kosketuslämpömittaus

Kosketuslämpömittaus, known in English as contact thermometry, is a method of measuring temperature that involves direct physical contact between a temperature sensor and the object whose temperature is to be determined. This is in contrast to non-contact methods like infrared thermometry.

The most common instruments used in contact thermometry are thermometers. These can be based on various physical principles, including the thermal expansion of liquids (like mercury or alcohol thermometers), the change in electrical resistance of a material with temperature (resistance thermometers, such as RTDs), or the generation of a voltage proportional to temperature at the junction of two dissimilar metals (thermocouples). Bimetallic strip thermometers also utilize differential expansion of metals.

For accurate kosketuslämpömittaus, it is crucial that the sensor reaches thermal equilibrium with the object being measured. This means allowing sufficient time for heat to transfer between them. Factors such as the thermal conductivity of both the object and the sensor, the surface area of contact, and the surrounding environment can influence the time required to reach equilibrium and the accuracy of the measurement. The sensor should also be in good thermal contact with the object, often facilitated by thermal paste or a clamping mechanism.

Kosketuslämpömittaus is widely used in various applications, including industrial process control, medical devices (e.g., oral or rectal thermometers), laboratory experiments, and everyday life for checking cooking temperatures or room temperatures. Its main advantages are generally its simplicity, relatively low cost, and high accuracy when properly implemented. However, it is not suitable for measuring the temperature of moving objects, very hot surfaces, or in situations where physical contact could be hazardous or contaminate the object or sensor.