Term
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Definition
a power operated device which modifies
the flow rate of a process control system in response to
control system signals. |
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Term
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Definition
a device that allows remote positioning of a
control valve in response to electrical, pneumatic, or
hydraulic control signals. |
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Term
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Definition
a structure by which the diaphragm case or cylinder
assembly is supported rigidly on the bonnet assembly |
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Term
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Definition
(Inherent Diaphragm Pressure Range)
The pressure required to operate a given actuator full stoke
without external forces or friction, such as packing frictions
or fluid forces (often referred to as “bench set” range) |
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Term
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Definition
The air pressure required to fully
retract the actuator stem. This represents the force
required to offset spring tension. |
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Term
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Definition
The additional force applied to a valve
plug once the plug has contacted the seat. |
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Term
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Definition
An assembly including the part
through which a valve plug stem moves an means for
sealing against leakage along the stem. It usually
provides a means for mounting the actuator. |
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Term
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Definition
The internal parts of the valve which are in flowing
contact with the controlled fluid. i.e.; (in a globe valve body,
trim would include valve plug, seat ring, cage, stem, stem
pin. |
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Term
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Definition
A hollow cylindrical trim element that is a guide to
align the movement of a valve plug with a seat ring and/or
retains the seat ring in the valve body. |
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Term
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Definition
a device which converts an input
signal (pneumatic, electronic) to an output control signal
which will position a control element (valve , damper) to the
required position. |
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Term
| Define: Positioner Deadband |
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Definition
The amount that the input
signal must change before the positioner responds with a
change in the output signal. |
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Term
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Definition
method of process control
where the position or condition of the final element is fed
back to another control device to aid in positioning or
controlling that device. |
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Term
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Definition
A signal or response which is fed back to
another control device to aid in positioning or controlling
that device. |
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Term
Define: Split Range
Give an example of split range control |
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Definition
Where one control signal is used to
operate two or more final control elements.
Example: A process requirement with a minimum flow of 5 GPM and a maximum flow of 100 GPM.
One small valve used for the low flow application (3 – 9 psig from the positioner) is mounted in parallel with a large valve.
One large valve used for the high flow application (9 – 15 psig from the same positioner). |
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Term
| Draw a graph of the different valve characteristics. |
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Definition
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Definition
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