Some users require that the suction specific speed be limited to perhaps 11,000. This limitation may be highly important for certain types of pumps, but if a properly designed impeller is used in a vertical turbine pump application, experience shows that the suction specific speed can range up to 15,000 without creating problems. Range of operation over the pump curve and recirculation possibilities must be considered here. The pumps are either oil lubricated or water lubricated in case of lineshaft pumps and are built mainly to AWWA standards. Submersible motor driven pumps are also used.
Materials are mainly steel, cast iron heads and bowls and bronze impellers.
When pumping fresh water, materials are steel column and head, cast iron bowls and bronze impellers. When pumping brackish or sea water, coated standard materials may be used. Experience dictates if coated standard materials offer acceptable life. Lineshaft pumps that pump water are normally built with a packing box to provide sealing. Lately, however, there have been requests for water pumps built with mechanical seals.