I N S T A L L A T I O N , O P E R A T I O N , M A I N T E N A N C E
IOM-F-765
Operation and Maintenance Manual
Pressure Vacuum Breaker
Model 765
Read and understand this
manual prior to installing,
operating or servicing this
equipment.
Model 765
Table of Contents
Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Typical Installations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Service Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Pressure Vacuum Breaker – Model 765. . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Troubleshooting Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Installation
1. The Pressure Vacuum Breaker Assembly
must be installed where it is accessible
for periodic testing or repair.
2. The device must not be installed in a
pipe line until the line has been flushed
of foreign material. Failure to flush the
lines completely may cause the check
members to become fouled and require
disassembly and cleaning.
3. The device must be installed so that the Air Inlet operates in the verti-
cal position (see diagrams). Installation in any other manner will cause
the device to malfunction.
4. The device should be installed where some spillage is not objection-
able, as instantaneous siphon conditions and pressure surges will
cause “spitting.”
5. When threading the device in line, place wrench only on ball valve hex
ends. Keep pipe dope off interior surfaces of valve.
6. After installation, open inlet ball valve to pressurize device. Slowly open
outlet ball valve to fill down-stream line.
NOTE:
The downstream pressure must be maintained above 5psi to
keep the spring loaded air inlet poppet closed. If check valve fails to
hold 10psi minimum, it has become fouled and must be cleaned. Close
both ball valves and bleed pressure from device before disassembly.
Refer to Maintenance Manual for proper service methods.
NOTE:
All devices are factory tested for proper operation. Any damage
caused by pipe line debris or improper installation is not included in the
product warranty. In case of malfunction, or possible warranty claim,
DO NOT REMOVE DEVICE FROM LINE.
Contact your local FEBCO
Representative.
7.
THE DEVICE MUST BE PROTECTED FROM FREEZING.
Thermal
water expansion and/or water hammer downstream of the backflow
preventer can cause excessive pressure increases. Excessive pressure
situations should be eliminated to avoid possible damage to the system
and device. See recommended freeze protection procedures. (Freeze
Protection 765—Technical Sheet FP765)
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