Bulletin 22-00 A / Page 5
and fully opening the valve. Th
is
pressure does not feed back through
the pilot plug, because the pilot plug
piston is fully seated.
Simply de-energize the ‘B’ feature on
the valve to regulate.
A4WS Principle of Operation
Th
e port plate for the A4WS is the
same port plate used for the A4WB.
Th
e only diff erence is the seal cap
and coil assembly is located in the
opposite location, as shown in the
A4WS principle of operation cross-
section. Th
e regulating portion of the
valve works in the same manner as the
A4W principle of operation.
Th
e ‘S’ feature, electric shut off , when
energized will cause the solenoid plug
to lift and allow the valve to regulate.
Th
e pressure on top of the piston is
released through passage (P), the pilot
plug, and into passage (T), lowering
the pressure. Th
e inlet pressure
acting on the bottom side of the
piston overcomes the outlet pressure,
therefore forcing the piston upward
and fully opening the valve.
When the ‘S’ feature is de-energized
passage (P) is blocked off and the inlet
pressure bleeds through the bleed hole
in the piston allowing for continuous
equalization of inlet pressure to the
top of the piston. Th
e top and bottom
pressure on the piston equalizes and
the weight of the piston along with the
closing spring force prevents the valve
from regulating.
Simply energize the ‘S’ feature on the
valve to regulate.
A4WBS Principle of Operation
Th
e port plate for the A4WBS is the
same port plate used for the A4WB
and A4WS. Th
e regulating portion of
the valve works in the same manner
as the A4WS described above. Th
e
A4WBS principle of operation cross-
section shows the ‘B’ and ‘S’ solenoid
features. When both solenoids are
de-energized, there is no fl ow from
the top of the piston and therefore
the pressure on top of the piston is
equalized to that on the bottom, inlet
pressure, through the bleed hole and
the valve is closed due to the weight
of the piston in combination with the
closing spring. When the ‘S’ solenoid
is energized it allows the valve to
regulate. When the ‘B’ solenoid is
energized it overrides the ‘S’ feature
and the valve will be fully open.
Note:
for more details on the
principles of operation for the ‘B’ and
‘S’ features see the previous single
operations.
A4WK and A4WBK Principle of
Operation
Th
e A4WK and A4WBk operate in the
same manner as the A4W and A4WB.
Th
ese regulators are factory set for
a given set pressure. Th
e seal cap is
wired to the bonnet cap screw and the
wires are sealed with a lead seal. Th
e
relief pressure setting is stamped on
the seal.
A4W Manual Opening Stem Cross Section
T
M
Manual
Bypass
Stem
T
M
Manual
Bypass
Stem
Manual Opening
Stem in Closed
Position:
Manual Opening
Stem in Open
Position:
Passage
Description
T
Outlet Pressure
M
Manual Opening Stem
Note:
If the lead seal is removed from
the ‘K’ featured valves prior to one
year of installation the warranty is
voided.
A4WE Principle of Operation
Th
e A4WE version of the inlet
regulator has a remote sensing
connection, which allows control of
upstream pressure at a point remote
from the regulator inlet. Th
e port plate
gasket (#35) has no hole, thus blocking
fl ow of upstream pressure to the under
side of the diaphragm. Th
e sensing
pressure from the desired control
point, upstream of the regulator, is
connected to the gauge port (#26).
Th
us the regulator will control the
pressure at the sensing point. Th
e
regulator operation and adjustment is
the same as the A4W.
