Bimetal thermometers are incredibly common and widely used due to their simple design and relatively accurate readings. However, it’s important to know when to calibrate them to ensure their accuracy. In this article, we will explore why and when you should calibrate your bimetal thermometer.
Table of Contents
Understanding How Bimetal Thermometers Work
Bimetal thermometers work by converting temperature changes into mechanical movements. Inside the stem of the thermometer, there is a bimetallic strip made of two different metals, such as copper, brass, or steel. As the temperature increases or decreases, the two metals expand or contract at different rates, causing the strip to bend. This movement is then visually indicated on the dial of the thermometer, providing temperature readings.
The Importance of Calibration
Calibration is the process of ensuring that a thermometer is accurate. By comparing the readings of a bimetal thermometer to a known temperature source, you can adjust the thermometer to ensure its accuracy. Calibration is crucial when precise temperature measurements are required. For more information on temperature calibration, check out our recent blog post on the 4 common questions about temperature calibration.
When to Calibrate Your Bimetal Thermometer
There are several situations when it is recommended to calibrate your bimetal thermometer:
1. The Thermometer is New
If you have recently purchased a bimetal thermometer from a supplier or manufacturer you are not familiar with, it is wise to check its accuracy. However, if the thermometer comes with a valid calibration report, indicating its accuracy and when it was tested, you can skip this step.
2. The Thermometer Was Dropped
Even a small fall can affect the accuracy of a bimetal thermometer. If you or someone else accidentally dropped the thermometer, it’s a good idea to check if the accuracy is still intact.
3. Switching Temperature Ranges
If you have been using the thermometer within a specific temperature range for an extended period, and you now need to switch to a different range, calibration is recommended. A significant difference between the old and new temperature ranges can affect the thermometer’s sensitivity and accuracy.
4. Long-Term Storage
If the thermometer has been sitting on a shelf for an extended period, it may become less sensitive to temperature changes. Before using it, calibrate the thermometer to ensure its accuracy.
5. Suspected Inaccuracy
If the thermometer’s readings do not align with your expectations or other temperature sources, it’s a clear sign that calibration is necessary. For example, if your room’s AC is set to 21°C, but the bimetal thermometer shows 24°C, calibration is needed.
How to Calibrate Your Bimetal Thermometer
Calibrating a bimetal thermometer is a simple process. Start by setting up a glass or bucket filled with ice and add cold water until it’s completely filled. Let it sit for a few minutes, and then insert the thermometer. Make sure the stem is fully submerged in the water to prevent any influence from surrounding air. Wait for the indicator to settle down and ensure it reads 0°C. If it doesn’t, adjust the nut located on the back of the dial until it indicates 0°C. Once done, your thermometer should be as accurate as possible without using calibrated equipment.
If you have strict requirements for your thermometer’s accuracy, you may consider more precise temperature calibration. Check out our other article on the 4 main steps to calibrate temperature instruments for further information.
Now that you have calibrated your thermometer, you may notice that the response time is lacking. If you’re seeking a solution to this issue, head over to our blog post on the response time differences between gas-actuated and bimetal thermometers. Discover whether upgrading to a gas-actuated thermometer is the right choice for you.
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