Miscellaneous Mechanical Components
FILTERS AND STRAINERS
In the filter assembly illustrated in Figure 21, the cartridges are held between plates so that the
Figure 20 Typical Multi-Cartridge Filter
water must pass through the layer of yarn to reach the filter outlet. The type of yarn that is used
depends on the application. Some of the fibers commonly used include resin-impregnated wool
or cellulose, cotton-viscose, polypropylene, nylon, and glass. In some applications that involve
high temperatures or pressures, porous metal cartridges are used. These cartridges are usually
made of 316 stainless steel, but inconel, monel, and nickel are also used.
Depending on the fiber or metal that is used,
Figure 21 Cartridge Filter
cartridges are available that will filter out all
particle matter down to a specified size. For
example, a certain cartridge might be
designed to remove all particles larger than
10 microns, one micron, or even 0.1 micron.
(A micron is 10-3 millimeters.)
Cartridge filters have the advantage of being
relatively inexpensive to install and operate.
Instruments measure the differential pressure
across these filters to let the operator know
when a filter is plugged and must be
replaced. When the cartridges are removed
from radioactive systems, the radiation levels
can be very high.
For this reason, the
cartridges may be withdrawn into a shielded cask for moving to a storage area or a solid waste
processing area. When the porous metal cartridges become plugged, they can be cleaned
ultrasonically and reused. When this is done, the cleaning solution becomes contaminated and
must be processed as liquid radioactive waste.