Badger Meter Research Control Valve - Manual (Page 11)

13. CAUTION - With valves having “P” trims, be sure
the plug enters the seat before starting the bonnet
threads into the body.
14. Assemble the topworks to the body-bonnet assembly
in the exact reverse order from dismantiling. On air-to
open topworks remember to have air on the diaphragm,
rotating the topworks until the topworks and bellows
stem butts together in the middle of the connector. Use
two wrenches to tighten travel indicator lock nut to
preclude twisting the bellows. If the topworks is not in
the correct position with the stems butted together in
the middle of the connector, rotate the topworks
counterclockwise to the correct position before locking
down the stem locknut. Do not rotate more than 90°
15. See stroke adjustment and pressure test.
Valve Positioners
General
Badger’s valve positioners use the full force of the air
supply pressure to drive the diaphragm or piston of the
pneumatic actuator to a position corresponding to the
pneumatic instrument signal output from a controller
(pressure, temperature, flow, etc.) and hold that position,
regardless of the forces which tend to change valve
position.
Like all valve positioners, Badger’s have a feedback
circuit which measures position of the actuator’s
diaphragm or piston. The built-in valve positioner
supplies or vents air in response to the control-instrument
signal stroking the valve to the required position.
Integral Mounting
Badger’s compact valve positioners incorporate a single
axis force-balance principal of operation to insure
accurate and stable positioning of Research Control
Valves. The positioners become an integral part of the
valve actuator. In all cases, including bottom loading
applications, the built-in valve positioner is mounted
directly on the topworks with no external piping or other
exposed mechanisms.
Range Springs
The position of the diaphragm or piston in the valve
actuator is sensed by the amount of compressive force
exerted by the range spring on the valve actuator
diaphragm assembly. Standard strokes are 7/16" and
9/16". Standard signal ranges are 3-15, 3-9, 9-15, and
6-30 PSIG. Consult the factory for other ranges.
Top Loading, Air-to-Close
Air pressure from the control instrument is exerted
between the two lower diaphragms. Because of the
difference in the two diaphragm areas, the resultant force
is exerted in an upward direction. In balance condition,
the pneumatic force on the diaphragm plus
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