RO
SR EN ISO 6145-7:2019
Gas analysis - Preparation of calibration gas mixtures using dynamic methods - Part 7: Thermal mass-flow controllers (ISO 6145-7:2018)
ISO 6145 is a series of documents dealing with various dynamic methods used for the preparation of calibration gas mixtures. This document specifies a method for continuous preparation of calibration gas mixtures, from nominally pure gases or gas mixtures by use of thermal mass-flow controllers. The method is applicable to preparation of mixtures of non-reacting species, i.e. those which do not react with any material of construction of the flow path in the thermal mass-flow controller or the ancillary equipment. If this method is employed for preparation of calibration gas mixtures the optimum performance is as follows: the relative expanded measurement uncertainty U, obtained by multiplying the 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 calibration gas mixture can be prepared on a continuous ba
Status :
Valid
Approval date : 5/31/2019
Number of pages : 22
ICS : 71.040.40 Chemical analysis
Technical Committee : 357 - Natural gas
- Replaces SR EN ISO 6145-7:2011
- Normative reference SR EN ISO 6143:2007
- Normative reference SR EN ISO 6145-1:2020
- Normative reference SR ISO 7504:2016
- Normative reference SR ISO 12963:2018
- Normative reference SR ISO 19229:2016