by Instrumentation in general
Instrumentation is a device or group of related devices used to:
measure
monitor
control a process
The purpose of process control instrumentation is
to measure, monitor, and control a process.
Process instruments fall into five different groups
primary elements and sensors
transmitters
controllers
transducers
final control elements
Transducers
is a device, usually electrical, electronic,
or electro-mechanical, that converts one type
of energy to another for various purposes including
measurement or information transfer
Sensors are electrical or electronic,
although other types exist. There are
Temperature sensors
thermometers, thermocouple
heat sensors
calorimeter is a device used to measure the heat of
chemical reactions or physical changes
Transmitter
is any device which converts measurements from
a sensor into a signal to be received, usually
sent via wires, by some display or control device
located a distance away.
Example
A pressure transmitter might use 4 ma as
a representation for 50 psig of pressure
and 20 ma as 1000 psig of pressure and any
value in between proportionately ranged between 50 and 1000 psig.
Technology transmitters used pneumatic pressure
typically ranged between 3 to 15 psig (20 to 100 kPa)
to represent a process variable
Process Controllers
Control and monitor a temperature, pressure,
level or flow process variable in batch and continuous processes
