ISO 6145-7:2009 specifies a method for continuous production of calibration gas mixtures, containing two or more components, from pure gases or other gas mixtures by use of commercially available thermal mass-flow controllers.
If this method is employed for the preparation of calibration gas mixtures, the optimum performance is as follows: the relative expanded uncertainty of measurement, U, obtained by multiplying the combined standard uncertainty by a coverage factor k = 2, is not greater than 2 %.
If pre-mixed gases are used instead of pure gases, mole fractions below 10-6 can be obtained. The measurement of mass flow is not absolute and the flow controller requires independent calibration.
The merits of the method are that a large quantity of the gas mixture can be prepared on a continuous basis and that multicomponent mixtures can be prepared as readily as binary mixtures if the appropriate number of thermal mass-flow controllers is utilized.
Status: WithdrawnPublication date: 2009-04
Edition: 2Number of pages: 15
Technical Committee: ISO/TC 158 Analysis of gases
- ICS :
- 71.040.40 Chemical analysis
ISO 6145-7:2009Stage: 95.99
Got a question?
Check out our FAQs
Monday to Friday - 09:00-12:00, 14:00-17:00 (UTC+1)
Keep up to date with ISO
Sign up to our newsletter for the latest news, views and product information.