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Fine Straining Applications
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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.
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How to Choose the Right Strainer Basket
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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.
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Basket Cleaning
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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.
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Baskets for Large Size Strainers
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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.
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