
PVB - Pressure Vacuum Breaker assemblies are used to protect against
health hazard and non health hazard backsiphonage conditions in
industrial plants, cooling towers, laboratories, laundries, swimming
pools and lawn sprinkler systems.

Febco 765 Pressure Vacuum Breaker assemblies should be installed at
least 12 inches above the highest piping outlet and downstream of the
assembly to preclude backpressure. In a sprinkler system that means the
Febco 765 Pressure Vacuum Breaker must be installed 12 inches above the
highest head in the irrigation system.
Febco 765 PVB assemblies should be
installed so they are easily accessible for maintenance, periodic
testing, and where discharge will not be objectionable. They should be
protected from freezing. If the assemblies are subject to freezing
temperatures, the freeze protection procedures outlines in the service
manual that is included with the Febco 765 Pressure Vacuum Breaker must
be followed. Assemblies must not be installed where backpressure could
occur.
The discharge pressure of the Febco 765
pressure vacuum breaker shall be maintained above 3.0 PSI on 1/2 in
though 1 1/4 in sizes and 5.0 PSI on 1 1/2in and 2 in sizes to insure
seating of the spring loaded air inlet poppet.
Thermal expansion of water and / or water
hammer down stream of the backflow presenter can cause pressure
increases. Excessive pressure should be eliminated to avoid possible
damage to the system and assembly.

Pressure Vacuum Breaker assemblies shall be installed to withstand
pressure for long periods and to prevent backflow of contaminated water
into the potable water system in backsiphonage conditions. The Pressure
Vacuum Breaker assembly shall consist of a single spring loaded check
valve which closes tightly when water flow through the assembly drops to
1 PSI.
The assembly shall include two resilient
seated shut-offs and two resilient seated test cocks, considered
integral to the assembly. Assemblies must be factory backflow tested.
The check valve and air inlet valve must be constructed to allow in-line
servicing of the assembly. The valve body shall be constructed of
bronze. The check, poppet and bonnet assembly shall be constructed of
engineered plastic to protect the valve body from damage in the event of
freezing.
Pressure Vacuum Breaker assemblies shall
be installed a minimum of 12 inches above the highest downstream outlet,
and the highest point in the downstream piping. The assembly shall be
rated to 150 PSI working pressure and water temperature from 32 degrees
F. to 140 degrees F. The assembly shall meet the specifications of the
USC* approval.
Pressure Vacuum Breaker shall be Febco
765 or prior approved equal.