Thermometer: an essential device 

Depending on their field of activity, professionals choose different temperature sensor technologies. They can also select a multifunction measuring device that includes a number of parameters, including temperature, or, more simply, a thermo-hygrometer, which can measure both temperature and humidity accurately and reliably. Technicians also often use thermo-anemometers, which can measure airflow and temperature at the same time. 

These thermometers are widely used by all HVAC-R technicians in all their fields of activity, where temperature is a key parameter at the centre of their analyses: 

• Heating and combustion
• Ventilation and air conditioning
• Audit of clean rooms and regulated environments
• Control of air-conditioning systems in smart buildings and optimisation of indoor comfort
• Refrigeration and cold chain control 

Which portable thermometer technology should I choose?

The technology used in portable temperature measuring instruments is similar to the one used in transmitters. However, many models use infrared technology, which is well suited to mobile use. However, the main technologies are still thermocouple and RTD (preferably Pt100), which are highly responsive and reliable. Finally, some devices incorporate two temperature measurement channels, known as differential thermometers. 

Thermocouples use the electrical potential difference generated by two different metallic conductors to measure temperature. These sensors can reliably measure extremely low and high temperatures over very wide ranges, but they are sensitive to electromagnetic interference and their accuracy is not always optimal. There are many different types of thermocouples, each using different metals for the conductors, which affects the temperature range that the sensor can measure accurately. Thermocouples also have the advantage of being very responsive to temperature variations and remain affordable. 

Resistors, also known as RTDs (Resistance Temperature Detectors), use the change in the electrical resistance of a metal as a function of temperature to provide measurements. There are different types of resistor, each using different metals, which can affect the temperature range that the sensor can measure accurately. The most common metals used for resistors are tungsten, platinum, nickel and copper, each with a different temperature range. Platinum is the most commonly used because its temperature range is the most functional in many HVAC-R situations.