Accessory Repair - Pentair Anderson Greenwood 93 Series Installation And Maintenance Instructions Manual

Anderson Greenwood SerieS 93 PoSitive PreSSure PoSrv
InstallatIon and MaIntenance InstructIons

5 Accessory repAir

5.1 check valve
A check valve is used in the pressure sense
line to the pilot when the safety valve is
equipped with a field test or backflow preventer
accessory. A check valve is also installed
between the pilot dome connection and main
valve when the safety relief valve is equipped
with a backflow preventer.
the check valve used in the pressure sense line
is shown in Figure 6. this type of check valve is
also used for the backflow preventer accessory
between the pilot dome connection
and main valve for set pressures below
15 psig. the diaphragm is the only part that
should require servicing. if the diaphragm
is to be replaced, care should be taken not
to scratch or distort it in the center nozzle
sealing area. When reassembling the check
valve, uniformly tighten the body bolts, first one
side, then the opposite side until all are tight.
Do Not overtiGHteN bolts as this will distort
the diaphragm and cause leakage. For set
pressures below 1.0 psig, a diaphragm gasket,
item 9, may be used between the diaphragm
and lower body. if the check valve has one,
replace it with a new one.
if the check valve is not equipped with one,
do not put one in.
the check valve used for the backflow
preventer accessory between the pilot dome
connection and main valve for set pressures
15 psig and above is shown in Figure 6A.
the o-ring, item 4, is the only part that should
require servicing. remove item 1 to replace
o-ring.
inlet
FiGure 6
pArts list
item description
1 Hex head cap screw
2 upper body
3 Diaphragm
4 Nut
5 Lower body
6 Spring pin
7 Lockwasher
8 Diaphragm support washer
9 Diaphragm gasket
optional
accessory port
(normally
plugged)
FiGure 6A
pArts list
item description
1 Body
2 Spring
3 Ball
4 o-ring seat
5 tee
outlet
Flow
Pilot dome connection
to valve outlet
Flow
ref
8