Reduced Pressure Principle (RPP) Backflow Preventer Install -
Maintaing - repair Reduced Pressure Zone Assembly: Inline
(Underground) Installation Because the reduced pressure zone
assembly can be used on systems that distribute chemicals,
underground installation requirements are particularly
stringent. A drain to atmosphere is usually required and should
be provided. This means a PVC drain fitting sits at the bottom
of the valve enclosure and is connected to a drain line with
adequate fall (slope) to drain any accumulation of water away
from the valve enclosure to an area above ground with continuous
gravity flow (cannot be drained into a pit with a rim higher
than twelve inches below the reduced pressure zone assembly).
The drainage trench should be dug in accordance with the
irrigation site plan before the assembly is installed.
Typically, a reduced pressure zone assembly enclosure can be
either a job-built concrete vault or two twelve-inch deep valve
boxes stacked vertically with bottoms together. When u