Introduction to Basket Strainers

Strainer and Filter Differences

What is the difference between a strainer and a filter? Actually there isn’t any since a strainer is, in reality, a coarse filter. The question is then one of semantics. Generally it is assumed that if the particle to be removed is not visible to the naked eye, the unit is filtering, and if the particle is visible, the unit is straining. The average human eye can detect a specific particle between 50 and 70 micros. Most people cannot see anything smaller than 325 mesh, or 44 microns. Since 200 mesh is equivalent to 74 microns, a general rule would be that if the screening device is coarser than 200 mesh, it is a strainer and if it is finer than 200 mesh it is a filter.

One of the best uses for a strainer is in conduction with a filter. By installing a strainer directly ahead of a filter, the large heavy pieces which would quickly clog the filter are removed. The filter is then free to do its major job of fine particle removal and does not have to be cleaned so often.

How They Can Improve a Process

The problem of unwanted material in pipelines is a never ending one. Whether the flowing material I seawater, oil, paint or a variety of food or chemical products, there is often something present that can cause trouble. Dirt, foreign matter, or even clumps of the product itself can clog or damage pumps, spray nozzles, condensers, and similar equipment. Sometime a finished product has to be rejected because of the presence of undesirable solid matter.

Basket strainers remove unwanted particles from pipeline flow. Furthermore they are relatively inexpensive compared to the equipment they protect or compared to the down time, inferior products, or loss of production if they were not doing their job in the piping system.

Just What is a Basket Strainer?

An official definition adopted by the Fluid Controls Institute is : “A closed vessel with cleanable screen element designed to remove and retain foreign particles down to 0.001 inch diameter from various flowing fluids.” Note the term “foreign particles”. Strainers do not necessarily remove only dirt. They take out material which is not wanted in the fluid and this can sometime be a valuable product which may be saved.