Coarse Strainers
Coarse Strainers
Designed to operate automatically and reliably in the most arduous of conditions, this robust design utilises tubular arrays of welded, wire-wound strainer elements.
The filter elements have a wedge shaped, slotted filtering surface and service flow is from inside to outside of the elements. The narrow slots between the wedge shaped etchings allow only two-point contact of any removed suspended solids, and thus backwashing is much more effective than for woven wire mesh designs.
Regular automated backwashing ensures that the wedge wire elements are flushed with a water velocity of more than twice the forward flow velocity, ensuring that a vigorous release action is provided for the best possible cleaning process. This is highly effective against the stickiness of many bio-growths including plankton and jelly fish.Backwash flow rate is controlled by a simple restriction orifice which ensures consistent and repeatable results.
Backwashing occurs while the vessel remains on-line and in full 100% operation, eliminating the need for vessel isolation at any time. The backwash cycle duration is very short and completed within 1 to 3 minutes depending on the size of the unit. The time intervals between backwashes are recommended to be 1 to 3 hours to avoid any build-up or sticking of solids.
No backwash water losses are encountered as the reverse flowpath is fully sealed during operation, ensuring that all the backwash water passes through the filter screen with none being drawn from the inlet side of the screen around the backwash head.
The thick-walled rotating internals are robust and resistant to corrosion and are spring-balanced to unsure that the upper and lower nozzles are held firmly against the low-friction rubbing plates.
Multiple vessels can be packaged together on a single skid to provide high flowrates and in-place standbys if desired, however it is always recommended that all vessels are maintained in operation to avoid issues arising for stagnant conditions inside any off-line and isolated vessels.
