Analysing gas/air mixtures for seal monitoring system - using intensity variations caused by infrared or ultraviolet absorption

摘要

The mixture to be analysed is input to an operating chamber where it is subjected to infrared or ultraviolet radiation which becomes modulated by the absorption band of the gas. The contents are evaluated from the intensity variation. The gas-air mixture is fed into the chamber until the pressure exceeds atmospheric. The pressure is held constant during three or more radiation cycles. The effect of the radiation commences immediately the pressure exceeds the atmospheric pressure. Before the mixture is fed in, a gas which does not absorb the infrared or ultraviolet radiation is passed through the chamber which is then evacuated to a pressure below atmospheric so as to increase the gas conc. in the mixture. The method for analysing gas-air mixtures is applicable to monitoring the sealing of many different objects in widely different areas of application, e.g. in the aircraft and motor vehicle industries.