How to Prevent Vibration Damage to Thermocouples and RTD Sensors

May 7, 2020

All thermocouples use the Seeback effect. This means that when you put two materials that are different together, an electromagnetic force is generated. The two metals together are used to measure changes in temperature. Thermocouples have an extensive use in industry, especially with machinery when they must operate at a specific temperature. Because these pieces of equipment must operate at a particular temperature, thermocouples and RTD sensors are essential, and if they are damaged, they are not functioning properly. Many times, these delicate pieces of equipment are damaged because of vibration. How do you prevent damage to both thermocouples and RTD sensors?

How Do Thermocouples Protect Against Vibration?

Often, thermocouples are covered with a protected metal sheath. That sheath helps to protect the thermocouple from vibration damage. If the thermocouple is housed within a metal sheath, there is much less chance of vibration. However, there are times that the thermocouple is left unguarded or exposed in order to improve the time of response. Sometimes, this creates problems with vibration. There may also be an issue if the thermocouple is grounded close to machinery or other equipment, especially if there is a lot of noise.

Sensors often are wire wrapped or wrapped in a thin film. There are some sensors with a glass core, which are mainly used to measure liquids. If the sensor is wrapped in a thin film, it is better protected than a wire-wrapped sensor. It also gives them more sensitivity to changes in temperature.

How Do Thermcouples and Sensors Become Damaged?

The main way that thermocouples and sensors become damaged is usually due to vibration fatigue. When these pieces become damaged, the insulation fails and the thermocouple could short circuit. You will know there is a damaged thermocouple when you begin to see abnormally high readings. The thermocouple could also become uncalibrated due to vibrations. This is important, because if a thermocouple isn't calibrated, it isn't reading temperatures correctly. If you have an RTD that is wired, they are susceptible to damage due to vibration. When RTDs are damaged, you may get an open circuit instead of a closed one and you might also get abnormally high temperature readings.

How Can Thermocouples and Sensors Be Protected Against Vibration Damage?

One way to protect thermocouples and sensors against vibration damage is to purchase thermocouples and sensors that have extra protection against vibration damage. In many cases, these sensitive instruments are protected by an additional coil that helps to minimize vibrations, and helps them last longer.

Also, you can work to minimize damage to thermocouples and sensors by grounding them wherever possible. Often these pieces are damaged due to static electricity, and grounding them prevents this problem. You can also choose to check thermocouples and sensors regularly for vibration damage to make sure they are still properly calibrated. Constant reading of temperature will also help you determine if there is a problem with vibration in the machinery that is affecting your sensors or thermocouples. By making sure that the thermocouples and sensors are functioning correctly, you'll ensure your equipment or machinery is functioning at the right temperature.