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SA Instrumentation & Control Buyers' Guide

Technews Industry Guide - IIoT 2018

Technews Industry Guide - Maintenance, Reliability & Asset Optimisation


Intrinsically safe
February 2009, Temperature Measurement

After time, temperature is the second most measured physical unit in production. Temperature is an important indicator of product quality, safety and equipment conditions.

Infrared thermometers in industry

During the last five years the IR sensor market has seen two major trends. Firstly, IR thermometers are significantly lower in cost. The most expensive parts of an infrared thermometer are the lenses and detectors. New lens materials and technologies and mass production of IR detectors for consumer products such as toasters, hair dryers and ear-thermometers, have resulted in lower prices for these two important components.

Secondly, IR sensors are becoming smaller in size. In the past, the measurement of low temperatures made it necessary to use fast (low F number) lenses with relatively large diameters in order to capture enough emitted energy. Progress in detector technology and the use of micro system techniques together with improved preamplifier designs have helped reduce the dimensions of the IR-sensing head dramatically. Because the newer sensors have better response characteristics they require less energy to achieve a usable signal, resulting in smaller lens diameters.

Detector and optics

There are two main groups of detectors found in IR thermometers – thermal and photoelectric or photon detectors.

Thermal detectors change their own temperature in response to heat radiated from the process under measurement. Similar to a thermocouple, this produces a corresponding voltage fluctuation proportional to the change in temperature.

Photoelectric detectors (eg, photo diodes) react to the level of photon bombardment which causes a variation in the current flowing through the device.

Thermal detectors respond less quickly than the photoelectric detectors because they have to feel a temperature change. In the case of thermal detectors slow means time constants in the millisecond range compared to nano or microseconds for photoelectric detectors.

Choosing the correct IR unit

Selecting a device with the correct operating wavelength for the temperature under measurement has a significant influence on the accuracy of the results. It is best to use the shortest possible wavelength and Figure 1 indicates the common wavelengths used with respect to target temperature and error. From this it can be see that to measure above 900°C users should not use the common 8-14 micron types, but should rather opt for a 1 or 2 micron wavelength.

Figure 1
Figure 1

Trends in electronic design

Due to the increasing expectations of users and competition among manufacturers, infrared thermometers are continually being improved and electronic design is an area that has seen the most improvements recently.

Process industries continue to need sensors with higher accuracy and repeatability as they look for ways to cut costs, maximise their production lines and monitor quality. Easy installation, use and maintenance continue to be important, as does the ability to withstand harsh environmental conditions. Field checking and field calibration features are becoming more and more important as companies look to optimise their personnel and equipment resources. Manufacturers need IR sensors with a wide operating temperature range that cover more applications and eliminate the need for cooled housings, to keep the costs down.

Manufacturers are taking advantage of the many developments in other industries to continue to expand the capabilities and efficiencies of the IR thermometer. These advances have made a variety of products readily available and affordable where previously they were only used for specific military applications because of the associated cost.

Advances in the cost/performance ratio of detectors and optics are helping expand the applications where IR can be used effectively and yield a better return on investment. Two colour or ratio measurement and units with built in visual cameras are some of the most recent advances.

Supplied By: R&C Instrumentation
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Further reading:

  • Paper mill saves with IR window program
    December 2018, R&C Instrumentation, Maintenance, Test & Measurement, Calibration
    In search of alternate methods for conducting safer inspections, the reliability engineer investigated how infrared inspection windows (IR windows) might be utilised.
  • Temperature measurement within the plastics industry
    December 2018, Instrotech, Temperature Measurement
    Temperature is an important measurement parameter for many process techniques used in the plastics industry. Non-contact temperature measurement using an infrared sensor system is therefore an effective ...
  • Emerson’s compact new hygienic transmitters
    December 2018, Emerson Automation Solutions, Temperature Measurement
    Emerson has unveiled a new line of compact transmitters. Designed specifically for hygienic applications in the food and beverage industry, they will enable manufacturers to minimise downtime and lower ...
  • IRt/c setup with auto-tune ­temperature controllers
    November 2018, Temperature Controls, Temperature Measurement
    In many applications, heating elements are employed to heat a product in an oven, furnace, or with jets of hot air. Conventional control devices using contact thermocouples, measure and control the oven ...
  • SpotScan gives pyrometers ­scanning ability
    November 2018, R&C Instrumentation, Temperature Measurement
    Fluke Process Instruments recently introduced the SpotScan line scanning accessory for the Endurance, Marathon, and Modline ranges of IR non-contact temperature measurement sensors. The accessory features ...
  • Safety temperature measurement device for boilers
    October 2018, GHM Messtechnik SA, Temperature Measurement
    The Safety-TL4896, a SIL2 rated temperature measuring device from Martens, conforms to international boiler regulations and offers a unique front panel installation. Certified to DIN EN14597 and DIN EN61508, ...
  • Raytek pyrometer sensor now in 4-20 mA
    October 2018, R&C Instrumentation, Temperature Measurement
    About a decade ago, Raytek introduced the CM, a compact, integrated IR non-contact thermometer intended for quick and seamless replacement of J and K-type thermocouples. The CM, still an industry favourite, ...
  • Temperature sensor with drift monitoring
    October 2018, ifm Electronic RSA, Temperature Measurement
    The sensors of ifm electronics’ TAD series have two resistance elements with different characteristics (PT and NTC) that monitor each other permanently in the process. Drift is immediately detected and ...
  • Resistance thermometer for harsh conditions
    September 2018, Instrotech, Temperature Measurement
    Due to their extreme insensitivity to vibration, impact and shock load, Kobold’s TNK resistance thermometers are particularly suitable for monitoring the temperature of diesel engines. The extremely robust ...
  • ThermoView for industrial thermal imaging applications
    September 2018, R&C Instrumentation, Temperature Measurement
    Fluke Process Instruments recently announced the ThermoView TV40, a high-performance industrial thermal imager designed for the most challenging environmental conditions. Supported by intuitive and powerful ...
  • Temperature transmitter with new HART protocol
    September 2018, WIKA Instruments, Temperature Measurement
    The T32.xS temperature transmitter from WIKA is now also available in a version that communicates via the new HART 7 protocol. Another new function is an extended measuring point description (Long Tag). ...
  • Smart pyrometers for factory ­automation
    August 2018, R&C Instrumentation, Temperature Measurement
    Fluke Process Instruments has launched the Thermalert 4.0 spot pyrometer series for automatic non-contact temperature monitoring between -40 and 2250°C. The series currently comprises 13 models with varied ...

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