ttings, pump,
etc.).
Setting Methods
There are two methods commonly used, “bench”
and “in place.”
1. Bench setting procedures are established by the
setting facility.
2. In place setting is setting the relieving pressure
while the valve and pump are installed and operat-
ing in the working application. To do this:

17
a. Install a shut off valve in the pump discharge
line downstream of the safety valve.
b. Install a pressure gauge between the safety
valve and the pump. The gauge should have
a maximum pressure at least 30% higher than
the safety valve setting.
c. With the shut off valve open, operate the pump
at the maximum expected ow rate setting.
d. Use a hex key tool to adjust the safety valve
setting to its lowest setting, which is when the
adjusting screw (N) is ush with the top of the
body.
e. While observing the pressure gauge, slowly in-
crease pressure in the pipeline by slowly clos-
ing the shut off valve. Don’t close it all the way.
f. At some point, the safety valve should begin
relieving. Continue closing the shut off valve to
completely closed while observing the pressure
gauge. (The pressure gauge should not regis-
ter a pressure higher than your intended set
pressure. If it does, immediately open shut off
valve and make sure that step 2d was properly
followed and that the valve is large enough for
the system it is relieving. Do not allow pressure
to rise above intended set pressure.)
g. Adjust the set pressure of the valve with the
hex key until the desired pressure is read on

18
the gauge.
h. Open the shut-off valve and turn off the pump.
i. Check the relief valve setting by operating the
pump with the shut-off valve open. Slowly close
the shut-off valve. The relief valve should open
at the previously set pressure. Readjust the re-
lief valve as necessary.
NOTE
Pressure setting changes should be made only af-
ter careful consideration of the effect of the change
on the entire hydraulic system, including the con-
trolled volume pump. Never attempt to adjust the
valve outside of the pressure limit shown in the
model code, as improper operation and/or dam-
age to the valve and/or other system components
may occur.

19
RECOMMENDED SPARE PARTS
It is recommended that a standard spare parts
group be kept on hand at all times to prevent serious
delay in repairs.
Safety Valves Back Pressure Valves
1 Diaphragm (50) 1 Diaphragm (50)
1 Ball (80) 1 Control Seat (30)
1 Ball Seat (30) 1 Gasket (20)
1 Ball Guide (40) 1 Gasket (90)
1 Gasket (20)
1 Gasket (90)
Part orders must include the following information:
1. Quantity required.
2. Part number.
3. Part description.
4. Valve serial number (on valve nameplate).
5. Valve model number (on valve nameplate).
Always include the serial and model numbers in
all correspondence regarding the unit.
All inquiries or parts orders should be addressed
to your local Milton Roy Representative or sent to:
SECTION 4
MAINTENANCE

20
Milton Roy Company
201 Ivyland Road
Ivyland, PA 18974-0577
Phone [phone]
FAX [phone]
www.miltonroy.com
[e-mail]
Terms and conditions are listed below:
a. Terms are net 30 days, f.o.b. factory. Transporta-
tion charges are collect, unless otherwise noted.
b. All shipments are made at the purchaser’s risk,
FOB Ivyland. Any claims for damage or nondeliv-
ery should be led with the carrier at the destina-
tion. We will be glad to assist in providing shipping
information.
c. Where obsolete parts are ordered, we reserve the
right to furnish the latest interchangeable part.
d. No credit for returned material will be allowed un-
less authorization has rst been obtained from
the factory. Such shipment must be prepaid and
include a Milton Roy Return Material Tag.
RETURNING UNITS TO THE FACTORY
Milton Roy valves will not be accepted for repair
without a Return Material Authorization, available from
the Factory Repair Department. The valve should be