Start Up; Installation - Watts LF909 Installation, Maintenance & Repair

Installation

A. Series 909/LF909 should be installed in a horizontal and upright
position. This positions the relief valve below the first check
valve, enabling the zone to drain through the relief valve outlet.
The shutoff valve with the test cock is to be mounted on the inlet
side of the backflow preventer. The test cock is on the inlet side
of the shutoff valve.
B. The 909/LF909 should always be installed in an accessible loca-
tion to facilitate testing and servicing. Check the state and local
codes to insure that the backflow preventer is installed in compli-
ance, such as the proper height above the ground.
C. Water discharge from the relief valve should be vented in accor-
dance with code requirements. The relief valve should never be
solidly piped into a drainage ditch, sewer or sump. The dis-
charge should be funneled through a Watts air gap fitting piped
to a floor drain.
D. Watts recommends a strainer be installed ahead of Watts 909
Series assemblies to protect the discs from unnecessary fouling.
E. Backflow preventers should never be placed in pits unless abso-
lutely necessary and then only when and as approved by local
codes. Consult your local or state plumbing or health inspector.
Watts recommends installation indoors or above ground in an
insulated enclosure.

Start Up

F. The downstream shutoff should be closed. Open upstream
slowly, fill the valve and bleed the air through Test cock 2, 3 and
4. When valve is filled, open the downstream shutoff slowly and
fill the water supply system. This is necessary to avoid water
hammer or shock damage.
G. The installation of a Watts air gap with the drain line terminating
above a floor drain will handle any normal discharge or nuisance
spitting through the relief valve. However, floor drain size may
need to be designed to prevent water damage caused by a cat-
astrophic failure condition. Do not reduce the size of the drain
line from the air gap fitting.
H. Two or more smaller size valves can be piped in parallel (when
approved) to serve a larger supply pipe main. This type of instal-
lation is employed where increased capacity is needed beyond
that provided by a single valve and permits testing or servicing of
an individual valve without shutting down the complete line.
The number of assemblies used in parallel should be determined by
the engineer's judgement based on the operating conditions of a
specific installation.
Indoors
Main
Meter Strainer
Above Ground
Now available, WattsBox Insulated Enclosures, for more information, send for ES-WB.
Parallel
Watts 909/LF909
2 ⁄ " – 10" (65 – 250mm)
1
2
Strainer
TaBlE OnE - capaciTy REQuiREd FOR sysTEM
50 GpM 100 GpM 150 GpM
Two 3 ⁄ " Two 1" Two 1
4
Devices Devices Devices
450 GpM 640 GpM 1000 GpM
Two 2 ⁄ " Two 3" Two 4"
1
2
Devices Devices Devices
Table shows total capacity provided with dual valve installations of various sizes.
Watts 909S/LF909S FDA
2 1 ⁄ " - 10" (65 - 250mm)
2
Air
Gap
12" (300mm)
Min. 12" (300mm)
Air Gap
200 GpM 250 GpM
1 ⁄ " Two 1 1 ⁄ " Two 1 1 ⁄ "
4 2 2
Devices Devices
2000 GpM 3000 GpM 5000 GpM
Two 6" Two 8"
Devices Devices
350 GpM
Two 2"
Devices
Two 10"
Devices
3