Pump Filters / Strainers
by Tom Hansen, P.E. | ©Dultmeier Sales
There are a large variety of pump filters & strainers used in liquid transfer & spraying systems. The main function of a strainer is to "strain" large and small particles from the liquid before it enters key components in the system such as certain types of pumps, meters and storage tanks or truck tanks. While centrifugal pumps can generally handle 1/4" or 3/8" solids without damage, many other pumps such as gear pumps, piston & plunger pumps, injection pumps and others cannot tolerate even very small particles. Therefore, locating a strainer on the suction side of those types of pumps is critical in protecting the pump from damage. On the other hand, many centrifugal pump applications have a strainer located on the discharge side of the pump to protect the meter and to keep particles from entering the final storage tank. All strainers have screens inside them. These strainer screens are usually easy to remove so they can be cleaned periodically. Screens come in variety of mesh sizes, usually ranging from #6 mesh (6 x 6 squares per inch of screen) to 12 mesh, 20 mesh, 40 mesh, 60 mesh, 80 mesh, 100 mesh and even 200 mesh screens. Most all strainer mesh screens are constructed of stainless steel for corrosion resistance. If the application requires a finer mesh than #200, then most operators use a filter instead. Filters can eliminate fines down to 1 or 2 microns in size.
The most common type of strainer is the "Y" Style Strainer. These can vary in size from 1/2" to 12" or larger and in a variety of materials.
- Banjo Polypropylene Y Strainers (3/4" - 3")
- Banjo LSQ Style (Quick Cleanout) Polypropylene Y Strainers (1-1/2" & 2")
- Watts Cast Iron Y Strainers (Flanged or Threaded)
- Morrison Bros. Cast Iron Y Strainers
- Brass Y Strainers
- Stainless Steel Y Strainer
- Paget Ductile Iron Y Strainers for LPG, NH3, Steam & other high pressure applications.
The second most common type of strainer is the "T" Style Strainer; this type of strainer is more compact than Y Style Strainers.
Basket Style Strainers
Another style of strainer is the high capacity Basket Style Strainer. We offer this style of strainer from Miller-Leaman called the Thompson Filter. These are really strainers, not filters. Screen sizes for the Thompson Strainer range from 1/4" perforated round holes to 100 or even 200 mesh screens. These strainers include very large conical shaped screens with large surface areas for high flowrates at low pressure drops. They also include bottom clean-out ports and are constructed of stainless steel.
Another key style of strainer is the Endline Strainer. These strainers are usually located on the end of suction pipes or hose that are pulling liquids from ponds, pits or below ground tanks. Endline Strainers are meant to prevent larger solids and debris from entering the suction hose, not finer particles so a second strainer like the styles noted above will likely be needed to protect some types of pumps, meters, etc. in the liquid system. Another version of the Endline Strainer is the Bottom Hole Skimmer.
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