[Methods of gas mixture preparation]

State methods for preparation of gas mixtures have many disadvantages. Losses of components due to adsorbtion on the container surface (glass of plastic) are the main problem. Flow--dilution dynamic systems are much more convenient, giving practically unlimited quantities of mixtures of chemical substances with air at fixed concentration. Dynamic methods enable rapid change in concentration of generated mixture and surface adsorbtion does not exist. To produce at stable rate the substance to be diluted with air, microdiffusion, motor driven syringes (or peristaltic pumps) saturated vapours, permeation tubes and pressure cylinders may be employed. Our experience showed that pressure cylinders are the best for preparation of mixtures of gases (i.e. vinyl chloride) with air and peristaltic pumps are the best as the source of vapours for further dilution. The latter method may be employed as well for mixtures of several compounds (i.e. acetic acid esters) with air.