GB1347389A - Device for detecting hydrocarbon components in a gaseous mixture - Google Patents

Abstract

1347389 Detecting hydrocarbons UNION CARBIDE CANADA Ltd 26 May 1971 [4 June 1970] 17119/71 Heading G1B [Also in Division H1] A device for detecting a hydrocarbon component in a gaseous mixture includes a two-layer strip 2 rigidly secured to a support 3 at one end but freely movable at the other end, each of the layers being of a different flexible material, a first one 7 of the layers being a hydrocarbon polymer which absorbs the component, the other components of the mixture being insoluble in both materials, the hydrocarbon component, if present, swelling the layer 7 and thus deflecting the strip, and co-operable with the free end of the strip to sense the deflection e. g. a mercury switch 4 coupled to alarm 6, a contact switch, a mirror and scale, or a calibrated scale. The first layer is preferably a polyolefin or polydiene and the second layer cellulose, aluminium foil or copper foil. The use of an uncross-linked hydrocarbon polymer for the first layer and the cross-linked hydrocarbon polymer for the second layer compensates for differential thermal expansion between the layers. If the two materials each absorb a different hydrocarbon component, the net deflection of the strip is a measure of their relative concentrations in the mixture. The strip 2 may be a spiral as in Fig.1, straight as in Fig. 2 (not shown), or semicircular and placed across and in a pipe as in Fig.3 (not shown).