a
®
Model ZW109BP
Pressure Reducing Valve with Low Flow By-Pass
company
SPECIFICATION SUBMITTAL SHEET
APPLICATION
SIZES
GLOBE:
Threaded ends  2" thru 3”
Flanged ends
 2" thru 4”
ANGLE:
Threaded ends  2” thru 3”
Flanged ends
 2" thru 4”
Ductile Iron
 150 Class, 250 psi max.
TEMPERATURE RATING:
 water 33°F to 180°F
BY-PASS and PILOT SPRING RANGE:  15-150 psi
FEATURES
 Epoxy coated, FDA approved
 Pilot Assembly
 Flow clean strainer (sizes 2”-3”)
”Y” type strainer (sizes 4”)
 Opening speed control (sizes 2”-3”)
 Isolation Valve (sizes 4”)
 Low flow by-pass valve uses 1/2” NR3 (sizes 2”, 2 1/2” & 3),
3/4” NR3 (size 4”)
MAIN VALVE OPTIONS
____ Size ____ Y - 300lb. class flange (400 psi max.)
____ TH - Threaded ends (400 psi max.)
____ KB - Viton rubber
____ SS - Stainless Steel Seat
____ AN - Angle body
____ D - Check valve in Pilot
DIMENSIONS
DIM
ANSI CLASS
A
Threaded
AA
150
AAA
300
B
Diameter
C
Max.
D
Threaded
DD
150
DDD
300
E
ALL
F
150
FF
300
G
Threaded (flanged 4")
GG
150
GGG
300
H
NPT Body Tapping
J
NPT Cover Center Plug
K
NPT Cover Tapping
Valve Stem Internal Thread UNF
Stem Travel
Approx. Wt. Lbs.
Page 1 of 2
The Wilkins ZW109BP Pressure Reducing Valve with Low
Flow By-Pass automatically reduces a higher inlet pressure to
a steady lower downstream pressure regardless of changing
flow rate. To be installed in a distribution system where the
demand varies over a wide range. This frequently occurs in
industrial, residential, educational, high-rise buildings and
other applications. Another important feature of the valve is
its space efficient configuration, allowing easy installation
and maintenance.
MATERIALS
Main Valve Body
Main Valve Bonnet
Disc Guide Seat
Disc
Diaphragm
Stem
Spring
Ductile Iron ASTM A536
Ductile Iron ASTM A536
Bronze ASTM B 62
Bronze ASTM B 62
Buna-N Rubber
Nylon reinforced Buna-N
Stainless Steel
Stainless Steel
B (DIAMETER)
J
K
OUTLET
INLET
E
FF F
Valve SIZE inches
2
9 3/8
9 3/8
10
6 5/8
6 1/2
4 3/4
4 3/4
5
1 1/2
3
3 1/4
3 1/4
3 1/4
3 1/2
3/8
1/2
3/8
10-32
0.6
35
2 1/2
11
11
11 5/8
8
7 9/16
5 1/2
5 1/2
5 7/8
1 11/16
3 1/2
3 3/4
4
4
4 5/16
1/2
1/2
1/2
10-32
0.7
50
3
12 1/2
12
13 1/4
9 1/8
8 3/16
6 1/4
6
6 3/8
2 1/16
3 3/4
4 1/8
4 1/2
4
4 3/8
1/2
1/2
1/2
1/4-28
0.8
70
4
15
15 5/8
11 1/2
10 5/8
7 1/2
7 7/8
3 3/16
4 1/2
5
5
5 5/16
3/4
3/4
3/4
1/4-28
1.1
140
C
AA
AAA
A
H
B (DIAMETER)
J
K
C
OUTLET
GGG
GG G
INLET
H
D
DD
DDD
DOCUMENT #: REVISION:
REG-ZW109BP
1/10
WILKINS a Zurn company, 1747 Commerce Way, Paso Robles, CA 93446 Phone:805/238-7100 Fax:805/238-5766
In Canada: ZURN INDUSTRIES LIMITED, 3544 Nashua Dr., Mississauga, Ontario L4V 1L2 Phone:905/405-8272 Fax:905/405-1292
Product Support Help Line: 1-877-BACKFLOW (1-877-222-5356) • Website: http://www.zurn.com
PILOT SYSTEM DIMENSIONS
X
inches
2
2 1/2
3
4
mm
50
65
80
100
X Max. (inches)
12 1/2
12 3/4
13
13 1/4
Y Max. (inches)
4
7
8
9
Z Max. (inches)
6 1/2
8
9
10
Valve
Size
Y
INLET
GLOBE
Z
X
Y
ANGLE
Z
INLET
OPERATION
The Model ZW109BP utilizes a pressure reducing pilot valve that installs on the discharge side of the control circuitry. The pilot is a
direct acting, normally open, spring loaded, diaphragm actuated valve; the spring being adjustable within a 10:1 ratio. The operation
of the ZW109BP begins with accurately sizing the valve, then fine tuning the control circuit by adjusting the NR3 pilot spring to the
desired downstream pressure.
It is hydraulically operated and controlled by a NR3 pilot control, which senses pressure at the main valve outlet. An increase in outlet
pressure opens the control. This causes the main valve cover pressure to vary, modulating the main valve and thereby maintaining
constant outlet pressure. The Model NR3 low flow pressure reducing by-pass is preset to a higher pressure than the pilot control. The
NR3 responds to pressure changes from the main valve outlet. When the pilot control closes, the Model NR3 by-pass valve remains
open allowing water to flow through, by-pass closes when the flow decreases and the downstream pressure reaches its set point.
FLOW CHARACTERISTICS
Valve Size
Suggested
ZW109BP
Flow (GPM)
*Standard ZW109
Suggested Flow
(Liters/sec)
*Suggested extra
By-pass
*Minimum
Flow Rate Range
inches
mm
Max. Continuous
Max. Intermittent
Min. Continuous
Min. Continuous
Max. Continuous
Max. Intermittent
Min. Continuous
Valve sizes
Extra By-pass &
ZW109BP
2
50
210
260
1-10
15
13
16.4
0.9
2 1/2
65
300
370
1-10
20
19
23
0.32
3
80
460
580
1-10
30
29
37
0.32
4
100
800
990
1-20
50
50
62
0.63
1" 500 1-1/4" 500 1-1/2" 500 2" 500
1 - 15
1 to 20
1 to 30
1 to 50
*Adding an extra By-Pass Valve widens the minimum flow range of the ZW109BP to match
the Minimum Continuous flow of the standard ZW109.
OUTLET PRESSURE
GAUGE
INLET PRESSURE
GAUGE
TYPICAL INSTALLATION
Contact the Zurn/Wilkins factory for additional
By-pass recommendations based on your
unique flow applications.
OUTLET SHUT-OFF
INLET SHUT-OFF
DIRECTION OF FLOW
The ZW109BP is not a substitute for a flow
By-Pass in all cases. The valve is commonly
used in buildings where 1-15 GPM low flows
are common in off peak usage. Many Factors
should be considered in sizing a pressure
reducing valve: inlet pressure, outlet pressure
and flow rates. The sizing of additional low
flow by-pass valves are based on a minimum
of a 50 psi differential between the inlet and
set outlet pressure. To develop a smooth
seamless flow response it may be necessary
to add an additional low flow by-pass valve to
the ZW109BP installation to compensate for a
range of anticipated flows below the minimum
continuous flow rate. To control the opening
point of the additional by-pass valves, set the
valve you want to open first 5psi higher in
static downstream set pressure.
NR3
SPECIFICATIONS
The Pressure Reducing Valve shall be a single seated, line pressure operated, diaphragm actuated, pilot controlled, globe or angle
valve. The valve shall seal by means of a corrosion-resistant seat and resilient, rectangular seat disc. These and other parts shall
be replaceable in the field; all such service and adjustments to be possible without removing the valve from the line. The main
valve body shall be ductile iron ASTM A 536. The stem of the basic valve shall be guided top and bottom by integral bushings.
The basic valve and its pilot control system shall contain no packing glands or stuffing boxes. The diaphragm shall not be used
as a seating surface nor shall pistons be used as an operating medium. All internal and external ferrous surfaces shall be coated
with a high quality, fusion epoxy coating. The NR3 pilot control system shall consist of a two-way, normally open, direct acting,
adjustable spring loaded, diaphragm actuated pressure reducing pilot. The pilot control shall be field adjustable from 15 psi to 150
psi; adjustment range not to exceed a 10:1 ratio. The valve shall include a NR3 Pressure Reducing By-Pass Valve. The Pressure
Reducing Valve shall be a WILKINS Model ZW109BP.
JOB NAME
CONTRACTOR
JOB LOCATION
ENGINEER
WILKINS a Zurn company, 1747 Commerce Way, Paso Robles, CA 93446 Phone:805/238-7100 Fax:805/238-5766
IN CANADA: ZURN INDUSTRIES LIMITED, 3544 Nashua Dr., Mississauga, Ontario L4V 1L2 Phone:905/405-8272 Fax:905/405-1292
Product Support Help Line: 1-877-BACKFLOW (1-877-222-5356) • Website: http://www.zurn.com
Page 2 of 2