Pumps must be able to move a high volume of water, pass debris without clogging, and withstand difficult conditions on any jobsite. Photo: Multiquip Inc.
Trash centrifugal pumps handle large amounts of debris and are preferred by contractors and municipalities. They commonly range from 2 to 6 inches, producing flows from 200 to 1600 gpm and heads up to 150 feet. They generally handle spherical solids up to one-half the diameter of the suction inlet. Sticks, stones, and debris flow through without clogging, making trash pumps ideal for most jobsites. The initial higher cost is recovered because of reduced maintenance costs.
Trash prime-assist pumps do not have to be manually primed before operation. To prime the pump a vacuum pump or an air compressor removes the air from the suction hose and pump body. The pump then starts dry and reprimes itself. Besides dewatering, the most basic municipal application for these models is sewer bypass. Automatic operation can be added. New technology is also being developed to include telemetry so engine and pump performance can be monitored remotely and alert messages can be sent to cell phones and PDAs. These prime-assist pumps also can be used to move lots of air, such as with well point dewatering systems.
Diaphragm pumps, often called mud hogs, mud hens, or mud suckers, are popular where shallow and slurry water render centrifugal pumps ineffective. They are often used in trenches or excavations where groundwater seeps slowly into the worksite or in areas with high water tables. Diaphragm pumps provide the lowest discharge rate and head of any contractor pump. Most popular are 2- and 3-inch gasoline-powered models producing flows in the 50- to 90-gpm range.
Submersible pumps are compact, feature a streamlined design, and are easy to operate and maintain. No pump provides such a fast return on investment and extended work life. One application is to remove water from city swimming pools and manholes. Typical submersible pumps range from 2 to 6 inches, produce flows from 45 to 790 gpm and heads up to 138 feet.
Because submersibles are used in the water source being pumped, they are not subject to the suction lift limitations of other typical contractor pumps.
Experienced dewatering contractors will opt for pumps with 230/460-V, three-phase motors as they provide higher performance and cost less to run over time.
Know where the pump will be used: Altitudes affect a pump's performance. At higher elevations, atmospheric pressure decreases, reducing suction lift, so the pump should be located as close to the water source as possible. Gasoline and diesel engines also typically lose 3% of their power for every 1000 feet of elevation. Reductions in engine speed trim both flow and head (to read about safe, trouble-free pump operation, click here).
— Maria Hernandez is media manager for Multiquip Inc.