Considerations When Using An Infrared Thermometer Brochure

Tel: 01530 566800 Fax: 01530 560373 Email: sales@atp-instruments.co.uk CONSIDERATIONS WHEN USING AN INFRARED THERMOMETER There are several considerations to acknowledge when using infrared thermometers – it’s not as simple as some suppliers would have you believe. It’s not point, pull the trigger, read the measurement. Let me explain… All objects have the ability to absorb and emit radiated heat, but at different values. Dull and dark objects such as concrete and rubber, for example, will retain more heat under identical conditions than reflective objects like steel. Infrared thermometers are equipped with sophisticated optics to measure radiated heat. However, there are two important factors that will drastically effect the accuracy of a measured value, the first being laser spot size, the second being emissivity. Let’s deal with laser spot size first… Infrared thermometers measure the temperature of a flat surface area. When an infrared thermometer is equipped with a laser, the laser dot indicates the centre point of the area being measured, not the focal point of measurement. The spot size is the ratio based on the distance from the thermometer to the object being measured. Measurements should be made as near to the object as possible. The thermometer can measure at reasonable distances, but the accuracy of the reading can be affected by external sources such as dust, smoke, steam, and even light. The nearer to the object, the smaller the area of measurement, the greater the accuracy of a reading. It has to be considered, that when taking measurements from a larger distance, the surface spot size could include surface areas not intended to be measured. Now let’s talk emissivity… Emissivity is a term based on an object’s ability to emit radiated heat. The scale is from 0.1 through to 1.0, and takes into account the colour, the surface finish, and the reflective nature of the object being measured. The emissivity value 0.1 is associated with very shiny objects such as steel, whilst 1.0 is the value associated with matt black. Some infrared thermometers feature adjustable emissivity, but it is very difficult for a user to accurately determine the correct value, taking into consideration the whole colour spectrum, and the reflective nature of the object being measured. The error in the accuracy of a measured value can be as much as 30% of the reading just based on emissivity. A simple way to overcome this is to paint a small area of the object being measured matt black. Or, paint a piece of masking tape matt black, and stick it to the surface of the object being measured. Black board paint or an aerosol from a car accessory shop will do. It’s not the thickness of the paint that matters, but it has to be solid in colour. Click here for a quick demonstration. Tel: 01530 566800 Fax: 01530 560373 Email: sales@atp-instruments.co.uk If you can minimise the effects of laser spot size and emissivity on the accuracy of your measurement, you’ll truly be using your infrared thermometer to its full potential. ATP Instrumentation has a wide range of thermometers available designed to suit your individual requirements. If you have a technical query, please call us now on 01530 566800, and we’ll refer you to our instrument technical team.