Temperature is the degree of hotness or coldness of a substance measured on a definite scale. Temperature is measured when a measuring instrument, such as a thermometer, is brought into contact with the medium being measured. All temperature-measuring instruments use some change in a material to indicate temperature. Some of the effects that are used to indicate temperature are changes in physical properties and altered physical dimensions. One of the more important physical properties used in temperature-measuring instruments is the change in the length of a material in the form of expansion and contraction.
A time temperature indicator (TTI) is a device or smart label that shows the accumulated time-temperature history of a product.[1] Time temperature indicators are commonly used on food, pharmaceutical, and medical products to indicate exposure to excessive temperature (and time at temperature).
RTD’S Resistance thermometers, also called resistance temperature detectors (RTDs), are sensors used to measure temperature by correlating the resistance of the RTD element with temperature. Most RTD elements consist of a length of fine coiled wire wrapped around a ceramic or glass core.
Temperature gauges are instruments used to measure the temperature of a fluid or a gas. They are commonly used in industrial process control, heating and ventilation systems, power plants, and many other applications.