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

Scope

This document specifies a method for dynamically preparing calibration gas mixtures using a critical flow orifice system. The calibration gas mixtures shall include at least two gases, either pure gases or pre-mixed gases (one of which is usually a supplementary gas).
The method specified in this document is primarily applicable to the preparation of gas mixtures that do not react with the materials of the gas pipelines in the critical flow orifice system or auxiliary equipment. By using an appropriate number of critical flow orifices, multi-component gas mixtures can be prepared.
By selecting an appropriate combination of critical flow orifices, the dilution ratio can reach 1×104.
Although the method specified in this document is typically used to prepare gas mixtures under atmospheric pressure conditions, it can also be used to prepare calibration gas mixtures under pressures exceeding atmospheric pressure. When using the method specified in this document, the upstream gas pressure must be at least twice as high as the downstream gas pressure.
The applicable flow range of this document is 1 mL/min to 10 L/min.

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