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Thread: Losses in an air-flow system

  1. #1
    Associate Engineer
    Join Date
    Dec 2017
    Posts
    1

    Losses in an air-flow system

    I'm using a diaphragm pump to pull air from a dusty environment and filter it across a 2.5um filter paper material. I'm trying to determine what my losses are in the system, and establish a spec on a new pump such that we get a certain flow rate at the intake.

    For example, I want to do an experiment with a pump we have on hand with three different filter areas (5mm diameter, 10mm diameter, 15mm diameter) to create a curve that tells me how my losses change depending on the area. I will keep everything else the same, like the hose connections, hose length, hose run, etc.

    The pump I have on hand pulls a volumetric flow rate of 10 liters per minute (LPM) without restriction, but I will likely be looking to purchase a new pump with 20 LPM unrestricted flow, but I want to do this experiment to make sure that I get at least 15 LPM at the intake with the new pump, assuming I can use these results to inform that decision.

    What will the relationship be between the losses at the lower LPM pump vs the higher LPM pump. For example, if my loss at 5mm on the 10 LPM pump is 20%, will it also be 20% on the 20 LPM pump, or does it change?

    Hope this is explained clearly. Thanks!

  2. #2
    Project Engineer
    Join Date
    May 2015
    Posts
    109
    your filter is a substantial loss and as soon as you begin filling it with dust the loss increases. Roughly as the pressure difference across the filter changes. To get more air through your without changing the physical size, you also need to increase the pressure differential.

    Investigate a flow meter to determine how much air you pull through the filter.

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