Some temperature readings require more precision than a standard thermometer can provide. A device called a resistance temperature detector (RTD) probe measures electrical resistance to deliver highly accurate data.
But what is an RTD sensor probe, and how does a resistance temperature detector work?
RTD probes measure temperature by tracking changes in electrical resistance. A small current flows through a fine coil wrapped around a ceramic or glass core and encased in a protective sheath. Because resistance increases predictably with temperature, you can use these measurements to calculate thermal values. While manual calculations are possible, most RTD probes pair with instrumentation that automatically converts resistance into precise temperature readings based on the International Temperature Scale of 1990 (ITS-90).
There are two common types of RTD designs — thin-film RTDs and wire-wound RTDs. These names describe the nature of the element used in the probe.
There are also less widely used RTD probe designs, such as a coiled RTD.
A thin-film RTD has an element that consists of a thin metal layer, often platinum, set on a ceramic substrate. These RTDs are cost-effective and vibration-resistant. Thanks to their durability, low production cost and flat design, thin-film RTDs are excellent for consumer electronics and general industrial use.
A wire-wound RTD consists of a metal wire, typically platinum, coiled around a ceramic or glass housing known as a bobbin. In general, glass bobbins are better for measuring the temperature of liquids, while ceramic bobbins are better for accurately measuring extreme temperatures.
Wire-wound RTDs provide a higher level of accuracy than thin-film RTDs. However, this comes at a price, as wire-wound RTDs are more expensive and sensitive.
The element in a thin-film or a wire-wound RTD is usually one of three metals.
Many industries rely on RTD probes, from food production and pharmaceuticals to aerospace and manufacturing. They ensure quality, safety and consistency in everyday goods and materials by delivering precise temperature measurements.
RTD probes monitor critical restaurant equipment like ovens, dishwashers, refrigerators and freezers. These sensors track how quickly machines heat up or cool down, helping staff maintain safe food storage and cooking conditions. RTD sensors provide accurate data that supports food safety and reduces the risk of contamination.
RTD probes in manufacturing plants maintain safe working conditions by monitoring ambient temperatures and airflow. In ductwork systems, they keep circulated air within acceptable ranges, protecting employees and equipment from heat-related damage.
RTD probes monitor industrial ovens, freezers and other temperature-sensitive equipment used in large-scale food production. Accurate readings prevent spoilage and ensure food safety. These sensors also support cold-chain logistics by maintaining proper temperatures in transport vehicles, so cargo arrives fresh, safe and usable.
RTD sensors can monitor engine, air and fluid temperatures.
RTD sensors in the chemical industry ensure systems and chambers remain at a safe temperature during processes and testing.
Regular calibration ensures RTD probes continue performing reliably. Variables like vibration, mechanical stress, residue buildup and temperature extremes can all affect how often you should calibrate. Establishing a consistent schedule ensures correct readings over time.
Calibration involves comparing the probe’s resistance measurements against known standards, such as those provided by a precision calibration bath or drywell. This process allows you to verify accuracy and adjust to maintain performance.
After reading this guide, you should know what an RTD sensor is, how it works and when you need one.
Whatever you use your RTD probe for, you’ll want it to be reliable and accurate. Garber Metrology can calibrate your probe thanks to our temperature and humidity calibration services. We’re ISO 9001 Registered by NQA, and ISO/IEC 17025 and ANSI/NCSL Z540-1-1994 Accredited by ANAB, meaning our procedures and standards are of the highest quality.
To find out how we can calibrate your RTD probe, get in touch with us today.
