Watts 957Z User Manual
Installation, Maintenance, & Repair
Series 957, 957RPDA, LF957RPDA
Reduced Pressure Zone Assemblies
Reduced Pressure Detector Assemblies
Sizes: 21⁄2" – 10" (65 – 250mm)
!
WARNING
Read this Manual BEFORE using this equipment.
Failure to read and follow all safety and use information
can result in death, serious personal injury, property
damage, or damage to the equipment.
Keep this Manual for future reference.
RP/IS-957/957RPDA
Local building or plumbing codes may require modifi cations 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.
NOTICE
For Australia and New Zealand: Pipeline strainers should be
installed between the upstream shutoff valve and the inlet of the
backflow preventer.
It's important that this device 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, refer to Watts installation sheets
IS-TK-DP/DL, IS-TK-9A, IS-TK-99E and IS-TK-99D found on
www.watts.com.
For other repair kits and service parts, refer to our Backflow Prevention Products Repair Kits & Service Parts price list
PL-RP-BPD found on www.watts.com.
For technical assistance, contact your local Watts representative.
957 OSY
Installation Instructions
Series 957, 957RPDA, LF957RPDA
Guidelines
1. Most field problems occur because dirt and debris are present in the system at the time of installation and becomes
trapped in the #1 check. The system should be flushed
before the backflow valve is installed. If the system is not
flushed until after the backflow valve is installed, remove both
check modules from the valve and open the inlet shutoff to
allow water to flow for a sufficient time to flush debris from
the water line. If debris in the water system continues to
cause fouling, a strainer can be installed upstream of the
backflow assembly.
2. Watts Series 957, 957RPDA and LF957RPDA may be installed in either horizontal, “N” pattern, or “Z” pattern position
as long as the backflow assembly is installed in accordance
with the direction of the flow arrow on the assembly and the
local water authority approves the installation.
3. The assembly should be installed with adequate clearance
around the valve to allow for inspection, testing and servicing. 12" (305mm) should be the minimum clearance between
the lower portion of the assembly and the floor or grade. The
valve should be protected from freezing.
4. Installing a backflow preventer in a pit or vault is not recommended.
5. Normal discharge and nuisance spitting are accommodated
by the use of a Watts air gap fitting and a fabricated indirect
waste line. Floor drains of the same size must be provided in
case of excessive discharge.
6. The 957, 957RPDA and LF957RPDA backflow preventer
should be tested by a certified tester at the time of installation.
NOTICE
Assembly body should not be painted.
Installation Instructions
Series 957, 957RPDA, LF957RPDA
Horizontal Installation
N Pattern
Z Pattern
Maintenance
Instructions
Series 957, 957RPDA,
LF957RPDA
21⁄2" – 6" (65 – 150mm)
Figure A
#1 Check Diagrams
Relief Valve Discharge Rates 21⁄2" – 10" (65 - 250mm)
lpm gpm
1330 350
1140 300
950 250
760 200
570 150
Rate of Flow
380 100
190 50
0 0
0 20 40 60 80 psi
0 138 276 413 551 kPa
957, 957RPDA and LF957RPDA
Pressure
Figure B
Figure C
Figure D
#2 Check Diagrams
Figure D
!
WARNING
Prior to servicing any Watts valve, it is mandatory to shut down
the water system by closing both the inlet and outlet shutoff
valves. After shutoff valves are closed, open test cock #2, #3
and #4 to relieve pressure within the backflow assembly.
1. After #3 test cock has been opened to relieve pressure,
remove #3 test cock from housing. (Figure A)
2. Insert a #3 screwdriver through the hole on the top of the
cover sleeve and using both hands rotate the cover sleeve
approximately
1
⁄4-turn clockwise and 1⁄4-turn counter-clockwise to break the sleeve O-ring seals. Using the screwdriver,
slowly slide the cover sleeve to the downstream side of the
housing. (Figure B)
3. Remove the stainless steel check retainer from the housing.
(Figure B)
4. Remove the #1 check module (Figure C) by inserting two flat
blade screwdrivers into the slots on either side of the check
module and gently pry the check module toward the open
zone.
2
Figure E
Figure E
Figure F
Figure F
5. Remove #2 check module with the same instructions as in #4
above. For servicing 6" (150mm) checks see 8" – 10" (200 –
250mm) instructions on p. 4.
6. To clean or inspect either check module, insert a #3 screwdriver through the downstream side of the check module as
shown in Figure D and E. When the screwdriver is in place,
remove the E-clip (Figure F) and pin connecting the structural
members and the check clapper will open with no tension.
7. Thoroughly clean the seating area. The sealing disc may be
removed, if necessary, by removing the screws connecting the keeper plate to the clapper. The sealing disc may be
reversed and reinstalled if the elastomer is cut or damaged.
8. Wash check module and O-ring and inspect for any damage.
If damaged, reinstall new parts.
9. After thorough cleaning, lubricate O-ring w/FDA approved lubricant, replace pin and E-clip in structural members, remove
screw driver and reinstall check modules and assemble housing in reverse order of these instructions.
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