Water pumps are commonly used on construction sites to remove excess water accumulated due to heavy rain or high water table. They primarily serve two purposes: keep water out of foundations, tunnels, and other excavations pits; and provide a supply of water for jetting and sluicing, pumping water for cofferdams, etc.
The choice of water pumps for construction sites is dependent on the complexity of the project, the amount and rate at which the liquid is removed, the type of liquid, the loss due to friction, the height of suction lift, and the size of the pump.
This article explores the important types of pumps used for construction sites and the factors to consider while choosing the right water pump.
Factors Affecting Selection of Water Pumps for Construction Site
Factors that govern the selection of water pumps are:
- Power of the pump
- Material of the pump
- Motor type or fuel type of the pump
- Head required by the application
Types of Pumps for Construction Sites
The different types of pumps used for construction are:
- Centrifugal pumps
- Displacement pumps
- Submersible pumps
- Air-lift pumps
1. Centrifugal Pumps
A centrifugal pump consists of a rotating impeller that moves water into the pump and discharges it. The rotating impeller creates a vortex as a result of which air is taken from the external environment and the developing atmospheric pressure causes the water to rise through the pump.
All the liquids can be pumped using a centrifugal pump irrespective of their viscosity. These pumps work efficiently even with thin liquids.
In certain situations, the casing of a centrifugal pump is filled with vapors or gases that inhibit pumping. Such situations demand the priming process. Priming is the process of filling the casing of the pump with liquid before starting the pump. There are self-priming centrifugal pumps that have water in reserve within the impeller chamber.
Centrifugal pumps can be electric, hydraulic, gas-powered or manual type. These are often used in tunnel and foundation construction pits to handle oil, sludge and sewage.
Properties of Centrifugal Pumps
- Centrifugal pumps are employed to pump water in facilities where pneumatic systems are compatible, and there is no requirement for suction lift.
- It is used to pump water from domestic wells.
- Centrifugal pumps convey continuous pressure source for the fire protection system. It can help enhance the pressure in water intake lines.
- These can act as a sump pump in either vertical or horizontal configurations.
- Centrifugal pumps require recirculating liquid to prevent the issues due to overheating. This is mainly caused due to low flows.
- Proper operation of centrifugal pump requires priming.
2. Displacement Pumps
Displacement pumps can be classified into:
- Reciprocating pumps
- Diaphragm pumps
2.1. Reciprocating Pumps
Reciprocating pumps work based on the movement of the piston in a cylinder. Large reciprocating pumps possess 2-3 cylinders. When the piston moves in one direction, the water is drawn into the cylinder. When the piston moves to the rear end, the water is pushed out.
Reciprocating pumps gain high efficiency and are reliable. They can pump the liquid at varying heads with uniform discharge. These are best suitable for low-flow conditions.
2.2. Diaphragm Pumps
Diaphragm pumps work by drawing water into the cylinder during the raising and lowering of a diaphragm. When the diaphragm moves out, water is sucked into the cylinder. As it moves down, it is discharged to the delivery pipe.
Diaphragm pumps can deliver liquids that contains 10 to 15% solids and can work with water with varying flow characteristics.
3. Submersible Pumps
Submersible pumps or sump pumps or electric submersible pumps (ESP) lowers the groundwater and remove water from a deep sump. The pump unit consists of a sealed motor close-coupled to the pump body. The whole unit is submerged in the fluid to be pumped.
The sump pump consists of a centrifugal unit and a motor mounted in a single cylindrical unit as shown in Figure-3. There is a space between the pump and casing that facilitates the movement of water up to the rising main.
Submersible pumps are used for heavy-duty pumping in construction which mainly involves lifting of gritty water.
4. Airlift Pumps
Airlift pump, as shown in Figure-4, consists of a vertical pipe that is submerged in a well in such a way that a major portion of the pipe lies below the water level. Compressed air is blown to the lower point through an air inlet. The air at the bottom carries the water up the pipe and finally to the delivery area. Airlift pumps are mainly used for moving silt from the base of a cofferdam.
FAQs
Factors that govern the selection of water pumps are:
1. Power of the pump
2. Material of the pump
3. Motor type or fuel type of the pump.
4. Head required by the application
Diaphragm pumps can be used to deliver liquids that contains 10 to 15% solids and can work with water with varying flow characteristics.
Submersible pumps are used for heavy-duty pumping in construction which mainly involves lifting of gritty water.
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Comparison between Centrifugal pumps and Reciprocating Pumps