Xylem MM 110C Series PFC 1G PFC 1GR Modulating Pneumatic Liquid Level Controls - Manual (Page 2)

2
The model PFC should be installed vertically on the side
of the tank or vessel and connected with 1” equalizing
pipes. Plug all unused body connections. Control must be
plumb, with no more than a 2°-3° slant in any direction.
Control should be set with mark on casting 1” below the
desired operating level in tank. Keep equalizing lines as
short as possible and avoid creating any pockets. Crosses
with plugs should be used at any right angle connections
to facilitate cleaning. A blow-off valve should be installed
to permit blowdown operation and draining the float
chamber. All connections must be securely tightened in
leak-tight arrangement.
Gauges should be positioned for convenient reading.
Head assembly can be reoriented by removing 8 bolts in
the top of the head assembly and repositioning the entire
head as desired so gauges can be read conveniently.
Piping Hook-up
INSTALLATION – Boiler / Hydronic Installation
TOOLS NEEDED:
Two (2) pipe wrenches, one (1) flathead screw driver
and pipe thread dope.
FACTORY SETTINGS
DIRECT ACTING—MODEL PFC-1-G - The higher the liquid
level, the higher the output pressure. Control can be changed
to Reverse Acting.
REVERSE ACTING—MODEL PFC-1-GR - The higher the liquid
level, the lower the output pressure. Control can also be changed
to Direct Acting.
NOTE: Pneumatic operated valves are also available as either
Direct Acting or Reverse Acting. When control and valve are the
same –both Direct Acting or Reverse Acting– the valve opens
as liquid level falls. When they are not the same, valve opens
as level rises.
MAXIMUM PROPORTIONAL BAND—Control goes through
its full operating range—from 3 to 15 psi output— with 2” of
level change inside the float chamber. The proportional band
can be adjusted to as little as 1” of level change.
SET POINT—The mark cast on float housing indicates the
low point of the control operating range. The operating level to
be maintained in the tank should be 1” above this mark. This
set point can be field adjusted about 3/4”.
OPERATION
The model PFC is float operated, and
mounts on the side of the tank or pressure
vessel. Its design allows field adjustment of
operational level, adjustment of proportional
band and conversion to either direct acting
or reverse acting operation.
Remove float blocking plug and dowel pin, located
in the bottom tapping of the control, before installa-
tion. Remove cardboard stop inside the top housing
before putting control in operation.
When using tape sealants on pipe or fittings external
threads follow the manufacturer's instructions—do
not place tape on first thread. When using thread
joint compound on pipe or fittings external threads
follow manufacturer's instructions—use sparingly
do not place compound on first thread.
! CAUTION
Operating
Range
Proportional
Band
Output Air
2" (51mm) 100%
1" (25mm) 50%
3 6 9 12 15
(.2) (.4) (.6) (.8) (1)
Reverse
Acting
Direct
Acting
psi
(kg/cm 2 )
NORMAL
OPERATING
LEVEL
BALL VALVE
GATE VALVE
DUAL
VALVES
FOR
BLOW
DOWN
OUTPUT AIR TO
CONTROL DEVICE
1”
SUPPLY AIR
NOTE
The control is factory set to the mark on the float housing and
to maximum proportional band. If the proportional band is
adjusted, the point of minimum output may be as much as 1/2”
above the mark.
Be sure to release pressure from float chamber
before removing the 8 bolts.
! CAUTION
IMPORTANT
Follow the boiler manufacturer’s instructions along with all
applicable codes and ordinances for piping, blow-down valve,
water gauge glass, tri-cock and electrical requirements.