3
Installation Guidelines
Series 909/LF909-FS can be installed in various way in various
settings, as shown in Figure 3. Observance of these installation
guidelines is important for each configuration.
• Series 909/LF909-FS should be installed in a horizontal position
with the relief valve port aimed downward. 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
should be mounted on the inlet side of the backflow preventer. The
test cock is on the inlet side of the shutoff valve.
• Series 909/LF909-FS should always be installed in an accessible
location to facilitate testing and servicing. Check the state and
local codes to ensure that the backflow preventer is installed in
compliance, such as the proper height above the ground.
•
Water discharge from the relief valve should be vented in
accordance with code requirements. The relief valve should
never be solidly piped into a drainage ditch, sewer, or sump.
The discharge should be funneled through a Watts air gap
fitting piped to a floor drain.
• Watts recommends installation indoors or above ground in an
insulated enclosure.
NOTICE
Consult local authorities regarding acceptance of vertical installations.
• At startup, the downstream shutoff should be closed. Open
upstream slowly, fill the valve, and bleed the air through Test cock
No. 2, No. 3, and No. 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.
• The installation of a Watts air gap with the drain line terminating
above a floor drain handles any normal discharge or nuisance spit-
ting through the relief valve. However, floor drain size may need to
be designed to prevent water damage caused by a catastrophic
failure condition. Do not reduce the size of the drain line from the
air gap fitting.
• Two or more smaller size valves can be piped in parallel (when
approved) to serve a larger supply pipe main. This type of installa-
tion 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 judgment based on the operating conditions of a
specific installation.
Indoors
Above Ground
Parallel
WattsBox Insulated Enclosures; for more information, send for ES-WB.
Min. 12"
Strainer
Air Gap
Meter
Strainer
Main
Air
Gap
12"
support
Table 2.
Total Capacity with Dual-valve Installations of Various Sizes
50 GPM
100 GPM
150 GPM
200 GPM
250 GPM
350 GPM
450 GPM
640 GPM
1000 GPM
2000 GPM
3000 GPM
5000 GPM
Two
3
⁄
4
"
Two 1"
Two 1
1
⁄
4
"
Two 1
1
⁄
2
"
Two 1
1
⁄
2
"
Two 2"
Two 2
1
⁄
2
"
Two 3"
Two 4"
Two 6"
Two 8"
Two 10"
devices
devices
devices
devices
devices
devices
devices
devices
devices
devices
devices
devices
Figure 3.
Series 909/LF909-FS in Different Installations,
Sizes 2½" - 10"