| 摘要 |
1,116,315. Detecting gases. NATIONAL RESEARCH DEVELOPMENT CORPORATION. April 7, 1967 [April 4, 1966], No. 14821/66. Heading G1B. Apparatus for the detection of gases comprises a gas detecting element 28 in a chamber 1 into which chamber, in one mode of operation gas can pass from the surrounding atmosphere through a diffuser 22 and nozzle means 11 are provided for permitting a second mode of operation in which a layer of gas, other than from the surrounding atmosphere is projected across the outer face of the diffuser so that only gas from the layer can pass through the diffuser and into the chamber. The detecting element 28 is connected to leads 26 mounted in an insulator 24 and comprises an electrically heatable catalytically acting element which varies its resistance with changes of temperature. A non-catalytic compensating element 29 is mounted in a second chamber 2. Below each diffuser 22 which is made of charcoal, a second diffuser 23 is mounted so that in the first mode of operation gas from the atmosphere passes through each diffuser 23 and forms a layer in the gap between the diffusers, from which layer gas passes through each diffuser 22 into the chambers 1 and 2. In the second mode of operation, gas. from a rubber bag is injected into the nozzle 11 through a duct 9 and into annular channels 8. Sintered bronze rings 16 are sealed in each channel by O-rings 17, 18 and provide a resistance to the flow of injected gas so that the pressure in the lower part of each recess 8 rises sufficiently to produce an evenly distributed radial flow of the gas to be sampled. In a modification, both elements 28, 29 are mounted on either side of a partition in a single chamber. |
