ABB AV1, Operating Instructions Manual

Page: 67 / 126

REPAIR AND REPLACEMENT
PILOT VALVE STROKE ADJUSTMENT
8 - 7
6. Replace the washer (Item 54) and screw (Item 53). Torque the
screw to 0.35 Nm (50 in.-oz.) while securing the diaphragm support
(Item 23) so it does not rotate.
NOTE: Item 53 is replaced by SEM screw NBMHA13006A as of
November 23, 2009/Serial Number 3K620000029936 & Item 54
is no longer used.
7. Inspect the diaphragm assembly for distortion. If distortion occurs
loosen the screw (Item 53), straighten the diaphragm and tighten
while holding Item 23 still.
8. Replace the diaphragm cover (Item 25) and screws (Item 45).
Make certain the diaphragm cover is properly seated. Torque the
cover screws uniformly to 0.9 Nm (8 in.-lbs).
9. Transfer the positioner back to automatic operation ( Section 5 ).
10. Apply the input signal pressure and check for leaks around the
diaphragm assembly using soapsuds solution.
11. Perform the procedure outlined in PILOT VALVE STROKE
ADJUSTMENT .
PILOT VALVE STROKE ADJUSTMENT
The purpose of this adjustment is to keep the valve stem in the
proper operating range. This procedure should be used in con-
junction with the following procedures:
•
Gain Hinge Spring .
•
Pilot Valve Assembly .
•
Diaphragm Assembly .
NOTE: For internal speed adjustment refer to PILOT VALVE
STROKE ADJUSTMENT in Section 4 .
When the valve stem is in the balance position, as shown in Fig-
ure
8-3 , the stem is flush with both ends of the valve body. There
are two adjustment screws to adjust. Use the following procedure
to check and adjust the travel of the valve stem:
Tools required:
•
-inch Allen wrench (standard length).
•
-inch Allen wrench (long length — at least five inches).
1. With the positioner cam at approximately 50%, manually lock
the actuator in position by:
a. Using manual override if available.
- or -
3
32
⁄
3
32
⁄