What Is a Thermometer Probe?
A thermometer probe is a metal sensor, integral to a thermometer, used for measuring temperature by contacting the substance (like a liquid). There are two main types: contact and non-contact thermometers. Non-contact models measure temperature based on infrared radiation and are classified into thermal and quantum types. Contact types include thermistors, resistance thermometers, thermocouples, and mercury/alcohol thermometers.
Uses of Thermometer Probes
Thermometer probes, connected to the thermometer, have varied measurement ranges depending on their type. Thermistors measure from -50°C to 300°C, resistance thermometers from -200°C to 800°C, and thermocouples from -200°C to 2000°C. Their slender design allows for temperature measurements in various contexts, such as checking the temperature of liquid products in food factories or measuring the internal temperature of frozen meat.
Principles of Thermometer Probes
Each thermometer probe type operates on a different principle:
- Thermistors: Utilize semiconductor properties where resistance changes significantly with temperature. They are sensitive but may lack accuracy and are vulnerable to shock. NTC types are common for temperature measurement, while PTC types are used for constant temperature sensors.
- Resistance Thermometers: Typically use platinum due to its linear relationship between resistance and temperature. Platinum offers stability and a wide temperature range but is costly and responds slowly.
- Thermocouples: Operate on the Seebeck effect, where thermoelectromotive force is generated when two different metals are joined and their junctions are at varying temperatures. They are cost-effective, fast-responding, accurate, and capable of measuring high temperatures. Common metal combinations include nickel-chromium and nickel-aluminum alloys, and platinum-rhodium with platinum.