Slotted wedge wire is constructed
by helically winding a continuous triangular-shaped wire around a series of vertical
stringers. They are welded to the stringers at measured spacing to form an independently
strong element. One of the flat sides of the tri-angular wire is the circumference of the
element giving it an overall smooth surface. This improves both manual and backwashing
cleaning. This is usually the best element in terms of backwash cleaning efficiency
resulting from a venturi effect at the screen openings. Slotted screens have proven best
for applications with fibrous solids.
Fibers have a tendency to get trapped flat against the side of the element. This can allow
the ends to go through separate screen openings and trap the fiber. Backwashing is
generally unsuccessful in dislodging the fibers because the ends of the fiber flatten
against the inside of the element. This holds the fiber on the element as a staple is held
in paper. Slotted elements retard this "stapling" and are preferred to mesh
screens for this service.
Because of the durability of slotted wedge wire elements, they are specified for critical
service applications where it is not feasible to remove the element periodically for
routine inspection. An example would be in petroleum refinery applications where the
filters are used on continuous, high temperature, high pressure applications. The higher
the cost of slotted elements is also easy to justify for remote installations where
extraordinary long screen life is vital.
Slotted elements are not used for removal of flake shaped solids that can align with the
slots and pass the element. The other disadvantage of slotted elements is that they have
less open area than mesh screens in middle and fine retention ranges. This means that more
equipment would be required than in a comparable application where wire mesh would work
just as well.
RPA Process Technologies
9151 Shaver Road
Portage, MI 49024
Toll Free (US only):
1-800-656-3344
Voice: +1 269 323-1313
Fax: +1 269 323-0065
www.RPAprocess.com
info@RPAprocess.com
