The
basket is the heart of a strainer since this is where the unwanted material
is trapped. Strainer baskets are made of perforated sheet metal and a wide
range of opening sizes is available. The size of the basket perforation
should be slightly smaller than the minimum particle size to be removed.
Using a smaller perforation opening than necessary only means the basket
will fill and clog more quickly and have to be cleaned more often. Well
made strainer baskets should be brazed or welded. The use of solder to
hold the basket together cuts the cost, but it is not recommended. Soldered
baskets are inherently weak and can break easily.
2
Fine
Straining Applications
If finer
straining is needed, then the gasket is fitted with a wire mesh liner inside
the perforated sheet. Here the mesh lining does the actual straining, while
the outer metal sheet acts only as a mechanical support. For this reason
mesh lined baskets are generally supplied with an outer perforation having
about 50% open area. This gives the best combination of maximum flow rate
with the least loss of strength. Perforated materials with more than 50%
open area are too weak to provide adequate mechanical support for the mesh
lining. It is important that the wire mesh be integrally and tightly fastened
at the tip and bottom of the basket, other wise material can bypass the
mesh lining by getting behind or under it. For this reason baskets with
removable mesh lining should be avoided. A mesh lined basket should be
a one piece welded unit.
3
Basket
Cleaning
Baskets
should be handled carefully. They should be cleaned by using a brush or
by soaking them in a solvent or cleaning solution. They must not be rapped
on table or struck to loosen something in them. This will cause them to
dent out of shape and eventually their welds will break. It is a good idea
to clean baskets promptly after removing them from a strainer. It prevents
the product from drying and hardening and thus becoming harder to clean.
Most important, a spare basket should be on hand for every strainer. Baskets
have a habit of breaking at the most inconvenient times and the strainer
cannot function unless there is a replacement.
4
Baskets
for Large Size Strainers
As strainers
become larger, obviously the size of the basket increases. When baskets
get too large they become too heavy to be easily handled. Also, considerable
headroom is needed above the strainer to removed the basket and this can
be a problem where height above the strainer is limited. A simple way to
solve this problem is to use several smaller baskets in place of one large
one. A more compact, workable design is achieved with no loss in dirt handling
capacity.
Basket
Strainers - How to Choose
