DIN EN ISO 6145-4-2008 气体分析.动态容量法制备校准气体混合物.第4部分:持续注射器注入法
Gas analysis - Preparation of calibration gas mixtures using dynamic volumetric methods - Part 4: Continuous syringe injection method (ISO 6145-4:2004); English version of DIN EN ISO 6145-4:2008-11
This part of ISO 6145 specifies a method for continuous production of calibration gas mixtures containing two
or more components, from pure gases or other gas mixtures by continuous injection of the calibration
component(s) into a complementary gas stream by means of a syringe.
If pre-mixed gases are used instead of pure gases (see Annex A), much lower volume fractions can be
obtained. The volume flow rates, from which the volume fractions are determined, can be calculated from the
individual flow rates and can be independently measured by a suitable method given in ISO 6145-1.
The merits of the method are that a substantial quantity of the gas mixture can be prepared on a continuous
basis and that multi-component mixtures can be prepared almost as readily as binary mixtures if the
appropriate number of syringes is utilized, or if the syringe already contains a multi-component mixture of
known composition. This method also provides a convenient means for increasing the volume fraction of the
calibration component in the mixture in small steps. II is therefore a useful method for evaluation of other
characteristics of gas analysers, such as minimum detection limit and dead zone, as well as accuracy. The
relative expanded uncertainty in the volume fraction obtainable for a binary mixture (at a coverage factor of 2) is
5 % and the range of applicability is 10-5 to 10 -2.