Spring Verification - Fisher 667 Instruction Manual

667 Size 30-76 and 87 Actuators
June 2011
When determining valve friction, you can make diaphragm pressure readings at a travel position other than mid-travel
if you desire. If you take readings at zero or at the full travel position, take extra care to ensure that the readings are
taken when the travel just begins or just stops at the position selected.
It is difficult to rotate the spring adjustor (key 74, figure 6, 7, and 8) when the full actuator loading pressure is applied
to the actuator. Release the actuator loading pressure before adjusting. Then re-apply loading pressure to check the
adjustment.

Spring Verification

Ensure that the actuator diaphragm is at the bottom of its travel as shown in figure 4 and not connected to the valve.
(Note: Some spring compression is required to move the diaphragm to the bottom of its travel.)
Also, provide a certified pressure gauge that will accurately read the diaphragm pressure from 0 through the upper
bench set pressure marked on the nameplate. Apply loading pressure to the diaphragm.
Stroke the actuator a few times to ensure that the pressure gauge is working correctly, and that the actuator is
functioning properly.
CAUTION
To prevent product damage, it is important to ensure that the actuator assembly is not binding or producing any friction on
the actuator stem movement.
Key numbers are shown in figures 6, 7, and 8.
For Direct-Acting Valves (PDTC [Push Down to Close])
1. If not already accomplished, push the valve stem down away from the actuator to the closed position.
2. Set the diaphragm loading pressure to 0.3 bar (5 psig) over the upper bench set pressure. The upper travel stop
should be contacting the diaphragm casing.
3. Slowly decrease the pressure towards the upper bench set pressure while checking for the first movement of the
actuator stem.
Note
Before turning the spring adjuster on size 70, 76, or 87 actuators, assemble the stem connector around the actuator stem and the
anti-rotating lug on the yoke. Mark the actuator stem as a visual reference to verify that stem rotation does not occur. Remove the
stem connector before rechecking the bench set.
4. If movement occurs before or after the upper pressure is reached, adjust the spring adjuster (see figure 4). Thread
the adjuster up or down on the actuator stem until the actuator stem movement is first detected at the upper
bench set pressure. (Note: You may need to lower the loading pressure to reduce spring compression, allowing the
spring adjuster to turn.)
5. Be sure the spring adjuster is adjusted to meet the requirements of step 4 above.
6. Apply the lower bench set loading pressure to the diaphragm. This will extend the actuator stem toward the valve.
Mark the end of the actuator stem on a nearby surface using tape or some other method.
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Instruction Manual
D100310X012