Aktieselskabet Bruel & Kjaer

Aktieselskabet Bruel & Kjar

Jorgen Christensen

Sten A Nexo

Ib E Jorgensen

A photoacoustic gas analyzer comprising a measuring chamber, a modulated light source, and at least one microphone in connection with the measuring chamber and measuring the changes of pressure caused by the absorption of the light in the chamber. The measuring chamber comprises an inner surface with a reflecting coating. The measuring signal is thereby proportional to the gas concentration and is not provided as the difference between two almost equal values. As a result it is possible to measure small gas concentrations provided the light intensity within the measuring chamber suffices.

Photoacoustic gas analyzer

Paramagnetic gas analyzer comprising an electromagnet with an almost closed ferromagnetic circuit and a gap, including a measuring chamber with inlet and outlet lines for the gas to be analyzed as well as a gas of known magnetic susceptibility where devices are provided which measure the differential gas pressures in the respective lines by supplying an AC current to the electromagnetic. According to the present invention it is shown, how the power consumption can be considerably reduced. This object is achieved by superimposing a DC magnetic field generated by means of a permanent magnet onto the AC magnetic field. The amplitude of the measuring result depends on the product of the AC field and the DC field. If the DC field is strong enough, the AC field and thus the supplied power can be reduced accordingly. The latter also facilitates the filtering off of predetermined, undesirable signals.

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Birkerød, Denmark

Jorgen Christensen