An Air-Enti Ainment Device for Preparing Precision Gas Mixtures

Abstract

Three low-cost venturi's built from readily available materials are described and evaluated to determine whether they can be used to prepare precision gas mixtures for the calibration of gas analysers. Using pure oxygen (0₂) and nitrogen as the priming gases the venturi's generated mixtures with an 0₂ concentration within the range 12-53% 0₂. Over a two-week period, the variability was found to be less than 0-25% 0₂. The mixtures produced were found to vary according to the density of the priming gas, but were virtually independent of the priming flow rate. We conclude that the venturi may offer a simple and inexpensive method of preparing precision gas mixtures suitable for the calibration of gas analysers.