| 摘要 |
<p>The paper undergoes a colour change (from red-brown to white) depending to the concn., gas throughput and time, and the degree of colour change is a measure of the conc. The traces of Cl2 in the gas are converted to HCl in a definite ratio. The gas pref. is heated (to 900 degrees C) and then cooled to room temp. before entering the analyser, whilst interfering components, e.g. HCl, HBr and HI are absorbed bedore heating. Max. colour change is obtd. in 30 min. with 50 1/h air contg. 10 ppm Cl2. If the heating and cooling stages are used, this is reduced to 3 min. The appts. has a measuring chamber through which a strip of indicator paper passes. Light emitted by a source through an optical filter (passing 380-510 nm) is reflected diffusely by the indicator paper and measured with a photocell. There pref. is also a gas sampler, very fine filter absorption tower, reaction furnace and gas cooler before the analyser.</p> |
