ECONOMYGENERALTECHNOLOGY

The ins and outs of basket strainers

A basket strainer is a device that uses a mesh screen to filter out foreign particles in a horizontal pipeline. These particles are then removed from the chamber. Basket strainers are a device typically connected to a pumps suction. This is used to filter out solids or debris larger than the mesh area from which the liquid matter has to pass through.

How they are used typically

A Basket Strainer can be defined as a pipe fitting through which liquid is passed for purification, filtering or separation from solid matter; anything used to strain a liquid; any device functioning as a sieve or filter used to prevent solid bodies from mixing in a liquid stream or flowline. Strainers arrest pipeline debris such as scale, rust, jointing compound and weld metal in pipelines. The protecting equipment and processes from their harmful effects, thus reducing downtime and maintenance. Use of rightly selected strainers at correct locations (usually upstream) is a must to protect expensive and critical downstream equipment such as pumps, flow meters, steam traps, control valves etc.

The main different types of strainers to take note of

T type or Basket type or Pot type strainer is characterized by a vertically orientated chamber. It is typically larger than that of a Y-type strainer. Size for size, the pressure drop across a basket strainer is less than that across the Y-type. This is as it has a greater free straining area. It makes the basket type strainer the preferred type for liquid applications. As the dirt holding capacity is also greater than in Y-type strainers, the basket type strainer is also used on larger diameter steam pipelines.

Basket type strainers can only be installed in horizontal pipelines, and for larger, heavier basket strainers, the base of the strainer needs to be supported. To service a basket type strainer, the cover can be removed. This is all so technicians get immediate access to the filtering element if it needs replacement (due to accumulated debris). When basket type strainers are used on steam systems, a significant amount of condensate may be formed. Consequently, strainers designed for use in steam systems usually have a drain plug. From here, they can be fitted with a steam trap to remove the condensate.

Filters versus strainers – what you need to know

A filter is a device that removes particles from a given liquid or gas. It includes a disposable medium for removing particles of specified micron sizes. All strainers are filters, but all filters are not strainers. A strainer is only one type of filter. Strainer uses a perforated plate or screen mesh to remove larger particles from a process stream. The major advantage of a Strainer is that it is reusable. The filter screen is only used once and must be changed when it clogs. The main difference seems to be in diameter of the holes in the media screen also termed as mesh size in case of strainer.

There is no hard and fast size division to define strainers from filters. Filters capable of removing particles as small as 1 μm are available Another difference is resistance. Strainers normally present low resistance to liquid flow. The pressure drop across most strainers is relatively small. This is when compared with the pressure drop across thick media filters or membrane filters. Another difference is the function. A strainer is used to protect other downstream equipment (e.g., pumps, instrumentation) from damage by rogue junk. A filter is employed to separate particles from the fluid.

Overall

Industrial basket strainers are made to remove solids from liquids that are being processed. Typically, they are made of a wide variety of alloys. So the right material can be chosen to meet the demands of the filtration job. These strainers are also extra-strong. This is so that they can operate at full line pressure even under high volumes and long run times. There are no end of ways to which they can and do add no end of value to the end user.