3583 Valve Stem Position Transmitters - Emerson Fisher 3582i Instruction Manual

3582, 582i, and 3583
January 2013

3583 Valve Stem Position Transmitters

3583 (3583, 3583C) pneumatic valve stem position transmitters are mechanically linked to the valve stem in a
diaphragm‐actuated, sliding‐stem control valve package. A change in the position of the valve stem changes the
output pressure produced by the position transmitter. This signal is then piped to a reporting or recording device to
indicate valve stem position.
The action of a valve stem position transmitter can be changed by reversing the internal cam. The valve stem position
transmitter cam is supplied with an arrow stamped on one side. The cam can be positioned to obtain either increasing
or decreasing output pressure with downward stem motion. If the cam arrow points toward the nozzle, the output
pressure increases; if the cam points away, the output pressure decreases with downward stem motion.
Figure 19 depicts a diaphragm actuator which produces downward stem motion for increasing actuator pressure. For
a stem position transmitter, the flapper assembly is always positioned in the reverse‐acting quadrant of the beam.
Supply pressure is connected to the 83L relay. A fixed restriction in the relay limits flow to the nozzle so that when the
flapper is not restricting the nozzle, air can bleed out faster than it is being supplied.
Figure 19. Schematic Illustration of Fisher 3583 Transmitter
ROTARY
SHAFT
ARM
TRAVEL PIN
22A7964‐A
A2454‐4
As the pressure to the diaphragm actuator increases, the valve stem moves downward, causing the internal cam to
rotate. Cam rotation causes the beam to pivot about the input axis moving the flapper closer to the nozzle. The nozzle
pressure increases which, through relay action, increases the output pressure.
The output pressure is also connected to the bellows. As the output pressure increases, the bellows expands, causing
the beam to pivot about the feedback axis moving the flapper slightly away from the nozzle until equilibrium is
reached. The position transmitter output pressure is now proportional to the valve stem position.
As the pressure to the diaphragm actuator decreases, the valve stem moves upward, causing the internal cam to
rotate. Cam rotation causes the beam to pivot about the input axis moving the flapper away from the nozzle. The
nozzle pressure decreases which, through relay action, decreases the output pressure. The bellows contracts, causing
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OUTPUT TO STEM
POSITION INDICATOR
OR RECORDER
SUPPLY
PIVOT
RELAY
BELLOWS
INPUT AXIS
NOZZLE
FLAPPER
BEAM
FEEDBACK AXIS
CAM
OPERATIONAL
QUADRANT
Instruction Manual
D200138X012