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Steam and air

Does steam and air mix? I have read that steam pushes the air out of the lines or radiators and have also read that steam and air mix so how would it push air out? I also heard Dan say in one of his videos that steam and air have different densities and, as such, they do not mix. So, I am just looking for clarification on that if possible. Thanks!


  • DanHolohan
    DanHolohan Member, Moderator, Administrator Posts: 16,553
    Steam is lighter than air, which is why it rises. It won't mix with the air in the pipes. It just shoves it ahead of itself. It also rides above the condensate in the horizontal pipes, which causes waves to form. When the waves crest at the tops of the pipes, the steam contained between any two crests will condense and cause the waves to bang into each other, which is the root of water hammer.
    Retired and loving it.