User Guide

ManualsBrandsFebco ManualsBackflow Preventers1"LF825Y-QT Quarter Turn Reduced Pressure Zone Assembly (Lead Free)

MAINTENANCE MANUAL MODELS 825Y, 825YA, 825, 825D, 825YD & 826YD

Feature and Operating Procedures

FEBCO manufactures several models of Reduced Pressure Backflow

preventers. The Model 825Y and 825YA are available in sizes 3/4–2"

with bronze body and cover as standard. Other materials are avail-

able. The FEBCO Model 825 sizes 21/2–10" were manufactured with

cast iron. The FEBCO Model 825 Type D and 825 Type YD sizes

21/2"–10" are manufactured with standard body material of ductile

iron.

The FEBCO Reduced Pressure Backflow preventer assembly con-

sists of two independently operating, spring loaded check valves

with a pressure differential relief valve located between the two

checks. The pressure drop across the first check valve is approxi-

mately 6.0 psid with no flow. The relief valve consists of a hydrauli-

cally balanced diaphragm with the high pressure side hydraulically

connected to the upstream side of the first check. The low pres-

sure side is hydraulically connected to the reduced pressure zone,

thus the relief valve remains closed during normal operation. The

low pressure side of the diaphragm is spring loaded to force the

relief valve open when the pressure drop across the first check (and

across the diaphragm) reduces to approximately 2.5 psid. A com-

plete assembly includes two shut-off valves and four test cocks.

Example sectional views below show typical components and flow

passages with corresponding pressure readings (no flow conditions)

at the various locations within the assembly.

Reduced Pressure Backflow Preventer

*Relief Valve

Rotated 90º for Clarity

Model 825Y (

/4–2")

Figure No. 1

Model 825YD (2

/2–10")

Figure No. 2

Inlet Shutoff

Outlet Shutoff

First Check

Second Check

100 PSI

93 PSI

Relief Valve*

Reduced

Pressure

Zone