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Fan total pressure enough or not?

  1. Aug 23, 2014 #1
    Dear all

    I'm designing an exhaust system for a wood working facility. Please correct me if I'm wrong as I'm new to this industry:

    The system needs about 4.8 m^3/s airflow (with main duct velocity of 20m/s and branch velocity of 23 m/s). The total pressure drop due to the ducts and fittings up to fan inlet is about 1500 Pa. For some reasons, the air cleaning device (bag house) has to be installed on the outlet side of the fan . I already have a fan which can handle this flow rate but the total pressure of the fan at this flow rate is about 1800 Pa according to its fan curve. I obtained the fan curve myself based on the AMCA 210-07 standard and pitot traverse method. I believe if I add the pressure loss due to the bag filter, the fan is not suitable. If I assume the bag filter has the pressure drop of about 1500 Pa after the dust cake has been created, I need a fan which can handle total pressure loss of 3000 Pa @ 4.8 m^3/s which means the fan I have is not suitable. (correct me if I'm wrong)

    Also please help me with these 2 questions:

    1- Given that the flow rate is enough for the job, how can I increase the fan total pressure ? (is it only through increasing rpm?)

    2- If I increase the filter area, does it decrease the pressure loss? If yes, how do I calculate the amount of extra filter area?

    Any hint or advice is appreciated. I'm absolutely stuck :confused:

    Thanks in advance
  2. jcsd
  3. Aug 23, 2014 #2


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    2017 Award

    Staff: Mentor

    For a given fan, yes. What else could you change?
    Probably, as the flow rate per area would go down. How much? That depends on the geometry. Is more frequent cleaning an alternative?
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