New infrared sensor offers improved performance in harsh industrial environments

Phil Black - PII Editor 13/01/2009

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Ircon(r), the worldwide leader in infrared (IR) noncontact temperature measurement, has introduced an enhanced version of its Modline 5R Infrared Thermometer with advanced signal detection and attenuation alarming capabilities. The new Modline 5 Series 5R Ratio Sensors are designed for non-contact infrared temperature measurement applications involving harsh industrial environments.

With most two-color infrared thermometers, an invalid indication is reached when the reduction in signal from the target is greater than 95 percent. When the signal reduction is too great, an invalid condition occurs. This
variation can be caused by emission characteristics of the target or the target being too small to completely resolve, as well as obstructions in the sight path (i.e., certain types of smoke). When an invalid condition occurs,
an alarm output is provided to indicate the signal variation is too great between the two detectors. While this type of detection method is suitable for many applications, there are some instances where the user wants to
adjust the sensitivity level of attenuation.

The Ircon Modline 5 Series 5R Ratio Sensors utilize a dual detector assembly that measures temperature by comparing infrared radiation levels in two wavelength bands (0.85 to 1.05 microns and 1.0 to 1.1 microns). Temperature readings are based on the ratio of the two signals in these bands. Because the sensors measure the ratio of radiation intensities at two wavelengths rather than the absolute intensity of radiation at a single wavelength, they are almost immune to error caused by loss of signal. Small targets that do not fill the field of view, and partial obstructions from bursts of steam, dust and solid objects in their sight path, can be tolerated.

The Modline 5 Series also provides a new attenuation alarming capability based on the proprietary Raytek signal attenuation measurement algorithm (U.S. patent No. 5,815,410) allowing users to adjust the alarm sensitivity
level. By measuring the attenuation, the sensor can provide a notification
alarm when attenuation levels exceed a user-defined setpoint limit.

The Modline 5 attenuation adjustment alarming feature operates independent from the optional dirty window detector, which will monitor the sensor window for contamination. It enables users to monitor any kind of signal
attenuation caused by dirty viewports or other external windows. Attenuation alarm settings are configurable from 5 to 95 percent, from either the back panel of the sensing head or from the Ircon Modview program. When an alarm condition is detected, relay outputs provide notification to external process control instrumentation.

When the attenuation adjustment alarming feature is enabled, the user can monitor attenuation levels in a graphical format in the Modview program providing a historical view of the levels. In addition, attenuation levels
are available through the Modline 5 RS-485 output fed into an external device.

Contacts:
U.S. & Canada: Arlene Lucas Starrh arlene@raytek.com
U.K.: Jutta Schwelm jschwelm@raytek.de
Latin America & Asia: Arlene Lucas Starrharlene@raytek.com