Automatic Strainers Self cleaning basket strainers

utomatic strainers are a cost effect alternative to duplex strainers for high flow rate applications which would complicate removal and cleaning of large (heavy) strainer baskets as well as for applications that might have varying solids loading conditions. For example, automatic strainers are ideal for raw water intake pump suction strainers that might see higher particle loads after a rain storm. Backwashing strainers are also used for remote locations where servicing simplex and duplex basket strainers would be difficult.

Although we can supply automatic strainers with mesh lined elements for retentions as fine as 75 microns, they are best suited for coarse retentions in the ¼” range and perhaps as fine as 100 mesh (150 microns). Due to the volume of process fluid used for cleaning, these strainers are almost exclusively used for water filtration; our standard materials of construction include cast iron, carbon steel and 316SS and for warm sea water applications we’ll use an alloy like Hastelloy.

Principle of Operation

Filtration Mode
Flow enters the strainer body and must flow upwards into the strainer element, passing through it’s perforated or mesh lined surface and exiting the vessel through the outlet nozzle. The element is stationary and particulate that cannot pass through the element either falls to the bottom of the vessel or is lodged against the perforated or mesh lined surface of the element.

Backwash Mode
The backwashing cycle is actuated either by manual override, differential pressure or programmable timer. Once it begins, simultaneously a draining valve opens and a motor atop of the strainer begins rotating a hollow shaft within the portion of the strainer that contains the filter element. Attached to this hollow shaft is a vacuum nozzle which extends just above the inner surface of the filter element.

Internal view of Eaton model 2596 backwashing strainer

As this nozzle sweeps around the interior circumference of the filter element the resulting differential pressure (system pressure vs. atmospheric pressure) causes the clean, filtered fluid to revers flow through that section of the element, dislodging any material stuck to the inner surface of the element and its vacuumed through the hollow nozzle shaft, exiting the system via a backwash drain.

The motor has sufficient torque and the nozzle arm is designed to break-up debris such as sticks and other organic material that might accumulate onto the filter element surface.

Backwashing of a model 2596 strainer element

Periodically it might be necessary to open the strainer body and remove large debris that may have settled to the bottom of the strainer; the straining element and backwash nozzle assembly is attached to the top section of the strainer, so it can be easily lifted for strainer element inspection and cleaning-out the bottom as needed. We can also install a man way in the body to facilitate inspections and clean-out without having to disassemble the strainer.

Please send us mail on info@pipelineproductsonline.com along with your pipeline size, we will try to reply/quote you within 48 hrs .