Intrinsically safe photoelectric sensors for explosive atmospheres

Citation

(1999), "Intrinsically safe photoelectric sensors for explosive atmospheres", Pigment & Resin Technology, Vol. 28 No. 2. https://doi.org/10.1108/prt.1999.12928bad.018

Intrinsically safe photoelectric sensors for explosive atmospheres

Intrinsically safe photoelectric sensors for explosive atmospheres

Keywords Leuze Mayser, Photoelectric sensors, Sensors

Leuze Mayser has considerably extended the application possibilities of its photoelectric sensors with the launch of intrinsically safe models classified according to class EEx ia IIC T6 and reported to be suitable for use in any potentially explosive atmosphere of zones 0, 1 and 2.

The new Series 92 intrinsically safe models are available in three basic design formats to satisfy most requirements in terms of functionality and span. These are thru'beam sensors with a range of 12m, polarized retroreflective models which have a span of 5m and diffuse reflection scanners with adjustable background suppression and a maximum scanning depth of 300mm.

Leuze has designed all three configurations to operate with a switching frequency of 60Hz, a standard stipulated for intrinsically safe sensors, permitting them to reliably detect even relatively fast moving or small objects. A feature of the sensors is the special finish to the resilient metal housing that prevents build-up of static. The dimensions of the new intrinsically safe photoelectric sensors are 80 × 42 × 20mm and they are supplied as standard with a circular M1 connector that simplifies electrical connection and the switching output corresponds to DIN 19234 (NAMUR). When required, Leuze will supply isolating switching amplifiers in different versions.

Typical applications for the sensors include chemical, petro-chemical or pharmaceutical installations, automatic painting lines, perspex production plants or filling plants for spray cans using inflammable propellant gas as well as paper processing, printing or woodworking machinery. The processes involved in these industries can produce gases or vapours that form potentially explosive mixtures in conjunction with the oxygen in the air. The probability of the occurrence of this type of potentially explosive atmosphere determines the classification according to zones. Zone 0 is used for atmospheres which are highly explosive practically all the time, in Zone 1 explosive conditions frequently exist and in Zone 2 they are the exception rather than the rule.

According to Leuze Mayser the explosion-proofed photoelectric sensors are seen as a significant addition to its sensor family as they comply with the stringent guidelines laid down by the German Chemical Industry Employers' Liability Insurance Association, and also hold a conformance certificate from the DMT-BVS (BVS 97.D.2071).

Details are available from Leuze Mayser Electronic Ltd. Tel: 01480 408500; Fax: 01480 403808.