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Compressed Air Pressure Drop Across a Restriction

  1. Nov 29, 2008 #1
    I would like the formula that describes the reduction in pressure that results when a constant flow (cfm) of compressed air travels from a 3" diameter pipe through a bell reducer that provides a smooth transition to a 1.5" diameter pipe.

    Also, in the same piping configuration as described above, if the pressure drop is X psid acress the reducer, what will the pisd be if the cfm were doubled? What is the formula for this relationship as well?

    Is there a textbook that is available for non-engineers that describes the physics of compressed air in industrial compressed air systems?

    Thanks a million.
  2. jcsd
  3. Dec 2, 2008 #2


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    This is probably your best bet:

    http://www.flowoffluids.com/tp410.htm [Broken]

    Last edited by a moderator: May 3, 2017
  4. Dec 6, 2008 #3
    Thanks . . .
    . . . CS, for your help. The publication that you identified appears to be specifically for liquid fluids . . . I need compressed air information. Do both liguids and gases follow the same physics?
  5. Dec 6, 2008 #4


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    Hi Steve,
    The book stewartcs points out (Crane technical paper 410) is the bible of the industry. Process work throughout industry relies on it for fluid flow through piping systems. The paper specifically calls out where it is applicable and where not, so yes, it's applicable to compressed gas systems.
  6. Dec 6, 2008 #5


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    TP 410 does include gas flow as well as Q pointed out. It would be a great place for you to start.

  7. Dec 13, 2008 #6
    Thanks again. Crane TP 410 is where I will begin my search.

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