Thermometers can lose accuracy over time due to various factors such as aging, mechanical shock, environmental changes, and human error. Therefore, it is essential to calibrate thermometers regularly to ensure their reliability and accuracy. The U.S. Food and Drug Administration (FDA) requires that all inspection, measuring, and test equipment, including thermometers, be routinely calibrated, inspected, checked, and maintained. The FDA also mandates that calibration standards used for inspection, measuring, and test equipment be traceable to national or international standards.
About Thermometer Calibration
Thermometer Calibration is the process of comparing a thermometer’s readings with a known reference standard and adjusting the thermometer if necessary. There are different types of thermometers that require different methods of calibration. In this blog post, we will discuss some of the common types of thermometer calibration and their advantages and disadvantages.
There are two methods widely used for calibrating thermometers:
- Fixed points calibration: A thermometer is calibrated by taking readings at specific temperature reference points, such as freezing or melting points, triple points, or vapor pressure points of pure substances. This is done by placing the thermometer in a fixed point cell that maintains the desired temperature. The fixed points method is the most precise calibration technique, but it’s complex and costly, so it’s not commonly used by calibration laboratories. It’s generally reserved for the highest quality calibrations.
- Comparison to standard thermometers: The comparison method is the most popular calibration technique, which involves comparing the thermometer under test with a higher accuracy standard thermometer. This comparison typically occurs in a liquid bath or dry block calibrator. The parameters to consider include immersion depth and the homogeneity of the liquid or air where the thermometer is placed. Immersion depth depends on the thermometer’s construction and temperature differences, while better homogeneity is achieved in liquid baths but can be improved in dry block calibrators with an equalizing block.
Temperature Calibration
Temperature NIST calibration offers calibration of various types of thermometers using high-quality equipment and standards. Accurate temperature calibration can provide traceable certificates that document the calibration results and comply with international standards and regulations.
Some of the benefits of temperature calibration are:
- Ensures the accuracy and reliability of thermometers across a wide range of temperatures and applications.
- Reduces the risk of errors and failures that can affect product quality, safety, and performance.
- Saves time and resources by outsourcing the calibration process to experts who have the necessary skills, equipment, and experience.
Digital Calibration
Digital NIST calibration is a method of calibrating digital thermometers using a device called a digital thermometer calibrator, an instrument that generates precise and stable temperatures that can be used as reference points for digital thermometers. This type of calibration can be performed by following these steps:
- Connect the digital thermometer to the digital thermometer calibrator using a suitable probe or adapter.
- Set the digital thermometer calibrator to the desired temperature point and wait for it to stabilize.
- Compare the reading on the digital thermometer with the reading on the digital thermometer calibrator and note any difference or error.
- Adjust the digital thermometer if necessary, using its calibration function or software.
Some of the benefits of digital calibration are:
- Easy and convenient to perform as it does not require any additional equipment or standards.
- Fast and accurate as it uses precise and stable temperatures generated by the digital thermometer calibrator.
- Versatile and flexible as it can calibrate different types of digital thermometers with various ranges and resolutions.
Humidity Calibration
Humidity NIST calibration is a method of calibrating hygrometers, which are devices that measure humidity or moisture content in air or other gases. This type of calibration can be performed using two main techniques: relative humidity calibration and dew point calibration.
Relative Humidity Calibration
Relative humidity calibration is a technique that uses a device called a humidity chamber, which is a sealed enclosure that maintains a constant temperature and humidity level. This type of calibration can be performed by following these steps:
- Place the hygrometer inside the humidity chamber and close it securely.
- Set the humidity chamber to the desired humidity level and wait for it to stabilize.
- Compare the reading on the hygrometer with the reading on the humidity chamber and note any difference or error.
- Adjust the hygrometer if necessary using its calibration function or software.
Dew Point Calibration
Dew point calibration is a technique that uses a device called a dew point generator, which is an instrument that produces a stream of gas with a known dew point temperature. This type of calibration can be performed by following these steps:
- Connect the hygrometer to the dew point generator using a suitable tubing or adapter.
- Set the dew point generator to the desired dew point temperature and wait for it to stabilize.
- Compare the reading on the hygrometer with the reading on the dew point generator and note any difference or error.
- Adjust the hygrometer if necessary using its calibration function or software.
Some of the benefits of humidity calibration are:
- It ensures the accuracy and reliability of hygrometers across a wide range of humidity levels and applications.
- It reduces the risk of errors and failures that can affect product quality, safety, and performance.
- It saves time and resources by outsourcing the calibration process to experts who have the necessary skills, equipment, and experience.
Infrared Calibration
Infrared NIST calibration is a method of calibrating infrared thermometers, which are devices that measure temperature by detecting the infrared radiation emitted by an object. This type of calibration can be performed using a device called an infrared calibrator, an instrument that emits a known amount of infrared radiation that can be used as a reference point for infrared thermometers. Infrared calibration can be performed by following these steps:
- Align the infrared thermometer with the infrared calibrator using a suitable mount or stand.
- Set the infrared calibrator to the desired temperature point and wait for it to stabilize.
- Compare the reading on the infrared thermometer with the reading on the infrared calibrator and note any difference or error.
- Adjust the infrared thermometer if necessary using its calibration function or software.
Some of the benefits of infrared calibration are:
- It is easy and convenient to perform as it does not require any contact or immersion of the thermometer in a medium.
- It is fast and accurate as it uses precise and stable temperatures generated by the infrared calibrator.
- It is versatile and flexible as it can calibrate different types of infrared thermometers with various ranges and resolutions.
Liquid-in-Glass Calibration
Liquid-in-glass NIST calibration is a method of calibrating liquid-in-glass thermometers, which are devices that measure temperature by observing the expansion or contraction of a liquid in a glass tube. This type of calibration is performed using a liquid-in-glass calibrator. This instrument provides a controlled environment for immersing and comparing liquid-in-glass thermometers. Liquid-in-glass calibration is done by following these steps:
- Place the liquid-in-glass thermometer inside the liquid-in-glass calibrator and secure it firmly.
- Set the liquid-in-glass calibrator to the desired temperature point and wait for it to stabilize.
- Compare the reading on the liquid-in-glass thermometer with the reading on a reference thermometer and note any difference or error.
- Adjust the liquid-in-glass thermometer if necessary using its calibration function or software.
Some of the benefits of liquid-in-glass calibration are:
- It is simple and reliable as it uses a direct comparison of two thermometers in the same medium.
- It is inexpensive and portable as it does not require any sophisticated equipment or standards.
- It is compatible and universal as it can calibrate most types of liquid-in-glass thermometers with various ranges and resolutions.
Conclusion
Thermometer calibration is an important process that ensures the accuracy and reliability of thermometers in various applications. There are different types of thermometers that require different methods of calibration. Each method has its own advantages and disadvantages. Some of the common types of thermometer calibration are temperature calibration service, digital calibration, humidity calibration, infrared calibration, and liquid-in-glass calibration. By understanding these types and methods, you can select the best option for your needs and expectations.