Pyrometer for harsh temperature applications

Temperature Measurement

May 2017 Temperature Measurement

Measuring the temperature of reflective metals is a challenge as reflective surfaces, hot furnaces and high ambient temperatures can make it difficult to achieve results with non-contact sensors. Now available from ASSTech is the Calex Fibre-Mini, a fibre optic pyrometer with innovative features for accurate measurement, specific for these applications.

Problems when using a handheld IR thermometer to measure the surface of shiny metals include difficulty to achieve an accurate measurement as changing the angle can affect the reading, or the thermometer cannot display a believable temperature, especially when aiming it into a furnace.

General purpose, long wavelength temperature guns are not suitable to use on metals because they are more susceptible to errors than shortwave sensors if the emissivity setting is incorrect. A small error can cause a big error of measurement.

Add to this the problem that the area surrounding the furnace is a harsh place to mount an infrared sensor, with the ambient temperature commonly exceeding 100°C and this challenging application rules out most choices of sensor.

The solution is to use a shortwave pyrometer such as the Fibre-Mini with the following advantages:

• Fibre-optic sensing head withstands up to 200°C ambient temperature, making it ideal for mounting near furnaces.

• No electronics in the sensor head make it immune to electromagnetic interference in high-EMC applications such as induction heating.

• Reflected energy compensation allows for an accurate reading when measuring reflective objects inside furnaces. Simply enter the temperature of the furnace interior and the sensor will compensate for the reflection for a more accurate reading. This can also be adjusted automatically on Modbus models for maximum accuracy during heating and cooling cycles.

• Laser aiming light illuminates the measurement area, showing both the location and the size of the measuring spot.

• Large, full colour temperature display with data logging makes the Fibre-Mini a truly plug-and-play solution. A choice of 4-20 mA or RS-485 Modbus outputs is available for connection to the process instrumentation.

• Fully configurable via touchscreen with no need for any additional configuration hardware or software.

A choice of temperature ranges from 250°C to 2000°C is available, as is a choice of optics for measuring small or large areas at short or long distances. Feeding the sensing head through conduit and trunking is easy thanks to the slim, highly flexible fibre-optic cable which is available in lengths of 3,5 or 10 m. The short measurement wavelength allows the sensor to measure through many ordinary viewpoints made of glass or quartz as well as specialist IR-transmissive materials.

For more information contact Anastas Schnippenkotter, ASSTech Process Electronics & Instrumentation, +27 (0)11 708 9200, [email protected], www.asstech.co.za

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Temperature Measurement

Pyrometer for harsh temperature applications

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