Abstract: The present invention is an apparatus for detecting iron based particulate matter in air/gas streams. The sensor 10 includes a flow through sensor body 11 having an interior surface. A high power magnet 12 for use in attracting airborne iron particulate matter is formed as part 13 of the interior surface of the sensor body. A high contrast photoelectric sensor 14 coupled to a fiber optic bundle 15 is used for detecting changes in the contrast of the magnetic surface.

Abstract: Apparatus for curtain coating a web or article includes a coating hopper, a support roller, guide rollers for leading the web to and from the support roller and an enclosure. Air which has been conditioned in respect of temperature, humidity and cleanliness is introduced into an upper region of the enclosure. Air flow controlling means are provided below the region into which the conditioned air is introduced. The flow controlling means serve to control the flow of air downwards so that it is uniform across a horizontal plane within the enclosure and has a speed of about 10 feed per minute in the region of the coating liquids in the curtain, that being a speed which will not cause disturbing effects on the liquids in the curtain. The enclosure prevents random air currents of uncontrolled velocity, temperature and cleanliness impinging on the liquids in the curtain and on the slide, which might otherwise adversely affect the product coating.