Watts LF919 User Manual
Installation, Maintenance, & Repair
Series 919 and LF919
Reduced Pressure Zone Assemblies
Sizes: 1⁄4" – 2" (8 – 50mm)
RP/IS-919
919QT
WARNING
!
You are required to thoroughly read all installation instructions
and product safety information before beginning the installation of this product. FAILURE TO COMPLY WITH PROPER
INSTALLATION AND MAINTENANCE INSTRUCTIONS
COULD RESULT IN PRODUCT FAILURE WHICH CAN
CAUSE PROPERTY DAMAGE, PERSONAL INJURY AND/
OR DEATH. Watts is not responsible for damages resulting
from improper installation and/or maintenance.
Local building or plumbing codes may require modifications to
the information provided. You are required to consult the local
building and plumbing codes prior to installation. If this information is not consistent with local building or plumbing codes, the
local codes should be followed.
Need for Periodic Inspection/Maintenance: This product
must be tested periodically in compliance with local codes, but
at least once per year or more as service conditions warrant.
Corrosive water conditions, and/or unauthorized adjustments
or repair could render the product ineffective for the service intended. Regular checking and cleaning of the product’s internal
components helps assure maximum life and proper product
function.
NOTE: For Australia and New Zealand, line strainers should be
installed between the upstream shutoff valve and the inlet of the
backflow preventer.
Its important that this assembly be tested periodically in compliance with local codes, but at least once per year or more as
service conditions warrant. If installed on a fire sprinkler system, all
mechanical checks, such as alarm checks and backflow preventers, should be flow tested and inspected internally in accordance
with NFPA 13 and NFPA 25.
Testing
For field testing procedure, send for IS-TK-DL, IS-TK-7,
IS-TK-9A, IS-TK-99E AND IS-TK-99D.
For other repair kits and service parts, send for PL-RP-BPD.
For technical assistance, contact your local Watts
representative.
Installation Instructions
Series 919 and LF919
1
⁄4" – 2" (8 – 50mm)
Indoor Installation
Reduced Pressure Zone Assemblies
Indoor Installation
For indoor installations, make sure the Series 919 and LF919 is
easily accessible to facilitate testing and servicing. Do not install in
concealed locations. If the location of the Series 919 and LF919
is parallel and close to the wall, make sure the test cocks are easily accessible, and the drain line can adequately drain if required.
An air gap and drain line (see literature ES-AG/EL/TC) are piped
from the relief valve connection as shown, allowing evidence of
discharge to be clearly visible and preventing the occurrence of
water damage.
Outdoor, Above Ground Installation
For outdoor installations, it is recommended that you install the
Series 919 and LF919 where there are no freezing conditions and
above ground whenever possible.
You must install the Series 919 and LF919 in an accessible location to facilitate testing and servicing. The installation must also
allow for adequate drainage from the air gap and the discharge
line if needed.
WARNING:
1. Do not allow the drain line to empty directly into a drainage
ditch, sewer system, or sump.
2. Do not install the Series 919 and LF919 in any location where
any part of the unit could become submerged in standing
water.
Watts
1
⁄4" – 2" (8 – 50mm) 919
Meter
Strainer
12" (300mm) Minimum
(refer to local codes)
Outdoor Installation
FIBERGLASS WattsBox
1
(8 – 50mm)
919AQT
Min. 12" (300mm)
Min. 12"
Now available, Wa ttsBox Insulated Enclosures,
for more information, send for literature ES-WB.
Air Gap
Watts
⁄4" – 2"
Parallel Installation
For parallel installations, you can install two or more small sized
Series 919's and LF919's (when approved) to serve a large supply
pipe main. You can use this type of installation in an application
where increased capacity beyond that provided by a single valve
is required. Additionally, this type of installation permits testing
and/or servicing of a single valve without shutting down the complete line.
The number of Series 919 and LF919 units installed in parallel
should be determined by the engineer's judgement, based on the
operating conditions of a specific application.
NOTE: The total capacity of all the units installed in the application
should equal or exceed that required by the system.
Annual inspection of all water system safety and control valves
is required and necessary. Regular inspection, testing and
cleaning assures maximum life and proper product function.
2
Parallel Installation
Watts
1
⁄4" – 2" 919
(8 – 50mm)
Installation Instructions
1/2"
3/4" M2
1" M2
Series 919 and LF919
1
⁄4" – 2" (8 – 50mm)
A. Shutoff Valves: If you remove the shutoff valves from the Series 919 and LF919, reassemble
the shutoff valve with the test cock mounted on the inlet side of the unit.
B. Always install the Series 919 and LF919 in an accessible location to facilitate testing and
servicing (See Page 2). *Check the state and local codes to ensure that you install
the backflow preventer in compliance with those codes, such as the proper height
above the ground.
C. It is recommended that you install a strainer ahead of the Series 919 assemblies to protect
the internal components from unnecessary fouling.
CAUTION:
Do not install a Series 919 and LF919 with a strainer in rarely used water lines, such as a fire
sprinkler system which is only used during emergencies.
Start Up: Close the downstream shutoff. Open the upstream slowly and fill the valve. When the
valve is filled, open the downstream shutoff slowly, and fill the water supply system. This is necessary to avoid water hammer and/or shock damage.
D. Vent the air gap and drain line from the relief valve in accordance with code requirements.
Terminate discharge approximately 12" (300mm) above the ground or through an air gap
piped to a floor drain.
WARNING:
Do not allow the drain line to empty directly into a drainage ditch, sewer system, or sump.
NOTE: Relief Valve Discharge Rates
The Series 919 and LF919 air gap and drain line terminating above a floor drain
can accommodate any moderate discharge or nuisance spitting through the
relief valve. However, to prevent water damage in the case of a catastrophic failure, you may need to design the floor drain size to accommodate the increased
discharge. Refer to Figure 1 for maximum relief valve discharge rates, size, and
capacity of typical floor drains.
NOTE: DO NOT reduce the size of the drain line from the air gap fitting. The drain
line must remain at full line size.
E. After initial installation of the Series 919 and LF919, a discharge from the relief
valve may occur due to dirt and pipe compounds. This may be due to inadequate initial flushing of the pipe lines. If flushing the valve does not clear the
unit, remove the first check valve and clean thoroughly, using the procedures
in "Servicing First & Second Check Valves" on page 6.
NOTE: Periodic relief valve discharge may occur on dead end service applications,
such as boiler feed lines or cooling tower makeup lines. This may be due to fluctuating
supply pressure during a static or no flow condition. To avoid this discharge, install a
spring-loaded, rubber seated check valve ahead of the backflow assembly.
F. It is recommended that you not place the Series 919 and LF919 in a pit or at
a depth below the ground level, unless absolutely necessary. If an installation
requires below ground level installation, a modified pit installation is recommended, as well as the approval of local codes. In such cases, provision
should be made to always vent the drain line above the flood level. In the
case of a pit drain, ensure an adequate air gap exists between the bottom of
the drain line and the bottom of the pit.
G. It is recommended that periodic inspection of the Series 919 and LF919 be
done to check for any discharge from the relief valve. This discharge is a
visual indication that the valve needs cleaning or repair. In addition, it is recommended that periodic testing of the valve be done in compliance with local
codes to ensure its proper operation.
The relief vent discharges water during no-flow periods when:
(1) the first check valve is fouled; or
(2) the inlet pressure to the check valve drops sufficiently due to upstream pres-
sure fluctuations. This affects the required operating differential between the
inlet pressure and the reduced pressure zone; or
(3) the second check is fouled during emergency backflow or resulting from a
water hammer condition.
For troubleshooting guide send for literature S-TSG.
NOTE: When installing the Series 919 and LF919 on fire prevention systems,
special considerations are required.
Fire Protection System Installations: The National Fire Protection Agency (NFPA)
Guidelines require a confirming flow test be conducted by a certified tester whenever a “main line” valve is installed, such as a shutoff valve or a backflow preventer.
45
40
35
30
25
20
15
Flow Rate gpm
10
5
0
0 10 20 30 40 50 60 70 80 90 100 110
(8 – 15mm) (20mm) (25mm)
350
300
250
200
150
100
Flow Rate gpm
50
0
0 10 20 30 40 50 60 70 80 90 100 110
Typical Flow Rates as sized by floor drain manufacturers:
2" 55 GPM 5" 350 GPM
3" 112 GPM 6" 450 GPM
4" 170 GPM 8" 760 GPM
Figure 1
1
⁄4" – 2" 919
Watts
*Vertical Flow Down
Strainer
Elbow
Air
Gap
Floor Drain
1
⁄4" – 1" (8 – 25mm) 919 and LF919
1
⁄4"–1⁄2" c 3⁄4" X 1"
1
1
Zone Pressure psi
⁄4" – 2" (32 – 50mm) 919 and LF919
Zone Pressure psi
0 11⁄4"–11⁄2" 2"
(32 – 40mm) (50mm)
3
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