FLAME-IONISATION DETECTOR Russian patent published in 2014 - IPC G01N30/00 

FIELD: instrumentation.

SUBSTANCE: flame ionisation detector comprises a stainless steel housing made in the form of a cup with a lid with the channels located in it for supplying air, hydrogen, gaseous sample, and the channel located in the lid for outlet of the combustion products, and the flame ignition element. In the lower part of the housing coaxially and in alignment with the channel for supplying the gaseous sample the metal burner electrically connected with the housing is fixed. A channel for supplying the gaseous sample is connected pneumatically with the burner and the channel for supplying hydrogen, at the output of which in the direct proximity of the burner the pneumatic resistance is mounted, which area of passage is less than the area of passage of the burner. In the housing of the detector the collector electrode is located coaxially made in the form of the metal sleeve and simultaneously acting as a polarising electrode, which is connected to the input of an electrometer amplifier through the central cable of the triaxial communication link. The collector electrode is placed in the electromagnetic screen insulated from it and the detector housing with the electrically insulating sleeves, connected via the electromagnetic screen of the triaxial communication link with the electromagnetic screen of the amplifier, electrically insulated from the amplifier housing. At the output of the electrometer amplifier there is an analogue-digital converter with the galvanic isolation. The polarisation voltage source with one of its "poles" is connected to the common wire of the electrometer amplifier, and the other "pole" through electrically insulated from the housing screened wire is connected only with the housing of the detector. In the electromagnetic screen of the collector coaxially with the channel for supplying air, located in the side wall of the cylindrical housing of the detector, an opening is made, which diameter is larger than the inner diameter of the channel for supplying air.

EFFECT: improving the metrological characteristics of the detector due to reducing the level of fluctuation noise and expansion of linear dynamic range of the detector changes.

2 cl, 1 dwg