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42 | Baker Hughes
Air to Close / Reverse Acting Positioner
See Figure 18
.
1. Do not connect air supply or signal to the positioner. Valve is now open.
2.
Note the valve position. The travel indicator should be approximately aligned with the
open end of the travel scale. If not aligned, consult proper valve instructions for travel
adjustment.
3. Place lever S/A (3) to proper side (left or right) as designated by the appropriate cam
selection table for valve in question.
4. Run an independent regulated air line to the valve actuator in place of positioner output
line. Slowly apply proper air pressure through the regulator to shut the valve. Do not
exceed designated supply pressure. (Handwheel may be used to close the valve in place
of regulated air line.)
5. With valve closed, place cam holder (36) with truarc ring (37) into cam coupling (34).
6.
Place the cam (26) into the cam holder (36) so that the selected cam lobe is facing forward
and will rest on the cam follower. Secure cam to cam holder with washer (27), lockwasher
(51) and screw (28). Tighten screw (28) while holding the cam (26).
7.
With the valve closed, place the desired cam lobe’s low signal line on the cam follower.
With the low signal line resting on the cam follower sight across the face of the cam to the
raised reference line on the positioner case and align. (Low signal line and reference line.)
Center cam between the two arms of the lever S/A (3), then tighten set screws (35) to 87
inch-lbs. torque. (See Figure 18 on page 56 for cam mounting.)
8. Slowly reduce pressure applied to actuator in Step 4 to zero. (If handwheel was used to
place valve in closed position, back it off completely.) Valve is now open. Cam is at high
signal line on lobe.
9.
Disconnect the independent regulated air line to actuator and connect positioner output
line. Connect supply pressure and signal to positioner.
10. Adjust signal to low end of signal (i.e., 3 psig for a 3-15 psig range 4700P/4800P). Adjust
zero and span. Refer to
“Zero Adjustment”
and
“Span Adjustment” on page 37.
Summary of Contents for Masoneilan 4700P
Page 16: ...2021 Baker Hughes Company All rights reserved 16 Baker Hughes Figure 5 87 88 Actuator...
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Page 32: ...2021 Baker Hughes Company All rights reserved 32 Baker Hughes Figure 14 ATEX Installation...
Page 64: ...2021 Baker Hughes Company All rights reserved 64 Baker Hughes NOTES...
