Technical Sizing Information for Bag Filter and Filter Housings

Sizing of a liquid filter strainer / bag filter housing is a straight forward method. The required flow rate of filtration and the particle size retention are used to determine the pressure drop through the combination of the housing and the strainer or bag. The Chart 1 below gives the pressure drop through the housing - the connection size of the housing is of greatest concern. The Chart 2 gives the pressure drop through the strainer or bag filter. This chart is based upon the surface area of the strainer. The flow rate per square foot surface area is determined by dividing the total GPM by the surface area. The pressure drop is the relationship of the GPM per square foot surface area and the strainer hole size (micron retention). Charts are based water with a viscosity of 1 centipoise. Multiply the pressure drop by the viscosity correction factor (Chart 3) to determine the actual pressure drop for liquids other than water.

The pressure drop will be used in pipe sizing and pump sizing. If used on the suction side of a pump, the pressure drop must be low to prevent causing pump cavitation. I would suggest keeping under 1 PSI in most cases.