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.

Chart 1

For Model 44, 66 & 88

Use chart to determine the pressure drop through the housing.  Select GPM - go up to connection size - left to pressure drop.  I.E.: 80 GPM - 2" connections = 0.8 PSI

For multi rounds see below.

Information for chamber sizing

Chart 1

For Model 1818 - 4848

Use chart to determine the pressure drop through the housing.  Select GPM - go up to connection size - left to pressure drop.  I.E.: 2000 GPM - 10" connections = 4.3 PSI

Chart 2

Use chart to determine the pressure drop through the clean filter bag.  Select GPM per square foot of surface area - go up to micron size - left to pressure drop.  I.E.: 60 GPM - 100 microns  = 0.2 PSI

Multiply above by viscosity correction factor (as required).

 Chart 3 Conversion Formulas Viscosity in Cps. Correction Factor 50 4.5 Cps. = Centipoise 100 8.3 Cps. = Centistoke x Specific Gravity 200 16.6 Cts. = Centistoke 400 27.7 1 GPM = .133 Cu. Ft./Min. 800 50.0 1 GPM = 8.022 Cu. Ft./Hr.. 1000 56.2 1 GPM = 3.78 LPM 2000 114 1 GPM = 3,785,000 Cu. Cc./Min 4000 161 1 gallon of water = 8.3 pounds 6000 250 1 PSI = 2.038 In./Hg 800 325 1 PSI = .0689 Bar