IOM-POSR-2
2
10. See Figure 2 for installation ori en ta tion
for hor i zon tal or vertical piping. For best
per for mance Cashco rec om mends in stall ing
in a well drained horizontal pipe, prop er ly
trapped.
Position “H”: Horizontal Pipe. Re quires
user to in stall sensing line on down stream
pip ing.
Position “VD”: Vertical pipe with down wards
flow direction. Requires user to install
sensing line on down stream pip ing.
Position “VU”: Vertical pipe with up wards
flow di rec tion. Pilot valve and main valve
shipped as separate units. Re quires user
to install pilot valve at down stream pipe tap
with a pipe nipple (not provided), provide
and install tub ing (4 tube fittings and two 4
ft (1.2 m) lengths of 1/4" OD copper tubing
supplied) to load ing cham ber tap and to
P
1
body tap from pilot valve.
11. Recommended installation is with pilot valve
spring chamber vertical upwards. Orient such
that the spring chamber vent hole does not
collect rainwater or debris.
12. Regulators are not to be buried underground.
13. For insulated piping systems, rec om men da tion
is to not insulate regulator.
This increases the loading pres sure on the
main valve’s plug and opens valve. Partially
closing the pilot valve’s plug will reduce its flow
to less than the amount bleed ing downstream,
and allows the loading pres sure on the main
valve’s piston to decay, allowing partial closing
of the main valve’s plug. This continues until
steady-state is de vel oped.
4. The pilot valve’s diaphragm(s) senses the
down stream (P
2
) pressure and compares the
force generated to the force developed by the
pilot’s range spring.
5. If, during operation, the downstream (P
2
)
pres sure falls below the pilot valve’s setpoint,
the main valve’s piston senses the reduced
pres sure on its underside and instantly moves
down, increasing the flow through the main
valve. At the same time, the pilot valve senses
the reduced pressure and the pilot valve’s
SECTION III
7. In placing thread sealant on pipe ends prior to
en gage ment, assure that excess material is
removed and not allowed to enter the reg u la tor
upon start-up.
8. Flow Direction. Install so the flow direction
match es the flow arrow on the body.
9. The POSR-2 comes factory piped between the
pilot supply and pilot loading. Install an external
sensing line from the 1/4" NPT con nec tion
opposite the factory piped pilot load ing port
to a point downstream at gauge location; use
1/4" OD metal tubing for dis tanc es 4 ft (1.2 m)
or less, and 3/8" OD metal tubing (requires
1/4" x 3/8" tubing adapter) for distances
greater than 4 ft. (1.2 m). The sensing line
should always be sloped down ward so that
condensation will drain away from the pilot.
If regulator pipe line is ex pand ing to a larger
pipe line, always connect sens ing line to the
larger pipe line.
III. PRINCIPLE OF OPERATION
A. General:
1. The POSR-2 pilot obtains its operating me di um
from the main valve body inlet. Down stream
pressure (P
2
) registers on the un der side of
the main valve’s piston and the pilot valve’s
diaphragm(s).
2. The loading pressure on the top side of the
main valve’s piston is an intermediate pres sure
higher than the downstream (P
2
) pres sure by
the sum of the pressures required to overcome
the main valve’s plug unbalance force and the
piston spring’s force.
3. The pilot has a bleed orifice that continuously
bleeds part of the loading medium down stream.
In op er a tion, the pilot valve’s plug can flow
more medium than is bleeding down stream.
CAUTION
DO NOT HYDROSTATIC TEST THROUGH AN IN STALLED
UNIT, INCLUDING PILOT; ISOLATE BOTH PILOT AND MAIN
VALVE FROM TEST. The upper range spring pressure
level listed on the nameplate is the rec om mend ed “upper
operative limit” for the sens ing diaphragm(s) in the pilot.
Higher pres sures could cause internal damage. In addition,
note on the name plate that the Inlet and Outlet pressure
and tem per a ture ratings are at different levels.
