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Non-contact temperature measurements using IR thermometers

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Comtest, based in Johannesburg, is a company providing test and measurement, communications, process control equipment solutions and specialised systems from world leading manufacturers to the Southern African market. This article provides information on non-contact temperature measurement using IR thermometers.

 

Comtest, based in Johannesburg, is a company providing test and measurement, communications, process control equipment solutions and specialised systems from world leading manufacturers to the Southern African market. This article provides information on non-contact temperature measurement using infrared (IR) thermometers.

IR thermometers allow the non-contact measurement of surface temperatures by analysing the invisible infrared spectrum emitted from an object.

IR measurement devices, like Fluke’s new VT02 Visual IR Thermometer, make it safe to take surface temperature readings of items like rotating, hard-to-reach, electrically live or dangerously hot targets. For preventative maintenance tasks, they cut the measurement time to almost zero with the ability to take a surface temperature reading in less than one second.

IR thermometers can be used to conduct thousands of different types of measurements, including:
• Electrical – being used to troubleshoot problems with electrical connections and verify uninterruptible power supplies by locating hot spots in the output filters or DC battery connections.
• Preventive maintenance – using IR thermometers for preventive maintenance measurements of hard-to-reach equipment such as HVAC supply diffusers or dangerous equipment like motors, generators and bearings helps to identify potential problems.
• HVAC – sourcing leaks due to faulty ducting.
• Steam – IR thermometers are particularly useful in taking surface temperature measurements of uninsulated steam lines and equipment which pose a large safety hazard due to the potential presence of live steam.
• Food processing – IR temperature measurement is the fastest, most efficient and FDA-recommended method of monitoring food safety along the critical control points in control point (HACCP) standards.
• Fast test of multiple targets – from one location, saving time and money.

Putting IR technology to use is easy, but there are two critical parameters that must be understood to ensure proper and consistent temperature measurements with infrared type devices. They are optical resolution and emissivity.

Optical resolution
Optical resolution refers to the sample area the IR meter is measuring at a given distance. Optical resolution is also referred to as the “distance-to-spot-size ratio” or “field-of-view”.

Know your application! A device with a 4:1 optical resolution cannot effectively be used to measure the temperature of an object 1,5m away – even if the laser beam sight projects that far.
 
Try to determine how you are going to apply the IR thermometer before purchasing, and then buy a tool that provides the appropriate optical resolution for the application and avoid erroneous readings.

Emissivity
Low-cost IR measurement instruments are typically fixed at 0,95 emissivity. To get an effective actual temperature reading, the surface being measured must have an emissivity close to 0,95. In other words, measuring a surface that is not highly reflective will provide an accurate reading. If a 0,95 fixed emissivity IR instrument is used to measure an object that is not close to 0,95, the reading will be incorrect.

Fluke IR thermometers
The Fluke VT02 Visual IR Thermometer is a troubleshooting camera with an infrared heat map. Until now, electricians, industrial, HVAC and automotive technicians had to choose between single-point infrared thermometers and high-resolution thermal imagers (infrared or “IR” cameras).

The Fluke VT02 Visual IR Thermometer fills the gap, for when a single-spot temperature reading isn’t enough and a high-resolution thermal image is more than most users need. This one tool combines the visual insight of a thermal imager, the visual images of a digital camera and the point-and-shoot convenience of an IR thermometer.

Contact Comtest for more information on the new Fluke VT02 Visual IR thermometer.

Comtest
Tel: (011) 608 8520
Website: www.comtest.co.za