Miscellaneous Mechanical Components
FILTERS AND STRAINERS
The flush source is then opened and the flow goes into the outlet of the strainer or filter, through
the strainer or filter, and exits the inlet to the backwash drain or waste tank, carrying the debris
The important information in this chapter is summarized below.
Filters and Strainers Summary
A cartridge filter may be a single cartridge or multi-cartridge filter. The
cartridges are cylinders that usually consist of a fiber yarn wound around a
perforated metal core. The liquid being filtered is forced through the yarn and
then through the perforations in the metal core to the filter outlet, which can be
at either end. This type of filter is used to remove fine particles in any flow
condition. Radioactive systems may use these because they are inexpensive and
easy to replace.
Precoat filters consists of a filter housing that contains a bundle of septums,
(vertical tubes, on which the filter medium is deposited) usually made of
perforated or porous metal (normally stainless steel), porous stone, or porous
ceramic material. The filtering medium fibers may be finely divided diatomite,
perlite, asbestos, or cellulose. Diatomite, the least expensive medium, is used to
filter liquid waste that will be discharged from the plant. Cellulose is generally
used for processing water that will be returned to the reactor, because diatomite
can allow silica leaching.
A deep-bed filter is based on a support screen (decking), which is mounted a few
inches above the bottom of the tank. The screen is perforated to allow water to
flow through it. A coarse, aggregate layer of crushed rock or large lumps of
charcoal is placed on top of the screen, and the deep bed itself (2 to 4 feet of
granular anthracite or charcoal) is placed on top of the aggregate. This type of
filter is frequently used in raw water treatment.
The bucket strainer is literally a bucket to catch debris. The bucket can be
removed for cleaning by loosening the strongback screws, removing the cover,
and lifting the bucket out by its handle. It is usually used in systems expected to
have larger debris.