The Sirius line of Pyrometers was developed to meet the growing demand for small and easy-to-install sensors with first-class optical and electronic characteristics. Sirius-Pyrometers operate at the near end of the infrared spectrum and are therefore an excellent choice for measurement of ferrous and non-ferrous metals above 250°C because the emissivity of un-oxidized metal surfaces is higher at shorter wavelengths. Other major advantages are the lower sensitivity for changes in emissivity at shorter wavelengths.
The units are exceptionally robust due to the fact that the measuring process is performed without mechanically moving parts and because the lens, detector and electronics are housed in a stainless steel cabinet. By utilizing the digital signal process, the Sirius line exceeds standard analog Pyrometers as far as precision and repeatability are concerned.
The infrared energy radiated by the target is centered directly on the detector by factory provided
focused lenses. Lenses are made of BK7, an optical glass which is highly transparent in the spectral region ofSirius SS and SI. If additional windows are necessary, they must offer similar optical characteristics.
The detector is sensitive to infrared radiation in an area called cone of vision. For the spot size diameter Ø of it at shortest, medium and widest distances, if focused, pls. see Chart 2. The cone of vision diameter in front of the lens is about 14 mm. This area has to be kept free from any intervening objects. The spot size diameter for distances not given in the chart can be calculated by interpolation.
The optical alignment of the Pyrometers on the measured object is facilitated by the precise
laser marking which indicates the centre of the measured spot. The optical axis is aligned with the mechanical
axis of the sensor housing. The laser can be switched on directly at the back of the housing or by an externally
Temperature Output Signal:
Sirius Pyrometers offer analog and digital output signals for indication, recording, archiving and controlling of measured process temperatures. The isolated analog output is selectable from 0 to 4 to 20 mA. Zero- and full-scale temperatures are adjustable to cover any portion of the instrument’s available temperature span to a minimum of 51°C. There is a choice of 23 digital communication interfaces: RS 232 or RS 485 max. 57.6 kBd.
For measuring and holding of the highest instantaneous temperature value a peak picker (maximum value storage) is installed to compensate interruptions or attenuations in radiation caused by bursts of steam, smoke or dust. It can be either reset automatically, by an external contact closure or periodically, by user preset clear time. In this last case the highest temperature will be held in a dual storage and will be reset in only one of the two storages, after preset clear time to avoid a decrease of the temperature output, should a short cold period appear just at the reset moment. The exposition time is the length of time it takes for the output signal to reach 90% of a step change in measured temperature. It can be used to filter out rapid variations in temperature and achieve a “more quiet” signal for control or display purposes.