GB790364A - Improvements in and relating to the delivering of measured quantities of gases or vapours - Google Patents

Abstract

<PICT:0790364/III/1> <PICT:0790364/III/2> <PICT:0790364/III/3> Apparatus for delivering automatically a measured volume of gas or vapour comprises two valves 1, 11, Fig. 1, each having a metal body and a rotatable metal plug, the plugs 3, 31 being connected by a spindle 31 which may be rotated by arm 6. Four tubes 7 ... 10 and 71 ... 101 radiate from the body of each valve and the valve plugs are provided with transverse ducts 14, 141 and V-shaped ducts 15, 151 which may be arranged as in Fig. 3 or as in Fig. 4. In the position of Fig. 4, the gas to be measured flows in at 10, through ducts 14, 9, X, 91, 141, and to atmosphere at 101; meanwhile inert gas, e.g. nitrogen, enters at 8 and passes through ducts 15, 7, Y, 71, 151 to outlet 81 leading to the apparatus to be supplied with gas. On movement of the valves to the position of Fig. 3, the inert gas sweeps the gas sample from the tubes 9, X, 91 to the outlet 81. As shown in Fig. 1, springs 22, 221 act on projections 20, 201 of the valve plugs to press the plugs into the bodies. Pegs 26, 261 co-operate with peripheral slots in discs 21, 211 to provide stop positions for the valves. The apparatus may be operated automatically by means of a motor and process controller, an electrically-controlled valve for compressed gas, a spring-loaded diaphragm actuated by the compressed gas, and means operated by the diaphragm for moving the arm 6 of the apparatus. The gas samples may be delivered to apparatus for gas analysis or vapour phase chromatography. A jacketed chromatographic column may contain silica gel, activated carbon or charcoal, or liquid paraffin supported on diatomaceous earth. The composition of the gas issuing from the column is measured by a hot wire katharometer or a thermistor, and a recording potentiometer.