Valve Stem Position Transmitter Cam Information; Valve Positioner Bypass Operation - Emerson Fisher 3582i Instruction Manual

3582, 582i, and 3583
January 2013
When cam A is the operating cam, there is a linear relationship between an incremental instrument pressure change
and the resultant valve stem travel. The flow characteristic is that of the control valve. Installing either cam B or C as
the operating cam changes the relationship between the incremental instrument pressure change and valve stem
travel, thereby modifying the valve flow characteristic.

Valve Stem Position Transmitter Cam Information

Note
If the small arrow on the valve stem position transmitter cam points up toward the nozzle, output pressure increases with
downward stem movement. If the arrow points down, output pressure decreases with downward stem movement. If the arrow is
pointing in the wrong direction, remove, reverse, and re‐install the cam. Refer to the Changing Cam Position section of this
manual.
Refer to figure 21 for key number locations. Unhook the spring (key 38), and remove the cam bolt and locking nut
(keys 6 and 45). Remove the cam (key 4) and spring retainer bracket (key 43). To install the cam, screw the locking nut
all the way onto the cam bolt. Attach the cam and spring retainer bracket with the cam bolt. Tighten the bolt to secure
the cam.
Then, tighten the locking nut against the spring retainer bracket. Hook the spring into the spring retainer bracket.
The linear cam is the only cam available for the 3583 valve stem position transmitter. There is always a linear
relationship between stem travel and the stem position transmitter output.

Valve Positioner Bypass Operation

3582 and 3582D valve positioners, and 3582NS positioners with bypass, are supplied with a bypass assembly. A handle
on the bypass assembly permits selecting positioner or bypass operation. Refer to figure 24 for key number locations.
CAUTION
Do not use bypass when the valve positioner is reverse‐acting or is in split‐range operation. In these cases, bypassing the
valve positioner sends the input signal directly to the actuator. Such a change will affect the desired operation and possibly
upset the system. Use bypass only when the input signal range is the same as the valve positioner output range required for
normal actuator operation.
Labels on the bypass block (key 34A) and a pointer on the bypass handle (key 34D) indicate if the input signal from the
instrument goes to the positioner or directly to the control valve actuator. Push the bypass handle toward the back of
the positioner to move the pointer over the word POSITIONER. With the bypass handle in this position, the input signal
goes to the valve positioner bellows and the output pressure of the valve positioner goes to the actuator. Pull the
bypass handle forward to move the pointer over the word BYPASS. In this position, the input signal goes directly to the
actuator.
Note
A difference between the input signal pressure and the valve positioner output pressure could cause a transient bump in the
controlled system when the bypass handle is moved to BYPASS.
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Instruction Manual
D200138X012