Fisher 9500 instruction manual Three-Way Valve Tandem Linkage

9500 Valve

Instruction Manual

Form 2433

November 2007

leakage downstream (between the bushings and disc hubs) may also indicate a need for hub seal adjustment.

To adjust the hub seals:

1.Tighten both thrust-plate cap screws (key 10) 1/4 turn on one side (the side where shaft leakage is occurring).

To check the linkage adjustment on Fishtail discs, the flat is on the same side of the shaft as the nose or leading edge of the valve disc (as shown in figure 2). When the valve disc is at the fully closed position, the flat will be either top-dead-center or bottom-dead-center in relation to the valve body. The top-dead-center position is shown in figure 2. A more accurate check of the fully closed disc position is obtained by removing the valve from the pipeline.

CAUTION

To avoid excessive side thrust on the disc and possible liner damage, tighten cap screws on both sides of the valve alternately and in 1/4-turn increments. Do not over-tighten by continuous turning or by tightening one side only. Over- tightening the cap screws will cause the liner to fail.

2.Tighten both thrust-plate cap screws 1/4 turn on the other side of the valve.

3.Repeat steps 1 and 2 until leakage stops.

Note

If this adjustment is being performed to stop minor leakage past the disc, check the leakage after turning the cap screws enough to move the thrust plates 0.8 mm (1/32 inch) closer to the valve body. If leakage has not stopped or diminished, the leakage is probably due to incorrect linkage adjustment or damaged valve parts. Refer to the Linkage section to check linkage adjustment; refer to the Maintenance section to inspect and replace parts.

4.If leakage around the shaft cannot be stopped by adjusting hub seals, refer to the Maintenance section to inspect and replace damaged parts.

Linkage

If the linkage between the power actuator and valve is improperly adjusted, the actuator may reach the end of travel before (or after) the disc reaches the fully closed position. This could result in leakage past the disc. The linkage adjustment is set at the factory, and it should not be necessary to adjust linkage unless the actuator and valve have been separated and the adjustment altered.

WARNING

To avoid personal injury and damage to the process system caused by the sudden release of pressure, isolate the control valve from all pressure and relieve pressure from the valve body before removing the valve from the line. Be sure the disc is closed so that it will not hit the mating flanges when being removed from the line.

With the valve removed from the line, position the actuator to the valve-closed end of the travel. Measure the distance between the valve face and the top and bottom edges of the disc as shown in figure 2. The disc is at the fully closed position if the two measurements are equal.

To adjust linkage, refer to the actuator instruction manual.

Three-Way Valve Tandem Linkage

If the valve is used as part of a three-way valve assembly, adjustment of the tandem linkage (see figure 5) may be necessary to ensure proper rotation of the slave valve disc.

If the adjustment is being performed with the three-way valve assembly out of the line, temporarily bolt the valve bodies to the tee to compress the liner faces until there is metal-to-metal contact between the valve bodies and the tee.

Check the rotation of the power valve disc per instructions in the Linkage section. If necessary, adjust the linkage between the actuator and the power valve.

To check the fully closed position of the slave valve disc, use the partial keyway on the slave valve shaft or measure equal distances between the slave valve face and the top and bottom of the slave valve disc as described in the Linkage section. Tighten the

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