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Instruction Manual
D100310X012
Discussion of Bench Set
The bench set pressure values are used to adjust the initial compression of the actuator spring with the valve‐actuator
assembly "on the bench." The correct initial compression ensures that the valve‐actuator assembly will function
properly when it is put into service and the proper actuator diaphragm operating pressure is applied.
The bench set values are established with the assumption that there is no packing friction. When attempting to adjust
the spring in the field, it is very difficult to ensure that there is no friction being applied by "loose" packing.
Accurate adjustment to the bench set range can be made during the actuator mounting process by making the
adjustment before the actuator is connected to the valve (see the Spring Verification Procedure).
Figure 4. Bench Set Adjustment
SPRING
ADJUSTER
ACTUATOR STEM
UPPER BENCH
SET LOADING
PRESSURE
3
LOWER BENCH
SET PRESSURE
MARK
4
VALVE STEM
50A8379‐C
B2429‐1
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 0.3 bar (5
psig) above the upper operating range 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 actuator damage, it is important to ensure that the actuator stem is stroking smoothly and not exhibiting
binding or excessive friction between the actuator stem and the bushing (key 7). Binding or excessive friction could be an
indicator of incorrect assembly or damaged parts.
RATED VALVE
TRAVEL MEASURE
4
MARK VALVE
STEM HERE
2
667 Actuator (Size 30/30i - 76/76i and 87)
NOTES:
1
THE LOWER PSIG LOADING PRESSURE (MARKED
ON NAMEPLATE) WHERE THE FIRST MOVEMENT OF
ACTUATOR STEM IS DETECTED.
2
MARK THIS POINT WITH TAPE OR A MARKER.
3
THE UPPER PSIG LOADING PRESSURE RETRACTS
ACTUATOR STEM.
MEASURE DISTANCE OF TRAVEL. IT SHOULD EQUAL
4
THE TRAVEL SHOWN ON THE NAMEPLATE.
LOWER BENCH SET
1
LOADING PRESSURE
May 2018
7
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