Sensors & Transducers


Selecting the right infrared sensor

November 2004 Sensors & Transducers Education (Industry)

Since surface temperature is often a good indicator of how well your equipment or process is running, regular temperature measurement should be an essential element in any industrial process control application.

Some considerations to make before choosing an infrared sensor:

* What is the temperature range of the process or maintenance application?

* What type of material is being measured?

* How far away from the process to be measured is the sensor?

* What area of the process needs to be measured?

These are the main questions to ask when choosing the correct Raytek temperature sensor for an application. Environmental and operating conditions, for example ambient temperature, will determine other sensor specifications, such as the need for protective accessories or display and output capability.

Consider target size and distance

Raytek offers a variety of products with specific temperature range features. Single wavelength infrared temperature sensors need a clear line of sight between the instrument and the target. Sighting options allow the user to aim the sensor on the target. Some Raytek units have a built in laser that pinpoints the target, which is very helpful when the target is very small, or in dark inaccessible areas. A two-colour or ratio instrument is most effective when the target is very small or is moving in and out of the field of view. A fibre-optic unit, whose cable can snake around obstructions, is best in a harsh environment or if a direct line of sight between the instrument and the target is otherwise impossible. For single wavelength sensors, the measurement target should be larger than the field of view by at least 50%. If the target is smaller than the field of view, background temperatures will affect the reading.

Consider surface characteristics

The target materials temperature range, emissivity and surface characteristics determine the response or wavelength needed in a sensor. Emissivity is the ability of the material to emit IR energy. Most organic, painted or oxidised surfaces have emissivity values close to 0,95, which is already pre-set in some of the Raytek products. Other Raytek sensors have adjustable emissivity to ensure accuracy when measuring materials outside this value, such as metals, glass and thin film plastic.

R&C Instrumentation is offering free copies of the booklet: Infrared technology, principals of non-contact temperature measurement - and will send this 29-page illustrated booklet by post or e-mail - whichever is preferred. Those wanting a copy should e-mail info@randci.co.za with your name, company, address and contact details - and whether you would prefer e-mail or hard copy.

For more information contact R&C Instrumentation, 032 946 2805, stevee@randci.co.za, www.randci.co.za



Credit(s)



Share this article:
Share via emailShare via LinkedInPrint this page

Further reading:

2D/3D profile sensor for weld seam tracking
ASSTech Process Electronics + Instrumentation Sensors & Transducers
Supporting software can evaluate two- and three-dimensional data from smart cameras, vision systems, profile sensors and IPCs with profile sensors.

Read more...
Standard-compliant differential current transformer
Beckhoff Automation Sensors & Transducers
The SCT5564 can be used as a residual current monitor and can measure DC and AC residual currents with up to 100 kHz frequency in the 0 to 2 A range.

Read more...
Imaging system for slowly rotating kiln shells
R&C Instrumentation Temperature Measurement
The Raytek CS400 system is able to synchronise thermal imaging at speeds as low as 2 revolutions per hour.

Read more...
Wire-actuated encoder for crane arms and lifting platforms
Instrotech Sensors & Transducers
Siko has solved the challenges presented by such applications with the SG 30 and its very compact, yet robust, design.

Read more...
Ultrasonic distance sensor
ASSTech Process Electronics + Instrumentation Sensors & Transducers
Wenglor’s new ultrasonic distance sensors combine low installation depth and easy integration of the sensor with tried and tested ultrasonic technology, setting new standards in terms of range and integration options.

Read more...
Grist for the mill
Turck Banner Editor's Choice Sensors & Transducers
To meet the requirements of Swiss company Bühler with regard to its MHSA grain huller, Turck certified its contactless Li linear position sensor for use in the Ex area. Thanks to its contactless operating principle, the robust sensors are both maintenance-free and wear-free. They offer an impressive performance due to their optimum reproducibility, resolution and linearity over a large temperature range.

Read more...
Vibration pen for hazardous areas
R&C Instrumentation IS & Ex
Vibration and temperature are the most common parameters measured on process plants to predict equipment failure or process problems. As part of the extensive range of vibration measurement products and IS rated instruments from R&C Instrumentation, the TV712 series from Time now comes in IS versions for EX Hazardous areas such as coal mines and chemical plants.

Read more...
Ex-rated strain gauge transducer
Turck Banner Sensors & Transducers
Turck Banner's IMX12-SG for force measurement applications in hazardous areas achieves response times below 10 ms and can be used as a repeater or signal converter.

Read more...
Concentration measurement with process sensors
Sensors & Transducers
To run chemical reactions in an optimal range and to control product quality, online concentration measurement is required. This ensures a fast intervention in case of concentration variation during ...

Read more...
Sensors for pulp and paper applications
Gail Norton Instrumentation Sensors & Transducers
Some of the toughest challenges for sensors are found in the pulp and paper industry. Here, high temperatures and a contaminated environment make it difficult for optical sensors to operate accurately ...

Read more...