GB1327839A - Molecular or combined oxygen detection apparatus and process - Google Patents

Abstract

1327839 Photo-electric measurement of oxygen content TRW INC 19 April 1971 [13 April 1970] 25808/71 Headings G1A and G1B [Also in Division C4] Apparatus for continuously detecting oxygen or the oxygen containing compounds SO 2 NO, NO 3 in a gas stream comprises a sensor with a solvent and a fluorescent material dissolved therein having a fluorescent lifetime # 1x10<SP>-9</SP> secs and capable of absorbing radiation of 2000 to 6500Š and emitting at 3000Š to 8000Š mounted as a film on a substrate; exciting source of 2000 to 6500Š, the fluorescence being quenchable by the oxygen or oxygen containing compounds and means to detect and record fluorescence changes. Fluorescent yield may be > 1%, (e.g. > 10%) the substrate film between 2 and 80 microns thick, equilibration response time a maximum at 0À1 seconds, the solvent of mineral oil, decalin, glycerol, tetrahydrofuran, benezene, hexane or solid greases, the fluorescent material pyrene, coronene, p-terphenyl or ovalene, fluorescent lifetimes being disclosed, the exciting source may be lasers, GaAs, Hg arcs, fluorescent tubes, W lamps and electro-luminescent devices and operation may be at “ to 10 atmos. and at room temperature. Fluorescent material concentrations are given and substrates may be mirrors, glass, silk mesh, nylon mesh, stainless steel, chromatographic paper, quartz Cu, cloth mesh, plastic film or wick material. Substrates may be opaque or transparent and may be reflectors such as white paper or shiny metals. Supported films include pyrene in mineral oil on a glass tube applied by dip coating spraying or swabbing; ovalene in mineral oil, a gel cast on a substrate e.g. pyrene in tetrahydrofuran with a thickening agent; pyrene in hexane absorbed on a sintered disc of silica gel, aluminia or molecular sieves. In Fig. 1, square glass tube 14 bears pyrene in mineral oil sensor film 15, with fitters 16, 17, u.v. source 20 emitting at 3000 to 4000Š and detector 21 with amplifier 22 and recorder 23 (e.g. a pen recorder or oscilloscope). Filters 16, 17 transmit at 3000 to 4000Š and 4200Š to 4800Š respectively. Calibration for maximum fluorescence is obtained by a nitrogen flow, Fig.2 (not shown), includes tube (24), sensor film (25) upper reflector (26), the bottom being transparent, Fig.7, includes phospor 30, Al foil 31, conductive flexible plate 32, plastic sealing jackets 35, 36, and liquid sensor 37 of ovalene in mineral oil. The detection process is insensitive to contaminants such as CO 2 , water vapour, Co and most compounds in surgical anaesthetics. Detection of oxygen in human and animal breathing is instanced to monitor many specific physiological parameters and many industrial and chemical detection applications are specified.