ISO 6145-2:2014
Gas analysis - Preparation of calibration gas mixtures using dynamic methods - Part 2: Piston pumps

Standard No.

ISO 6145-2:2014

Release Date

2014

Published By

International Organization for Standardization (ISO)

Latest

ISO 6145-2:2014

Scope

the preparation of calibration gas mixtures. This part of ISO 6145 describes a method and preparation system using piston pumps. The mixture composition and its associated uncertainty are based on calibration of the piston pumps by dimensional measurements. The calibration gas mixtures prepared using this method consist of two or more components, prepared from pure gases or other gas mixtures using gas-mixing pumps. Such gas-mixing pumps contain at least two piston pumps, each driven with a defined ratio of strokes, and appropriate accessories for gas feeding and mixture homogenization. This part of ISO 6145 is applicable only to mixtures of gaseous or totally vaporized components including corrosive gases, as long as these components neither react with each other nor with the wetted surfaces of the mixing pump. The use of gas mixtures as parent gases is covered as well. Multi-component gas mixtures and multi-step dilution procedures are included in this International Standard as they are considered to be special cases of the preparation of two-component mixtures. This part of ISO 6145 describes a method of preparing calibration gas mixtures whose composition is expressed in volume fractions. The necessary equations and associated uncertainty evaluation to express the gas composition in amount–of–substance fractions are given in Annex A. With this method, provided that sufficient quality assurance and control measures are taken, calibration gas mixtures can be prepared with a relative expanded uncertainty of 0,5 % (coverage factor k = 2) in the volume fraction. Numerical examples showing that under specified conditions smaller uncertainties are attainable are given in Annexes B through D. Using this method, dilution ratios of 1:10000 can be achieved in discrete increments. Lower fractions (down to 1 × 10−8) can be achieved by multi-stage dilution or by the use of gas mixtures as input gases. Final mixture flow rates of 5 l/h to 500 l/h can be realized depending on the equipment used.

ISO 6145-2:2014 Referenced Document

• ISO 14912:2003 Gas analysis - Conversion of gas mixture composition data
• ISO 6142:2001 Gas analysis - Preparation of calibration gas mixtures - Gravimetric method
• ISO 6143:2001 Gas analysis - Comparison methods for determining and checking the composition of calibration gas mixtures
• ISO 7504:2001 Gas analysis - Vocabulary
• ISO/IEC Guide 98-3:2008 Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in measurement (GUM:1995)
• ISO/IEC Guide 99:2007 International vocabulary of metrology - Basic and general concepts and associated terms (VIM)

ISO 6145-2:2014 history

• 2014 ISO 6145-2:2014 Gas analysis - Preparation of calibration gas mixtures using dynamic methods - Part 2: Piston pumps
• 2001 ISO 6145-2:2001 Gas analysis - Preparation of calibration gas mixtures using dynamic volumetric methods - Part 2: Volumetric pumps