Pilot Valve Stroke Adjustment - ABB AV3 Instruction Manual

PILOT VALVE STROKE ADJUSTMENT

Tools required
REPAIR/REPLACEMENT PROCEDURES
7. Inspect the diaphragm assembly for distortion. If distortion occurs
repeat this procedure from the start.
8. Replace diaphragm cover (item 25) and screws (item 45). Make
certain diaphragm cover is properly seated. Torque cover screws to
0.9 Nm (8 in-lbs).
9. Transfer the positioner back to automatic operation (refer to
Section 5).
10. Apply input signal pressure and check for leaks around the dia-
phragm assembly using soapsuds solution.
11. Perform the procedure outlined in
ADJUSTMENT.
The purpose of this adjustment is to keep the valve stem in the proper
operating range. This procedure should be used in conjunction with
the following procedures:
GAIN HINGE SPRING
PILOT VALVE BODY
DIAPHRAGM ASSEMBLY
NOTE: For internal speed adjustment refer to
ADJUSTMENTS in Section 4.
When the valve stem is in the balance position, as shown in Figure
8-6, 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.
Two Allen wrenches (a normal size
wrench being at least 5 inches in length)
1. With the positioner cam at approximately 50%, manually lock the
actuator in position by:
a. Using manual override if available.
- or -
b. If manual override is not available, disconnect (and secure)
the linkage and plug ports 01 and 02.
2. Apply supply pressure.
3. Apply the maximum input signal to the positioner (20 mA for Type
AV3 positioner or a voltage pulse to the raise terminal for Type AV4
positioner).
PILOT VALVE STROKE
GAIN AND SPEED
⁄
-inch and a long
3
32
PILOT VALVE STROKE ADJUSTMENT
⁄
-inch
3
32
8 - 9