Say I have a proposed setup as per the following illustration (Fig 1.). A pipe carries an unknown mixture of compressible gas from left to right under a vacuum (black arrows). By introducing a constriction in the flow a pressure difference is obtained before the converging section. The higher pressure before the constriction forces the gas in the main pipe to flow through the sample collection tube into a sample collection chamber (blue arrow). A one-way valve for ambient air intake resides in the sample collection chamber. The sample collection chamber is connected on the other end to the venturi constriction with a larger diameter tube, creating a vacuum (red arrows) in the collection chamber drawing in ambient air through the one-way valve.

The sample in the collection chamber must equal 1% of the live pipe's gas composition, mixed in the ratio of 1:99 with ambient air. My layman's hypothesis is that the gas sample tube (or its nozzle) leading to the sample collection chamber must be 1 unit, the ambient air intake 99 units and the collection chamber outlet 100 units in a cross-sectional area to make it work. Dilution of the process gas by returning the air-enriched sample back into recirculation is not an issue from the process perspective.

Would there be a better/more straightforward way to accomplish what I'm trying to achieve? Thanks in advance for your valuable input.

Fig 1.

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