In my experience, T strainers were used as start-up strainers where very little debris was expected. At the first shutdown, the basket could be removed and the flange replaced, leaving a straight-through, low-resistance flow path. Basket strainers were generally installed in pairs with valving such that one could be cleaned while the other was on-line.

Strainers

The Question:

Pump Suction Strainers, Which is best?

My answer:

That is a very good question. The selection of a strainer depends on many factors. These include purpose, operating philosophy, maintenance philosophy, commodity, entrainment, space and cost.

There are four basic configurations (types) and they each have positive and negative points. The common types are listed below in alphabetical order along with some comments about selection.

Basket Strainers

http://www.fabrotech.com/std_bk.htm (Simplex)

http://www.fabrotech.com/duplx.htm (Duplex)

The Basket Strainer is normally fabricated and can be found in a wide range of sizes and materials. The larger sizes will come with legs for support (reduces loading on pump nozzles). The larger sizes require davits or monorails to remove the basket. Depending on the commodity they should also be located in a paved, curbed well drained area for removal and cleaning. Removal and re-installation of the basket does not normally effect the pump alignment. The available "cross-sectional area" choices depend on the screen selected. The Duplex Strainer allows for full operation on one strainer chamber while the other side is in full operation.

Cost: Highest total installed cost.

Cone Strainers

http://www.weamco.com/cone.htm

The Cone Strainer is normally a prefabricated, off-the-shelf piping item. They come in two basic configurations: the pointed cone and the truncated cone. They are available in various materials and open cross-sectional area. The Cone strainer may be used as a permanent strainer but is normally used only during start-up and in then removed. The minimum recommended cross-sectional area is 150% to 200%. This means that if you choose a 150% strainer and it gets one third plugged you still have 100% of your pump suction line cross section area open. With the 200% it gets one third plugged you still have 100% of your pump suction line cross section area open. With the 200% strainer if it gets one half plugged you still have 100% of your pump suction line cross section area open. It all depends on how dirty the product is and how you intend to maintain the strainers. Removal and/or installation will normally require the services of a Millwright to check or realign the pump. A critical piping layout issue is the space requirements (example: 12" pump suction line, pointed cone, 200% open area = 33" long)

Cost: Lowest total installed cost.

TEE Strainers

http://www.fabrotech.com/teestr.htm

The TEE Strainer is a strainer fabricated from a standard piping TEE. The end-to-end dimensions are the same as a standard TEE. They are available with butt-weld ends or with flanged ends. The screen removal cover can be flanged or quick release toggles. TEE strainers also come with the "flow" in one end and out the other (screen removal from the branch) or in one end and out the branch (screen removal from the end). The removal or installation of the screen does not affect the pump alignment. The available "cross-sectional area" choices depend on the screen selected.

Cost: Higher than Cone but lower than Basket

"Y" Strainers

http://www.fabrotech.com/c_carb.htm

The "Y" Strainer may be cast steel or fabricated. The "Y" Strainer is designed to allow for in place "blow-down" cleaning. Depending on the commodity and the "blow-down" piping this strainer can be cleaned while in full service. The "Y" Strainer is available in various end connection choices including screwed, socket-welded, butt-welded, flanged and mechanical-joint. The "Y" Strainer also comes in a wide range of sizes from very small to 24". The "Y" Strainer only comes with the flow in one end and out the other.

Cost: Higher than Cone but lower than Basket

All of the above: http://www.pelmareng.com/pdf/Filters/Fabricated_Strainers.pdf