GB779824A - Apparatus for the continuous automatic measurement of the quantity of a certain gas in a gas mixture - Google Patents

Abstract

<PICT:0779824/III/1> <PICT:0779824/III/2> An apparatus for measuring the quantity of a gas in a mixture e.g. of carbon dioxide in combustion gases comprises an admission chamber (3) in open communication with the atmosphere, a device (7) capable of varying the volume of the gas by reaction of or physical change in one of its components, a gas pump (12) by means of which the gas can be drawn through said admission chamber and said device (7) a valve (11) in the suction pipe of said pump and flow meters (8 and 10) respectively connected between the admission chamber and said device and said device and the pump. The figures in brackets refer to the illustrated embodiment in which the flow meters comprise pressure gauges, the first of which (8) is preceded by an orifice plate 5 and the second of which (10) is a differential pressure gauge which is connected across an orifice plate 9. In operation, the valve 2 in the supply tube 1 is first turned off and air drawn through the apparatus from the surrounding atmosphere through tube 4 and the reading ha of pressure gauge 8 is noted (zero); the reading Ha on flow meter 10 is also noted. Valve 2 is then opened and by means of valve 11 sufficient gas is caused to pass through the apparatus as will provide the same value Ha on the pressure gauge 10. The new reading of gauge 8 is then a direct measure of the gas component affected. During the taking of this reading valve 2 is opened sufficiently widely that some of the gas passes out of the admission chamber 3 into the atmosphere. In Fig. 2 is shown a suitable device 7: an absorbent liquid such as potassium hydroxide solution is contained in a vessel 19 inside which an open ended cylinder 18 is provided. This surrounds, but is not in contact with a helical strip 17 attached to a central tube 6 corresponding to tube 6 on Fig. 1. An orifice 21 provides for bubbles of the gas to be tested passing into the absorbent and these then follow the helical strip and pass upwardly through the absorbent finally passing out of the apparatus through the orifice plate 9 as described in relation to Fig. 1. A solid absorbent may be used in some cases e.g. phosphorus may be used to absorb oxygen. The device 7 could also be a combustion chamber with electric heating for use in determining the quantity of hydrocarbons in the gas mixture.