Engineers who work on systems of fluid going through strainers or filters need to know how to determine a clean pressure drop. This is the decrease in pressure resulting from fluid being forced through a clean, unclogged strainer. Knowing the clean pressure drop is a starting point for extrapolating the pressure drop when a system is clogged to varying degrees. To find the clean pressure drop, you must know the perforation size of the filtration, the strainer size and the flow rate.
- Graph of flow rate vs. pressure drop for various strainer/filter sizes
- Chart showing percent open area for various screen types/dimensions
- Chart showing correction factors for various screen opening sizes
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Instructions
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1
Use the flow rate and the strainer size to look up the pressure drop on the graph. Follow the diagonal line that corresponds to the strainer size until you are at the horizontal coordinate for the flow rate. Then find the vertical coordinate at this point, which gives you the pressure drop, usually in psig (pounds per square inch).
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2
Use the chart to find the percent open area for the given screen size. Then use this percentage in the other chart to find the correction factor for that screen size with that percentage open area.
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3
Multiply the pressure drop by the correction factor. This gives the clean pressure drop, still in psig since the correction factor is a unitless value.