GB/T 5275.6-2023Gas analysis - Preparation of calibration gas mixtures using dynamic methods - Part 6: Critical flow orifices (English PDF)

1 Scope

This document specifies a method for the dynamic preparation of calibration gas mixtures using a critical flow orifice system: Calibration mixed gas consists of at least

Two gases (one of which is usually make-up gas) either pure or premixed:

The method specified in this document is mainly applicable to the preparation of gas pipeline materials that do not react with critical flow orifice systems or auxiliary equipment:

mixed composition: When an appropriate number of critical flow orifices are used, multi-component gas mixtures can be prepared:

The dilution ratio can reach 1×104 by choosing a suitable critical flow orifice combination:

Although the methods specified in this document are generally applied to the preparation of gas mixtures under atmospheric pressure conditions, the methods specified in this document can also be used

Preparation of calibration gas mixture at a pressure exceeding atmospheric pressure: Using the method specified in this document, the upstream gas pressure needs to be at least higher than the downstream gas pressure:

twice as high:

The applicable flow range of this document is 1mL/min~10L/min:

2 Normative references

The contents of the following documents constitute the essential provisions of this document through normative references in the text: Among them, dated references

For documents, only the version corresponding to the date is applicable to this document; for undated reference documents, the latest version (including all amendments) is applicable to this document:

ISO 6143 Comparison method for the determination and verification of gas analysis calibration gas mixture composition (Gasanalysis-Comparison

Note: GB/T 10628-2008 Determination and verification comparison method of gas analysis calibration mixture gas composition (ISO 6143:2001, IDT)

ISO 7504 Gas Analysis Vocabulary (Gasanalysis-Vocabulary)

Note: GB/T 14850-2020 Gas Analysis Vocabulary (ISO 7504:2015, IDT)

Venturinozzles)

Note: GB/T 21188-2007 measures gas flow with a critical flow Venturi nozzle (ISO 9300:2005, IDT)

ISO 12963 Gas analysis, comparative method for determination of gas mixture composition based on one-point and two-point calibration (Gasanalysis- pointcalibration)

ISO 16664 Guidelines for the use of pure and mixed gases for gas analysis calibration (Gasanalysis-Handlingofcalibra-

Note: GB/T 37180-2018 Guidelines for the use of pure gas and mixed gas for gas analysis calibration (ISO 16664:2017, IDT)

3 Terms and Definitions

The terms and definitions defined in ISO 9300, ISO 7504 and the following apply to this document:

3:1 criticalflow orifice criticalfloworifice

Orifice whose geometry and conditions of use allow the throat flow to reach the critical flow (3:12)

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