Watts 909 Serie Manuel D'installation, D'entretien Et De Réparation page 3

Installation Guidelines
Series 909/LF909 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 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 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 installation
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.
Table 2. Total Capacity with Dual-valve Installations of Various Sizes
50 GPM 100 GPM 150 GPM
Two ⁄ " Two 1" Two 1
3
4
devices devices devices
200 GPM 250 GPM
⁄ " Two 1 ⁄ " Two 1 ⁄ "
1 1 1
4 2 2
devices devices
Figure 3. Series 909/LF909 in Different Installations,
Indoors
Main
Meter
Above Ground
WattsBox Insulated Enclosures; for more information, download ES-WB at watts.com.
Parallel
Strainer
350 GPM 450 GPM 640 GPM
Two 2" Two 2 ⁄ " Two 3"
1
2
devices devices devices
Air
Strainer
Min.
Gap
12"
Min. 12"
Air Gap
1000 GPM 2000 GPM 3000 GPM
Two 4" Two 6" Two 8"
devices devices devices
5000 GPM
Two 10"
devices
3