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Martin, Engineer
Category: General
Satisfied Customers: 4776
Experience:  i'm 41 and i never stopped studying and experimenting
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Which gas is heaviest and which is lightest

Resolved Question:

Of Nitrogen Gas, Methane Gas (from wastewater treatment anorobic digesters) and atmospheric oxygen, which is lightest to heaviest. I need to purge a sealed vessel of Methane digester gas using Nitrogen, open the vessel, then after servicing seal it and purge the atmospheric oxygen from within the tank with Nitrogen gas, to eliminate the potential of gas and air together creating an explosive mix. The Methane digester gas is used as a fuel, similar to pipeline quality natural gas, for an internal combustion engine driving a generator. The Methane is vented out the top or bottom, as is the oxygen, purged with the Nitrogen gas. I would like to know which direction to properly purge the gases. Thanks.
Submitted: 7 years ago.
Category: General
Expert:  Martin replied 7 years ago.
Methane is the lightest, then Nitrogen, then Oxygen.

So you should purge first with nitrogen from the bottom, evacuating methane from the top, then put nitrogen from the top for evacuating oxygen at the bottom.
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