Pyrometers and contact thermometers are both devices used to measure temperature, but some key differences make each device more suitable for certain applications.
A pyrometer measures the infrared (IR) radiation given off by an object from a distance and is, therefore, able to measure temperature without contact, whereas a contact thermometer directly measures temperature by making physical contact with the object. It is important to consider these differences when choosing a temperature measurement device and select the one that best suits the intended application.
Why Choose a Pyrometer Over a Contact Thermometer?
Pyrometers have many advantages over contact thermometers. The main difference is that pyrometers measure temperature without contact and are suitable for applications where remote sensing is required. This means they are suitable for more types of applications and can measure hot, moving objects in harsh industrial environments.
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Pyrometers Have An Extremely Fast Response Rate
Pyrometers respond instantly to rapid changes in temperature, which makes them suitable for applications where the object’s temperature is changing quickly or the object is fast moving and it is required to accurately track temperature changes.
Contact thermometers are not suitable for measuring moving objects, which is a common requirement in many industrial processes or production lines. They must first reach the temperature of the object at the point of contact to obtain a correct reading, which means they have a much slower response time.
Pyrometers Can Measure the Temperature of Objects from a Distance
A pyrometer measures an object’s temperature from a distance and it is this remote sensing ability that makes them so useful when measuring extremely hot objects. As a pyrometer measures from a distance, it can be located in a safe, cool environment, protecting the device from extreme temperatures and therefore ensuring reliable operation.
Pyrometers Don’t Affect the Temperature of the Object Being Measured
Pyrometers can measure the temperature of an object without influencing it. This is a big advantage, particularly when measuring small objects or thin materials where a contact thermometer directly affects the temperature of the object by drawing heat from the object by thermal conduction.
What Are the Advantages of a Contact Thermometer Compared to a Pyrometer?
For some applications, a contact thermometer is easier to install, for example, for applications measuring temperature in fluids or gasses.
Comparing a Pyrometer to a Contact Thermometer
This table summarises the main differences between a pyrometer and a contact thermometer, so you can decide which is best for your application.
Feature | Pyrometer | Contact Thermometer |
Response time | Pyrometers react very quickly to changes in the object’s temperature. A typical response time is only 1-2 ms or even 0.1 ms for high-end models. | Contact thermometers take longer to measure the temperature of an object, as they have to make contact with the object and wait for the temperature to reach the same temperature through thermal conduction. The typical response time is 1-10 seconds. |
Influence or change the object’s temperature? | Being non-contact, pyrometers do not influence the object’s temperature. | For certain applications, the contact probe can change the temperature of the object. |
Suitable for extremely hot objects? | Yes. Non-contact pyrometers can measure objects up to over 3000°C. | No, contact thermometers usually have much lower temperature limits and their operating life can be reduced for higher-temperature applications. |
Aggressive materials | Being non-contact, aggressive materials can be measured without damaging the pyrometer. | Contact thermometers can be damaged by some types of aggressive materials. |
Remote sensing | Pyrometers can measure the temperature from a distance in areas of extreme heat such as furnaces or kilns. They can be located at a distance in a safe and cool location. | Contact thermometers will be damaged by extreme temperatures and are not suitable. |
Accuracy | Pyrometers are very accurate for a wide range of applications and do not influence the temperature of the object and have a much faster response time. | Contact thermometers are very accurate for some applications, but for specific applications, they can influence or change the temperature of the object they are measuring, making them a poor choice. |
Learn More about Pyrometers
In summary, pyrometers have many advantages over contact thermometers, making them a better choice for many industrial or scientific applications, particularly where remote sensing is required, there are very hot temperatures or fast response time is required. You can learn more about pyrometers by using the links below:
- Learn what a pyrometer is
- Learn more about how a pyrometer works
- Learn more about the different types of pyrometers
- Learn more about what information you need to select the correct pyrometer
- Learn more about spot size when selecting a pyrometer
Visit our temperature measurement and thermal processing page to learn more about LIMAB UK’s temperature measurement products, including pyrometers. To speak to a product specialist to find out how a pyrometer could benefit your company, call +44 (0)1823 668633.