26 September 2006
Backflow Prevention and Cross Connection Control
The installation of backflow prevention and cross connection control must comply
with the AWWA Manual M14, Recommended Practice for Backflow Prevention
and Cross Connection Control.
Fire Suppression Systems.
When backflow preventers are provided on a fire suppression system, NFPA 13
requires backflow preventers that are approved or listed for fire protection use by
acceptable testing agencies such as Underwriters Laboratories or Factory
Mutual. Because pressure loss through a valve can degrade the effectiveness of
a fire suppression system, design and submittal acceptance must ensure the
rated working flow rate of the valve selected or installed meets the flow
requirements of the system. Perform backflow prevention retrofit work when
systems are down for major renovation unless the threat dictates otherwise.
For systems connected to a potable water supply:
For new fire suppression system using water only as a fire suppressant, follow
base requirements for backflow prevention.
Install a reduced pressure type backflow device where antifreeze or other
chemicals are added into the system.
Retrofit on Fire Suppression Systems.
When backflow preventers are installed in an existing sprinkler system, a
thorough hydraulic analysis, including hydraulic calculations and flow test, must
be performed on the sprinkler system to ensure that the water supply is still
adequate for the system with the backflow preventer. If the backflow preventer
causes the demand to exceed the water supply, the backflow preventer must not
be installed until the water supply is corrected to support the new demand.
When backflow preventers are installed in fixed fire protection systems, test
connection must be provided downstream of all backflow prevention valves for
flow tests at system demand.
Where meters are installed on fire sprinkler and hose stream water distribution
systems, they must be listed by an NRTL as fire flow meters.