Apparatus for the determination of nitrogen oxides in air

Claim 1

In an apparatus for simultaneously determining the amounts of nitrogen monoxide and nitrogen dioxide in air by means of an apparatus comprising an ozonizer suitable for supplying a continuous stream of ozone, a reaction chamber positioned to receive ozone from said ozonizer and air containing nitrogen oxide or air free of nitrogen oxide and containing a photomultiplier for measuring the luminescence emission of the reaction between nitrogen monoxide and ozone, a conduit connecting said ozonizer to said reaction chamber for transferring said ozone to said reaction chamber, a gas conduit opening into said reaction chamber containing a valve suitable for admitting air free of nitrogen oxide or air to be analyzed through said conduit opening into said reaction chamber, a reducer connected to said valve for reducing nitrogen dioxide in the air to be analyzed to nitrogen monoxide and a valved by-passing conduit for by-passing the reducer the improvement wherein said reducer comprises a container having an inlet and an outlet and is filled with a granular mixture of ferrous sulphate and an alkali metal acid sulphate in a molar ratio of from 3:1 to 1:1.