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Choosing a Bimetal Thermometer: 5 Factors to Consider

Product Selection | Bimetal Thermometers

If your process requires accurate and reliable temperature readings to ensure the protection of your equipment and its operators, you need to use the right bimetal thermometer. If you don’t, you could risk damage to your instrumentation that can bring your business to a halt.

But how do you know if you’ve chosen the best bimetal thermometer for your application?

There are many factors to consider when choosing one. This article will discuss some of the more important considerations so you can be better prepared to select a high-quality bimetal thermometer.

High-Quality Bimetal Thermometers

To make sure you have a bimetal that’s best suited for your process, you should first ensure that it’s high quality. A quality bimetal thermometer must be hermetically sealed, which prevents fogging from happening inside the case.

The bimetal should also be easy to read, the temperature range should meet the requirement of your application, and it should have ±1% of span accuracy, traceable to the National Institute of Standards and Technology (NIST).

Let’s discuss other factors to consider when selecting a bimetal thermometer.

5 Considerations when Choosing Bimetal Thermometers

When researching for your specific application, keep these factors in mind:

  1. Size
    You need to make sure that your bimetal thermometer is the right size for the application so that you can view the temperature from all angles. You will need a larger dial size to be able to read it from far away. Options include 2 inches, 3 inches and 5 inches.

  2. Connection
    The type of connection the bimetal has, or how you need to mount it to see it properly, is also a consideration. Is it rear connected? Or does it have a lower connection? There are also “every angle” thermometers. This type of bimetal allows you to view the temperature from every angle no matter where it’s mounted because the dial rotates 360 degrees.

  3. Material
    What is the bimetal thermometer made of? Although 304 stainless steel is the norm, 316 stainless steel is sometimes required for certain ambient conditions. Also, consider if you need a plastic dial window or shatterproof safety glass.


  4. Liquid Fill
    In vibration applications, silicone liquid fill can prolong instrument life. Liquid-filled thermometers operate in ranges from -40 degrees F to 550 degrees F (-40 to 300 degrees C), so this might be a good option if your process experiences vibration.


  5. Tamper-Proof vs. Externally Adjustable
    Bimetal thermometers come in externally adjustable or tamper-proof designs. If you need to check and recalibrate the thermometer in the field, an externally adjustable thermometer works. But a tamper-proof unit has no adjustment, meaning it can avoid any tampering with the temperature indication.

We don’t like to pressure you, but we have more information.

Now that you understand the factors to consider when selecting a bimetal thermometer, you should be able to find the best one for your application. Ashcroft’s bimetal thermometers and gas actuated thermometers provide easy-to-read temperature measurement on a dial indicator. Both operate without the use of mercury.

Always be sure that you’re using a thermowell in your application to protect your bimetal thermometer from high pressure or corrosion.

Read one of our other temperature instrument articles to learn more:

You can also reach out to our specialists here at Ashcroft if you have questions about temperature measurements or instrumentation.

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About Bob Divita, Director NA Channel Sales

Bob DiVita is the Director of North America Channel Sales here at Ashcroft. Bob has over 40 years of experience at Ashcroft working in many roles ranging from Technical Support, Product Management for Mechanical Pressure & Temperature Instruments and his current role, which is focused on our Channel Partners in North America.