| 摘要 |
1,242,482. Gas analysis. BECKMAN INSTRUMENTS Inc. Sept.8, 1969 [Sept.18, 1968; March 27, 1969], No.44321/69. Heading G1B. Apparatus for the analysis of the exhaust gas of internal combustion engines comprises a sampling probe 12 for insertion into a vehicle exhaust pipe 14, the probe leading to a condenser and filter assembly 15 with an inlet 40 passing into an inner chamber 32, the gases being cooled therein by circulation of air from a hose 80 in a surrounding outer chamber 36 so as to condense water vapour in the exhaust gas, which leaves by passage through a filter 44 leading to an outlet 42, the temperature of the gas at this stage being substantially that of the ambient atmosphere, and a conduit 18 leading to an analyzer 16 with a heater 54 located in the conduit 18 to raise the gas temperature above that of the ambient atmosphere whereby condensation of water vapour remaining in the exhaust gas in the analyser is obviated. Gases are drawn through the apparatus by means of a jet pump 20 comprising two concentric tubes 60, 64, the outer of which is connected to the outlet 62 of the analyzer and the inner of which is fed with air from a source of compressed air 90. The source 90 also supplies the cooling air for the chamber 36 of the assembly 15 by way of the hose 80. The probe 12 is preferably a corrugated tube of a length sufficient to cool the exhaust gases to near ambient temperature. It is preferably disposed in a loop from the exhaust pipe 14 to the assembly 15 so as to form an initial water trap for condensed water vapour. Water condensed on the walls of the chamber 32 in the device 15 may be run out through a valve 50 when desired. The analyzer 16 is described as an infrared analyzer with a test cell 26 an infrared source 22 and a thermistor bolometer detector 24. In some cases the heater 54 may be dispensed with if the conduit 18 is disposed in a housing together with the infrared source 22 so that the gases will be heated by this source. A valve 56 is also included in the conduit 18 whereby a calibration gas may be fed to the analyzer 16 from a source 58. |
