GB828151A - Gas sampling apparatus - Google Patents

Abstract

<PICT:0828151/III/1> Apparatus for taking an average sample of a flowing gas over a predetermined period comprises an inlet tube 18 having a branch 25 leading to one or more sampling tubes 26, a liquid reservoir 42 connected by a flexible tube 49 to the sampling tube or tubes, and mechanical means for lowering the reservoir 42 at a substantially constant rate. The gas supply flows through condensate trap 23 and then through vessel 28 to outlet 30. An additional liquid reservoir 43 is connected by flexible tube 50 to the bottom of the sampling tubes; before using the apparatus this reservoir is raised in order that liquid, e.g. mercury, may fill the sampling tubes; the reservoir 42 is also raised, excess liquid flowing through overflow 58 to vessel 40. The taps 36 are then opened to the gas source and the reservoir 42 slowly lowered by mechanical means, gas flowing into the sampling tubes 26 through capillary tube 25. The reservoir 42 is mounted on a runner which slides between vertical guide bars 63. Connected to the runner is a rack which engages a pinion driven through a gear-box by a clockwork motor. Operation of lever 82 varies the gear ratio and thus the period over which sampling occurs. When sampling is completed, taps 36, 41 are closed and the tubes 26 removed. The apparatus may be made of transparent material, e.g. glass, and may be mounted in a portable cabinet 1 together with a thermometer 9, pressure gauge 12, wander light 93, and a heater.