| 摘要 |
<PICT:0487281/III/1> <PICT:0487281/III/2> In a device for detecting the concentration of combustible gases, e.g. methane in mine atmospheres, a sample of the gas is primed by the addition thereto of a vaporized supplementary fuel, whose vapour concentration is automatically regulated preferably to a constant value, and is then subjected to ignition, an eventual explosion being utilized to operate an indicating device. In the illustrated apparatus, the gas is forced by a diaphragm pump 16 into a space 4 in which a candle 2 of naphthalene mixed with b -naphthol is pressed down by a spring 3. The candle is heated by means (not shown) which may be automatically regulated by a device 15 responsive to variations of atmospheric pressure, so as to maintain a constant vapour pressure of naphthalene. The primed gas passes to an explosion chamber 5 fitted with a sparking plug 7 which is periodically actuated through a synchronous motor. The chamber has a diaphragm pressure gauge 8 which on the occurrence of explosion makes a contact 9 closing the circuit of the indicating device. |
