Xylem MM 110C Series PFC 1G PFC 1GR Modulating Pneumatic Liquid Level Controls - Manual (Page 5)

When the control is placed in service, and after any adjustment,
make sure that magnets clear the tower tube. With cover
removed, move the yoke manually through a full arc of travel.
If necessary to adjust: Loosen pivot screw lock nut (B), using a
11/32” wrench. Adjust pivot screw (not shown) in a direction to
free the rubbing. When magnets clear tube properly, tighten
lock nut securely, and make sure the yoke is engaged with
internal armature.
After installation, test the control for operating levels and reposition
the mechanism, if necessary. Make sure the magnets are
engaged with the internal armature. Engagement is indicated
by resisting movement. Replace cover.
5
Remove two locking screws at bottom of proportional band
spring bracket (F). Remove proportional band adjusting screw
and coil spring (G). Remove proportional band spring bracket
and U-shaped proportional band spring (H). It may be necessary
to compress U-shaped spring slightly to withdraw it from the
upper spring follower (J) and lower guide (K).
Loosen two inner pivots (L), using a 5/16” open end wrench
on the hex-shaped base of the pivots. Rotate counterweight
(M) 180° until it rests on the stop. The eccentric will display DA
when in the proper position for direct acting, and RA for reverse
acting operation.Tighten the two inner pivots (L) securely against
the yoke.
Swing spring follower (J) back to upright position. Carefully
replace proportional band spring bracket and U-shaped propor-
tional band spring (H), making sure that top leg of spring passes
inside the spring follower and between the two upright arms,
and the bottom leg passes inside the guide (K).
Replace proportional band adjusting screw and coil spring (G).
Tighten adjusting screw until the lock screws (F) can be replaced
through the slots in the proportional band spring bracket.
Adjust proportional band as desired (see above) and tighten
lock screws (F).
To Change Direct Acting Operation to Reverse Acting Operation
START-UP AND ADJUSTMENT PROCEDURE (continued)
If Magnets Rub on Tower Tube
One of the pivots on the yoke arm is spring loaded; any lateral force
on the yoke may give a false picture of actual clearances.
! CAUTION
G
K
H
J
L
F
M
Overtightening could loosen the eccentric from the lead
counterweight.
! CAUTION
Perform the air output adjustment procedure after any other changes
to the mechanism.
! IMPORTANT
B