Temperature sensors are prevalent in everyday household appliances such as refrigerators, microwaves, water heaters, and thermometers. They are also used in many fields, including geotechnical monitoring, railroad tracks, bridges, and concrete construction. Temperature sensor calibration involves a reliable, reproducible, and documented comparison of the tested sensor or data logger with reference equipment. In this blog, we will discuss the role of temperature sensors and what makes them an inevitable part of your laboratory.
What are the temperature sensors?
A temperature sensor, such as a thermocouple or resistance temperature detector, measures temperature and outputs the data as an electrical signal.
The simplest type of temperature meter is a thermometer, which measures heat levels and indicates degrees of hotness or coolness. Temperature meters are crucial in monitoring concrete, structures, soil, water, and bridges in the geotechnical field. They help detect structural changes caused by seasonal variations.
A thermocouple (T/C) consists of two different metals that produce an electrical voltage proportional to changes in temperature. In contrast, a Resistance Temperature Detector (RTD) is a variable resistor that alters its electrical resistance precisely, repeatably, and nearly linearly in response to temperature changes.
What do temperature sensors do?
Temperature sensor calibration involves a reliable, reproducible, and documented comparison of the tested sensor or data logger with reference equipment. The referenced instrument is highly precise and undergoes regular inspections in an accredited laboratory. Calibration occurs at defined measurement points. First, a device or machine maintains stable conditions using a bath or dry block. The hardware then adjusts over a set interval, usually thirty minutes, to reach the target temperature.
A temperature sensor measures an object’s degree of hotness or coolness. Its operation relies on the voltage across a diode, with temperature changes directly affecting its resistance. As the temperature decreases, resistance diminishes, and vice versa.
The resistance measured across the diode is converted into readable temperature units (Fahrenheit, Celsius, etc.) and displayed numerically. In geotechnical monitoring, these temperature sensors are essential for measuring the internal temperature of structures such as bridges, dams, buildings, and power plants.
What are the functions of temperature sensors?
There are various temperature sensors, but they are commonly categorized based on their mode of connection: contact and non-contact sensors.
Contact sensors, such as thermocouples and thermistors, measure temperature by directly contacting the object. In contrast, non-contact temperature sensors assess the thermal radiation emitted by a heat source, making them suitable for hazardous environments like nuclear and thermal power plants.
In geotechnical monitoring, temperature calibrators measure the heat of hydration in mass concrete structures and monitor groundwater migration. They are vital during the curing process of concrete, which requires a relatively warm environment to set and cure properly. Additionally, seasonal variations can cause structural expansion or contraction, affecting the overall volume of the structures.
How does a temperature sensor work?
The basic principle behind temperature sensors involves the voltage across the diode terminals: as voltage increases, so does temperature, which leads to a voltage drop between the base and emitter terminals of the transistor.
The vibrating wire temperature meter operates on the principle that dissimilar metals have different linear coefficients of thermal expansion. It consists of a high-tensile-strength wire stretched between two fixed metal points. Any temperature change alters the tension in the wire, affecting its natural vibration frequency.
In the Encardio Rite temperature meter, the dissimilar metal used is aluminium, which has a higher coefficient of thermal expansion than steel. As the temperature changes, this variation is converted into a frequency signal. A similar readout unit is used for other vibrating wire sensors that can be utilised to monitor temperature effectively and efficiently.
Temperature changes are sensed by the specialised Encardio Rite vibrating wire sensor, which converts the information into an electrical signal transmitted as a frequency to the readout unit.
Conclusion
Temperature calibrators assist our clients in several ways, which are essential for safety and quality control, aiding companies in adhering to industry regulations and standards. Frequent calibration can help in detecting problems with instruments early on, possibly averting equipment failure and prolonging its life, guarantees the accuracy of information gathered from operations or experiments that are temperature-sensitive, by displaying a dedication to quality and dependability, maintaining calibrated instruments can increase consumer confidence in goods and services.
Partner with Nagman Instruments to maintain accuracy, compliance, and safety with our precise temperature calibration. We offer various calibration services to help you gain trust among your patrons. Please feel free to contact us today for a quote.
Also Read: Guidelines on the Calibration of Temperature Indicators and Simulators
