Web Exclusive: How to Select the Right Pump
April 28, 2010
A typical customer may ask for a diesel driven 6-inch
pump capable of pumping 1,400 gallons per minute (GPM). But there are
multitudes of pumps that will meet this requirement. Just because it’s a 6-inch
pump doesn’t mean it’s equal in performance to all 6-inch pumps. Say the
customer was a little more specific and stated they wanted 1,000 gallons per
minute at 150 feet of head. While that customer provided more information than
the size of the pump, it's not enough. If a typical end suction centrifugal
pump is rented by a generic rental company and the application is a sewage
bypass, a sewage spill may occur. This is because a typical end suction
centrifugal pump is not meant to pump sewage. A more appropriate pump would be
a diesel-driven trash pump or nonclog pump that is designed to handle sewage
and solids.
Other
factors that must also be considered is the size of the suction and discharge
lines, pressure ratings and valves required. In highly critical projects, it is
better to contact specialty contractors who typically use and are more familiar
with all types of pumps in everyday field operations.
A wellpoint pump is designed to have the highest air handling capacities on the market.
Wellpoint Pump
- Designed to pump clean water/effluent for a wellpoint dewatering system and lowers the groundwater table to drain construction excavations
- Designed to have the highest air handling capacities on the market and can pump water while sucking air without shutting the pump down
- Capable of pumping 1,500 gallons per minute with 145 feet of head
- Must pump relatively clean water
- Best used for wellpoint dewatering and sock dewatering
A trash pump can pump sewage or sandy water.
- Designed to pump clean or dirty/trash-laden effluent
- Used to pump sewage or sandy water
- Handles clean, muddy, mucky or sandy water with solids up to 3 inches in diameter
- Incorporates an open impeller and wear plate
- Capable of pumping 1,500 gallons per minute with 125 feet of head
- Widely used because of their reliability and versatility
- Best used for flood drainage, sewage bypass, pumping polluted wastewater and pumping settled sludge
A jet pump can achieve discharge heads of up to 600 feet.
- Designed to be used as a fire pump, jet casings or wellpoints without drilling/digging
- Used in agricultural irrigation systems and also in mining and quarry applications where high head capacity is required
- Capable of pumping more than 1,400 gallons per minute of clean water with 600 feet of head or more
- Equipped to achieve discharge heads of up to 600 feet
- Best used for quarries/mining, jetting wellpoints, jetting casings, pipe cleaning, pipe testing, water blasting and marine construction
A submersible pump can work in areas that would flood and disable a conventional pump.
- Designed for dewatering applications in construction, mining and sewer rehab projects
- Used in areas that would flood and disable a conventional pump
- Serves as an effective solution for applications with high heads and is not affected by “suction lift limitations”
- Must be pulled out for inspection
- Best used for open pit, lake unwatering, manholes, flood control, mining and sewer bypass pumping.
Q: Need a pump to water with sand or sludge in it?
A: The 6-inch jet pump and the 6-inch wellpoint pump will clog from sludge and stop working; sand will also cause wear and greatly reduce performance. The 6-inch trash pump or 6-inch hydraulic submersible pumps are the pumps you need.
Q: Need a pump with more than 300 feet of head?
A: The 6-inch trash pump, 6-inch hydraulic submersible pump and 6-inch wellpoint pump will fail to push the water half that high. The 6-inch high pressure (jet) pump is the pump you need.
Q: Need a pump that can suck air along with water while pumping?
A: The air will cause both the 6-inch trash pump and 6-inch jet pump to cavitate and even stop pumping. The high air-handling capacity of the wellpoint pump makes it the correct pump for this application.
All of the above are 6-inch pumps, but they all are very different from each other and are designed for different types of jobs. When selecting the right pump, don’t go to the nearest salesman and tell him you need a 6-inch pump; instead, tell him what you need the pump to do. A salesman may give you what he has on the shelf; a pump and dewatering professional will evaluate your application and give you the right tool, drawing from knowledge attained from field experience and application. Field experience cannot be taught; consult a pump professional before selecting a pump for your pumping application.
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