Contact temperature instruments are instruments and Indicators designed for temperature monitoring and displaying. These instruments either require a sensor input or come equipped with an integral sensor. Non-Contact temperature sensing devices are typically infrared devices. Digital temperature sensing instruments are portable, have permanent probe(s) and a digital display. These thermometers are typically battery powered. A dial thermometer is a bimetal, gas-actuated, or vapor-tension-based thermometer. They display temperature and possibly min/max readings and/or other 'extras'. Laboratory thermometers are standard glass thermometers for laboratory settings and applications. Process controllers can be configured specifically for temperature and humidity processes. Temperature probes include probes for various temperature sensing applications. Common sensor types include thermostat or thermal switch, thermocouple, RTD element, thermistor, and thermal cutoff. The temperature measurement range is also important to consider.
Display style choices for temperature instruments include analog meters or indicators, digital readouts, and video display terminals. A Fahrenheit display is defined by 32 degrees at the ice point and 212 degrees at the boiling point of water at sea level. A Celsius display is defined by 0 degrees at the ice point and 100 degrees at the boiling point of water at sea level. Common outputs for temperature instruments include analog voltage, analog current, resistance, frequency or modulated frequency, switch output, serial interface, and parallel interface. Application software may be included for process monitoring and control. Options and features for temperature instruments include explosion proof, splash proof or waterproof, HVAC applications, and sanitary applications.