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Relationship between differential pressure and airflow through a filter

  1. Apr 12, 2012 #1
    I have a question regarding the relationship between differential pressure across a filter, the airflow through the filter and the size of the orifice that the aire is moving through. I would like to be able to predict differential pressure required to maintain a constant airflow as the filter I am using blocks over time.

    I am having trouble finding a suitable expression online and Filter Manufacturers do not supply this information with their filters.

    Can anybody tell me if there is a simple expression which can be used please?

    Thanks in advance to anybody who can assist me!

  2. jcsd
  3. Apr 12, 2012 #2


    User Avatar

    Staff: Mentor

    Welcome to PF!

    I'm sorry, but this can't work because you have one unknown driving the other: You would have to know the loading of the filter to find the pressure drop on a table or via a formula but the only way to measure filter loading is by measuring the pressure drop!

    What you need is to maintain a constant dp across a device known to be fixed, such as a cooling or heating coil. Then the pressure across the filter can fluctuate while keeping the airflow constant.
  4. Apr 13, 2012 #3
    Thanks for the welcome Russ. I am not an engineer so I am taking time to get through things that probably seem very basic.

    In relation to the pressure drop and loading I am working through correlating the two through measurements.

    I am using a vacuum pump to generate the flow through the filter but cannot control the pressure or loading accross the filter. I know the pressure before and after the filter but not the airflow. Am I dealing with too many unknowns? Thanks for your help.

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