• Install backflow preventers in high-visibility locations to allow for
immediate notice of telltale discharge or other malfunction. This
location should also facilitate testing and servicing, and protect
against freezing and vandalism.
• Do not install a backflow preventer in a pit or vault. Ensure that
all local codes and required safety provisions are met. 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.
• Install a strainer ahead of the backflow preventer to protect all
internal components from unnecessary fouling.
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 emergency.
• Consider using an air gap and a fabricated indirect waste line to
accommodate normal discharge and nuisance spitting. Floor drains
of the same size must be provided in case of excessive discharge.
• Determine if a check valve is required ahead of the backflow preventer.
When a backflow preventer is installed for dead-end service
applications (such as boiler feed lines, cooling tower makeup, or
other equipment with periodic flow requirements), discharge from
the relief vent may occur due to water supply pressure fluctuation
during static no-flow conditions. *See “Troubleshooting,” before
installation.
• Observe the direction of the flow arrows on the valve assembly.
The backflow preventer is designed so that the critical level of the
relief valve is positioned below the first check. This unique feature
allows the valve to be installed either vertically or horizontally.
• Follow guidelines for the specific installation option selected, that
is, indoor, outside, or parallel. The installation procedure must
comply with all state and local codes.
• Before installation, thoroughly flush all pipelines to remove any
foreign matter.
• At the start-up of initial installation and after servicing, be sure the
downstream shutoff is closed. Slowly open the 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 components.
• Have the backflow preventer examined by a certified tester at the
time of installation to ascertain that the assembly is in full working
order and that it can be relied upon to protect the safe drinking
water as per applicable standards.
First
Check
Relief
Valve
Second
Check
LF909-QT-FS
2
Installation Guidelines
CAUTION
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