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Multi-Wavelength Technology

Williamson is the only company that offers two types of multi-wavelength pyrometers. The MW and MWx pyrometers are used to measure the temperature of non-greybody materials. These are materials for which the emissivity not only varies, but varies differently at different wavelengths.

Williamson’s multi-wavelength pyrometers use application specific algorithms to characterize infrared energy and emissivity to accurately calculate the temperature of these complex non-greybody materials. Algorithms have been developed and refined from extensive data collected from off-line simulations and on-line trials. These pyrometers also have a real-time measure of emissivity, confirming valid temperature measurement conditions and alerting you of invalid conditions that require troubleshooting.

Typical Non-Greybody Materials

  • Aluminum
  • Magnesium
  • Stainless Steel
  • Brass
  • Bronze
  • Copper
  • Zinc
MW Pyrometers provide consistent and accurate measurements with non-greybody materials under a wide range of operating conditions without any adjustments.  The MW pyrometers use application specific ESP Algorithms to accurately correct for emissivity variations due to:

  • Changes in alloy, surface texture, surface oxidation
  • Abnormal operating conditions such as a furnace leak, bad roll, or reheated coil (Annealing Line)

The most common applications involve aluminum, steel, and copper.  Each MW pyrometer can hold up to eight selectable algorithms so that the same sensor can be used for multiple applications.

The MWx pyrometers work differently than traditional MW technology which assumes that the surface conditions are relatively consistent.  The MWx sensors use Dynamic ESP Technology to automatically compensate for more significant variation in surface character and conditions without any adjustments.  The two applications which require the more advanced MWx technology are:

  • Aluminum hot rolling mills where the surface character of the aluminum varies dramatically by alloy and pass as it goes through the reversing mill.
  • High temperature (<900°F/480°C) aluminum billets where there is an elemental migration of aluminum to the outside billet surface that dramatically changes the emissivity of the billet surface.

Pro Series Products

The Pro Series is Williamson’s signature line of pyrometers which has been designed specifically for demanding industrial applications. It includes

Six different infrared technologies including single-wavelength, ratio, and multi-wavelength designs
A variety of wavelength options, temperature spans, and optical configurations
A choice of traditional style and more versatile fiber optic configurations
Advanced Ratio and Multi-Wavelength models include ESP Filtering to continuously measure intermittent targets or eliminate intermittent interferences
A wide range of options and accessories to simplify the alignment and installation of the pyrometers as well as provide protection from hostile operating conditions

Accurate Measurements Without Adjustments on Non-Greybody Materials

Some materials can be difficult or near impossible to measure with precision using single-wavelength or ratio pyrometers because their emissivity varies with wavelength. There are a variety of applications involving aluminum, steel, copper, zinc, and other non-greybody materials where multi-wavelength pyrometers are required to compensate for these complex emissivity characteristics.

Indicates the most appropriate pyrometer type depending on surface characteristics of the measured material.
Steel annealing lines which run high strength steels are one example where it is difficult to use traditional single-wavelength and ratio pyrometers to measure temperatures. With Williamson’s multi-wavelength pyrometer and the annealing line algorithm, it is possible to make consistent and accurate readings without any adjustments. This enables tighter control of temperatures to ensure that the desired mechanical properties are achieved.
Chart comparing Single-Wavelength, Ratio, and Multi-Wavelength pyrometers on steel annealing lines.

Popular Multi-Wavelength Applications

Steel & Zinc


Options & Accessories

Consult with one of Williamson’s Temperature Experts

We would love to discuss your temperature measurement application with you.

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