Propeller pumps: Two basic types.
Axial-flow pumps have flow parallel to the axis of the impeller.
Mixed-flow pumps have flow that is both axial and radial (perpendicular to the shaft) to the impeller.
Reciprocating or Piston pumps
Pumps used to move sludge by a piston that moves back and forth. Reciprocating pumps should never be allowed to pump against a closed discharge valve due to a build up of pressure that could damage the pump and/or the piping.
Incline screw pumps
An auger type pump housed in a trough that is on an incline. The auger is supported by bearings on both ends. The screw or auger operates at a constant speed moving the wastewater up the trough to a point of discharge. These are commonly used on influent and effluent waste streams where low lift, high capacity, non-clog pumping is required. They may range in size from 12 to 144 inches in diameter with rated capacities from 100 to 70,000 gpm. They are primarily suited for lifts up to 25 feet but are available for higher lifts.
Progressive cavity pumps
These are similar to incline screw pumps except that the screw shaped rotor is enclosed in a housing (stator). The spacing between the rotor and the inside casing walls form a series of cavities. As the rotor turns, the threads make contact with the walls and move the water along in auger fashion. The size of the cavities along the rotor determines the capacity of the pump. These pumps are recommended for liquids containing higher concentrations of solids. Like reciprocating pumps, they should never be operated dry nor against a closed discharge valve.
Pneumatic ejectors (Air Lift)
An air lift ejector consists of a receiving container, inlet and outlet check valve, air supply, and liquid level detector. When the wastewater reaches a preset level, air is forced into the container, ejecting the wastewater. Following the discharge cycle, the air supply is cut off and wastewater flows through the inlet into the receiver. With flow ranges from 30 to 150 gpm, they are mostly used for pumping raw wastewater. These pumps are capable of passing solids up to the size of the inlet and discharge valves since there is nothing on the inside of the ejector-receiver to restrict the flow. They are, however, a high maintenance problem. If a stick or other object gets stuck in either check valve, the ejector will not operate.
These pumps are used to measure a quantity of substance that is being pumped into the system. These pumps can be used to add hypochlorite, peroxide, and other chemicals such as odor controlling liquids to the collection system.
Calculate the Time it takes to Pump out a Tank
If two 337.5 gpm pumps are used how, long will it take in hours to de-water a rectangular tank. 60 feet long by 35 feet wide and 14 feet deep?
First calculate the volume of the tank and convert to gallons.
Volume = 60 ft x 35 ft x 14 ft = 29,400 ft3 = 29,400 ft3 x 7.48 = 219,912 gallons
Divide the pump rate by the number of gallons to find the time. Convert to hours.
(219,912 gal) / (675 gal/min) = 325.80 min
(325.8 min) / (60 min/hr) = 5.42 hrs
Calculate Horsepower and Kilowatt Hours
A pump has a capacity of 2500 gpm and it uses 55 kilowatts. Pump efficiencies average 90% for this size pump, what size horsepower motor is required?
You will calculate the horsepower of the pump that is required by using the kilowatts equation.
Hp = (kilowatts X Efficiency) / (0.746)
Hp = (55 kilowatts X 0.90) / (0.746) = 66.35 Hp is the minimum Hp needed for proper operation