Temperature Displays, DAS, I/O Modules, Transmitters and Calibration
Most temperature sensors used in monitoring and control do not have built in temperature displays, with the exception of non-electrical devices like glass thermometers, bimetals, phase change and filled systems.
Whether in manufacturing or R&D, wherever there is an electrical output temperature sensor or some sort of control action will be taken based on temperature values, there is a need for add-on devices to interpret the output signals.
The simplest of these for those sensors having an analog electrical output (thermocouples, thermistors, RTDs and radiation thermometers) is the meter.
Meters come in a variety of styles, shapes and sizes, but the major division of types is between analog and digital.
Analog meters are familiar enough, especially to anyone recalling the dashboard on a car with a meter that has a pointer that physically points to “H” or 200° or some other mark painted on the meter scale.
Digital meters are simply displays of numerical temperature values in familiar digits that change as the temperature reported by the sensor varies.
Still other temperature sensors find use connected to data acquisition systems or computer controllers. They need their signal carried, sometimes over extended distances, from the measuring point to the computer or system performing the actual control.
On and on it goes. There are many variations on the same theme.
The net result is a large variety of temperature sensor add-ons particularly in the monitoring and control of large power plants, process and various manufacturing plants.
Then, too, the task of performing a sensor or subsystem calibration or calibration requires trained staff with the proper equipment & facilities to maintain the traceable calibration of sensors.
Often, especially for smaller organizations, there may be one or two people with adequate equipment, facilities and training to perform such tasks. Small organizations, and, more and more today, larger ones are outsourcing their routine calibration or verification work to specialist suppliers.
Even more often, we see vendor calibration technicians coming to a plant to preform needed calibration work on-site.