Keller pressure transmitters for hazardous gas and dust atmospheres

Keller AG introduces a complete range of pressure transmitters for use in hazardous areas.

Offering a measurement range of 0.2 bar – 1000 bar, Keller’s intrinsically safe transmitters can be used for measurements of all types in areas subject to explosion hazards in Group II (Gas), and as per the relevant ATEX Directive. Individual models from the product range are also approved for Group I (Mining) and Group II (Dust).

Key features of Keller Y-line pressure transmitters include very low temperature error with correspondingly high measure¬ment accuracy; and integrated temperature sensor and additional digital circuit that allow the range of envisaged opera¬ting temperatures to be divided into 120 sections with a width of 1.5 Kelvin. A mathe¬matical model is used during factory calibration to calculate individual compensation values for TK zero point and TK amplification for each of these sections, with the values stored in the transmitter. During operation, these values are fed into the analogue signal path according to the temperature, without reducing the 2 kHz signal processing dynamic. A relevant total error band for measure¬ment purposes of ±0.8 %FS can therefore be attained over the typical temperature range of -10°C to +80°C.

Keller’s X-line pressure transmitters (Series 30) additionally offer microcontroller-based electronic evaluation to ensure maxi¬mum accuracy. Each transmitter is gauged across the entire pressure and temperature range and the measurement data used to calculate a mathematical model that enables correction of all reproducible errors. Keller can therefore, guarantee high accuracy on the basis of an error bandwidth within the overall compensated pressure and temperature range.

Users of industrial transmitters may specify a choice of compensated temperature range at the time of purchase, depending upon the application; i.e., either -10…80 °C or 10…40 °C. Level transmitters are otherwise provided with a compensated range of 0…50°C. The calculated pressure value can be read via the interface, and is simul¬taneously processed as an analogue signal. At the digital output, the error band between 10…40 °C is a maximum of ±0.05% of the full range.

Keller’s intrinsically safe pressure transmitters are available in a varied selection of structural designs, electrical signals and mechanical connection formats allowing their use in an extensive range of applications.

The range includes models with internal seals as well as fully welded and flush front-sealed versions that measure pressure in absolute or barometric terms, or relative to ambient pressure. Various threads are available for the pressure connection, and different plugs and cables can be used for the electrical connection.

Users can also choose between typical industrial measurement signals with 3-wire technology (0…5V/ 0…10 V) or 2-wire technology (4…20 mA). An additional RS485 interface is available in addition to the analogue output in the Series 30 high-precision pressure transmitters and submersible sensors.

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