How do you Calibrate Temperature Measuring Instruments?

As industry expert Process Parameters explains (https://www.processparameters.co.uk/temperature-calibration/), devices used to measure temperature can malfunction sometimes. In such cases, the malfunctioning device will give inaccurate readings, hindering the whole objective of measuring temperature. Due to this, it is essential to periodically check them to verify if it continues to display the required accuracy.

There are temperature measuring instruments like liquid-glass thermometers that are non-adjustable. In this case, the device performance is recorded, and a decision on whether it is fit for its purpose. But for the adjustable device, they should be returned to acceptable measurements in case of inaccuracy.

So, what are some adjustable temperature measuring devices? Below are these adjustable temperature devices;

• Bimetal or spring-type thermometers. They are widely used despite their inaccuracy since they are cheap
• Thermocouples. They are widely used industrial sensor that produces a voltage proportional to temperature
• Resistance –temperature detectors (RTDs). They are very accurate and give a rapid response but are expensive
• Thermistors. On most occasions, they are used in medical applications since they measure temperature over a limited range
• Infrared (IR) radiation detectors. There are two types of IR detectors; pyrometers and thermal imaging cameras. They measure surface temperatures

But how do you calibrate temperature measuring instruments? Continue reading the article to answer this question.

How to Calibrate Temperature Measuring Instruments

Depending on the application of the instrument, you can calibrate temperature devices using two methods. Below is an illustration of these two methods;

Thermal Calibration

This method involves measuring temperature directly, and it is subdivided into two ways;

The Comparison Method

This method compares the thermometer readings under test to an accurate standard thermometer. A thermometer under calibration is inserted into a known, controlled temperature source, and its reading is compared to a reference thermometer.

The Fixed Point Method

In this method, a comparison is not needed since absolute temperatures are given by fixed point cells. Examples of fixed point temperature are; freezing/melting point, triple points, or vapor pressure point.

The second method of temperature device calibration, depending on its application, is electrical simulation.

Electrical Simulation

As the name suggests, this method uses electrical signals, which are voltage or resistance, to simulate temperature probes.

The method is consistent with thermocouples, where voltage signals are precisely generated to a temperature indicator that you can calibrate or adjust.

You can efficiently perform simulation temperature calibration using simulators. Simulators vary depending on their; type (voltage or resistance simulators), accuracy, and package (laboratory, outdoor or explosive area simulators).

Simulators are easy to use since there is no calculation needed. You only have to set the desired temperature, and the electrical signal is generated automatically. However, these calibrations must be performed by credited calibration laboratories with appropriate reference equipment and properly established measurement procedures.

So, How do you Calibrate Temperature Measuring Instruments?

Calibration of temperature devices is essential because it is not just measuring temperature; you also want to measure it accurately. For you to achieve accurate readings, you should do calibrations.

So, how do you calibrate temperature measuring instruments? By using either of the above-illustrated methods; thermal calibration and electrical simulation.

The two methods of calibration are equally reliable. Therefore, to decide which one to use, you may want to consider the operational properties of the temperature instruments you are testing.