INSTRUCTIONS FOR INSTALLING
Series 800
Anti-Siphon Pressure Type
Vacuum Breaker
Sizes:
1
⁄
2
" through 2" (15-50mm)
When installed in accordance with these instructions
this valve is designed to prevent back-siphonage of
polluted water into a potable water supply. The No.
800 is ideally suited for industrial processing systems
and other continuous pressure applications. The valve
can be placed in the hot or cold supply lines connected
to a potable water supply system where water enters
the equipment below its overflow level.
Examples:
Where there is no danger of freezing and a drain or run-
off is available.
Cooling Tower and Process Water
Commercial Laundry Machines
Swimming Pools
Chemical Plating Tanks
Photo Tanks
Large Toilet and Urinal Facilities
Heat Exchangers
Degreasers
Live Stock Water Systems
PRESSURE - TEMPERATURE
Working Temp:
33
°
F - 210
°
F (56
°
C - 99
°
C)
Max. Pressure:
150 psi (10 bars)
Min. Pressure:
15 psi (1 bar)
Important Note: Vacuum breakers are not designed,
tested or approved to protect against backpressure
backflow or water hammer shock. For protection
against backpressure backflow, install a Watts Model
909 Reduced Pressure Backflow Preventer. For pro-
tection against water hammer shock install Watts Model
15 Shock Arrestors.
Im
po
rtant Start-Up
ASSE standard 1020 requires that the atmo-
spheric vent valve remains open until the valve
body pressure exceeds 1 psi. Until this pres-
sure is reached, some amount of spillage will
occure at the atmospheric vent. In order to
minimize this leakage on start-up, close the
downstream shut-off valve and open inlet
shut-off valve quickly.
Operation
When the down stream pressure drops to 1 psi or below,
the spring loaded disc float opens the atmospheric vent
and the spring loaded check valve closes the inlet. This
prevents the creation of a vacuum in the discharge line
and prevents back siphonage. As water flows through the
valve, it pushes the check valve open and lifts the disc
float which closes the atmospheric vent, thus preventing
leakage. The disc float is free floating without close fitting
guides which assures freedom from sticking. The durable
silicone disc on the disc float and check valve permits use
on hot and cold water lines.
3
⁄
4
" - 2" IAPMO Listed
Watts
No. 800
Watts No. 909
Reduced Pressure
Backflow Preventer
Meter
Potable Line
Non Potable Line
Wash
Sink
Drinking Domestic
Fountain Water Heater
Potable Supply - Flow
Tank
Vat
Degreaser
*12" Minimum (305mm)
IS-800
Isolation Potable Water System From Non-Potable Line
