Electricity + Control August 2019

TEMPERATURE MEASUREMENT + INSTRUMENTATION

The advantages of non-contact temperature measurement R&C Instrumentation highlights the advantages of using non-contact thermometers as opposed to thermocouples to measure temperature accurately and consistently in process industries.

1. Infrared thermometers are lower in cost than they were and are becoming smaller in size, with continual innovations and improvements. Take Note! 1

T emperature is one of the most common measurement parameters used for monitoring and control in process industries. In production as well as in quality control and maintenance, temperature represents an important indicator of product quality or equipment condition. While thermocouples are among the most popular temperature measurement devices in industry, there has been a growing shift towards infrared, non-contact thermometers, also known as pyrometers. The reason for this shift can be attributed to the many advantages of using infrared (IR) thermometers. These include:

it were contacted (as with glass or wood, for example, or very small or thin objects). To ensure accurate, repeatable measurements it is important to consider certain conditions: - There has to be direct line of sight between the sensor and the object - The optics of an IR thermometer need to be protected against dust or condensation - IR thermometers measure surface temperatures and the ability to emit thermal radiation depends on the kind of material and especially on the surface finish.

- Fast response time (measured in milliseconds), the user receives more information per time period - The ability to measure objects that move, rotate or vibrate (such as conveyorised production lines or other moving objects) - The ability to measure high temperatures up to 3 000 °C. In such high temperatures contact probes will not work or have a relatively short lifetime - The instrument’s surface is not vulnerable to mechanical damage or contamination, making it suitable for use in food, pharmaceuticals and soft plastics industries, among others - There is no influence on objects with high thermal-conductivity where the object temperature would change if

Non-contact infrared thermometers can measure temperatures up to 3 000°C.

26 Electricity + Control

AUGUST 2019