Automatic Strainers and Filtration Systems

FLUSHING BASKET STRAINERS are a type of modified simplex strainer, having the drain port connected to the bottom of the strainer basket, enabling "flushing" of retained particles when the drain valve is opened.  The effectiveness of the cleaning is dependent upon the differential pressure of the system compared to the  (presumably) atmospheric pressure of the drain port.  Other factors include the particle characteristics; if they tend to be hard and non-deformable, this strainer design provides a low-cost approach for reducing labor related expenses.  Most designs are modified cast strainers, thus pricing and lead time are low.

BACKWASHING BASKET STRAINERS use some of the fluid already strained to dislodge particulate embedded within the filter element.  This is accomplished by effectively reversing the flow through the element and out the drain port using an internal nozzle assembly which slowly rotates within the element.  Approximately 5% of the flow is used for backwashing the filter element and the duration of the cleaning cycle is typically 3-5 minutes.  This style strainer supports flow rates typical of pipeline sizes from 2" to 48" and due to the backwashing nature, are mostly used for applications using water.

MECHANICALLY CLEANED STRAINERS are a design pioneered by Ronningen-Petter (now owned by Eaton) are used mostly for non-water fluids or for applications where it is important to minimize product loss.  Very often these fluids are either viscous or hazardous such as paint, wax, petroleum products and food/beverage applications.  An internal disc wipes the surface of the element, pushing all of the retained particles to the purge chamber.  When the drain valve is opened, the system pressure flushes the particles out the drain.  The cleaning cycle is typically <1 second and the volume of solids/fluid <1 gallon.  The internal stroke frequency and the purging frequency are set with programmable timers.

TUBULAR BACKWASHING FILTER SYSTEMS are another design pioneered by Ronningen-Petter and are used for applications requiring fine particle retentions (as fine as 100 mesh [150 microns]).  Tubular backwashing filter systems temporarily reverse the flow through the filter element to backwash and dislodge embedded particulate to a drain port.  When continuous flow is required, the filter system will consist of multiple chambers, ensuring that a minimum flow and a constant discharge pressure is maintained during the cleaning cycle.