Overview

To calibrate temperature sensors you need a source of heat and a calibration standard. The sensor being calibrated and the standard are compared as they are exposed to the same temperature conditions provided by the heat source. To calibrate temperature signal conditioning or displays you need a standard that simulates the sensor output. Alternatively, the sensor and conditioner or display can be calibrated as a system by comparing the system output to the temperature measured by a standard that is exposed to the same temperature as the system sensor.

The overall cost of performing temperature calibrations is usually higher than for other types of calibrations. This is because of the cost of calibration equipment, the cost of calibration facilities, and the amount of time spent on the calibration. The calibration time is dictated by the time it takes the heat source to reach a set temperature and stabilize at that temperature. This may take close to one hour when using precision temperature baths, and the only way to reduce time is to provide multiple baths that are set at different temperatures. In comparison, pressure changes using dead-weight testers can be accomplished in less than a minute. The facilities required to support temperature calibration include extraction fans or fume hoods, increased air conditioning capacity, and high levels of electrical power. These facilities and the size and weight of typical calibration baths means that the sensor will have to be removed from its location to a calibration laboratory for calibration. There...