2
Table 1.
Drain Size for Typical Flow Rates per Valve Size
VALVE SIZE
TYPICAL FLOW RATE
DRAIN SIZE
2
1
⁄
2
"
55 gpm
2"
3"
112 gpm
3"
4"
170 gpm
4"
6", 8", 10"
350 gpm
5"
Figure 2.
Series 909/LF909-FS Relief Valve Discharge Rates
ZONE PRESSURE (PSIG)
FLOW RATE (GPM)
2
1
⁄
2
" – 3"
4" – 10"
175
150
125
100
75
50
25
0
0 100 200 300 400 500 600 700 800 900
Relief Valve
First
Check
Second
Check
Second
Shutoff
Valve
Inlet
Shutoff
Valve
Figure 1.
Watts Series 909/LF909-FS
Sizes
2
1
⁄
2
" – 10"
Series 909/LF909-FS
Sizes: 2
1
⁄
2
" – 10"
• The relief valve module on 2
1
⁄
2
" – 10" Series 909/LF909-FS assemblies
may be turned to discharge to the opposite side. To do so, unbolt
the relief valve and turn the relief valve discharge port to the oppo-
site side. Mount the high pressure hose on the op po site side. This
should be done by a licensed journeyman, who is rec og nized by
the authority having jurisdiction, and only when space is critical for
testing or repair.
•
ASSEMBLY:
If the backflow preventer is disassembled during
installation, it MUST be reassembled in its proper order. The gate
valve with the test cock is to be mounted on the inlet side of the
backflow preventer. The test cock must be on the inlet side of the
wedge. Failure to reassemble correctly can result in water damage
due to excessive discharge from the relief port/vent and possible
malfunction of the backflow preventer.
NOTICE
The flange gasket bolts for the gate valves can loosen in storage
and shipment. Retighten the bolts during installation to align
the valves.
High Capacity Relief Series
• Backflow preventers must be installed in high-visibility locations to
allow for immediate notice of telltale discharge or other malfunction.
This location should also facilitate testing and ser vic ing, and protect
against freezing and vandalism.
• Installing a backflow preventer in a pit or vault is not rec om mend-
ed. However, if this becomes necessary, Watts highly rec om mends
that a licensed journeyman, who is recognized by the authority
having jurisdiction, be consulted. This type of installation and other
installation procedures must comply with all state and local codes
and meet the required safety provisions. An air gap below the relief
port must be maintained so as to avoid flooding and submersion of the
assembly, which may lead to a cross connection. Figure 1 shows the
primary components of the Series 909/LF909-FS.
• Pipelines should be thoroughly flushed to remove foreign material
before installing the unit. A strainer should be installed ahead of the
backflow preventer to prevent the disc from unnecessary fouling. Install
the valve in line with the arrow on the valve body, pointing in the direc-
tion of flow.
CAUTION
!
Do not install a strainer ahead of the backflow preventer on seldom-
used, emergency water lines such as fire sprinkler lines. The strainer
mesh could potentially become clogged with debris present in the
water and cause water blockage during an emer gen cy.
• 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 dis-
charge. See the relief valve discharge rates in Figure 2 and the typical
flow rates per valve and drain sizes in Table 1.
• When a Series 909/LF909-FS backflow preventer is installed for
dead-end service applications (such as boiler feed lines, cooling
tower makeup, or other equip ment with periodic flow requirements),
discharge from the relief vent may occur due to water supply pres-
sure fluctuation during static no-flow con di tions. A check valve may
be required ahead of the backflow preventer. Before installation,
see “Troubleshooting,” page 8.
Considerations for Installation
•
START UP:
At initial installation and after servicing, the down-
stream shutoff should be closed. Slowly open upstream shutoff
and allow the backflow preventer to fill slowly. Bleed air at each
test cock. When the backflow preventer is filled, slowly open the
down stream shutoff and fill the water supply system. This is
necessary to avoid dislodging O-rings or causing damage to
internal com po nents.
•
TEST:
The Series 909/LF909-FS backflow preventer may be test-
ed by a certified tester at the time of installation to ascertain that
the assembly is in full working order and may be relied upon to
protect the safe drinking water as per applicable standard.
Flood Sensor
