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    A Complete Guide to Water Pumps: Types and Uses

    By on Last modified: August 8, 2022

    Weather extremes in recent years have brought us raging wildfires, extensive and repeated flash flooding, and widespread drought the further you go from the coast. The prolonged summer heat has also meant water restrictions in urban areas and scorched farmland. All instances revolve around water. Getting water to where it’s needed is done with a water pump. There are dozens of different types, and each is better suited for a specific use. Pumps are essential tools in firefighting, agriculture and irrigation, industry, construction and manufacturing, commerce and communal services, and for widespread residential use.  

    What is a Water Pump?  

    water pump taking out water from a river
    Source: mideast.com

    water pump is a tool with one simple purpose – moving large amounts of water from one place to another. And different water pumps do this in different ways. The divide here is between electrically and petrol- or diesel-powered pumps and there are many subtypes within these two categories.  

    Water Pump Types 

    How They’re Powered 

    • Engine-driven 

    Pumps powered by petrol or diesel motors encompass the majority of water pumps used on large agricultural properties, construction sites, and mines. They’re also more common in domestic use. Engine-driven pumps can move large amounts of water, are simple in design, and are easy to use and maintain. They are restricted to outdoor use since they emit carbon monoxide. 

    • Electric  

    Electric water pumps run off power from the mains supply. They’re often not as powerful as engine-driven variants but commendably serve light to medium duty domestic use, particularly household water supply and draining of tanks and pools.  

    How They Operate 

    Based on how they move water, pumps can be categorised into two basic groups – centrifugal pumps and positive displacement pumps. Though they operate in different ways, the purpose is the same.

    – Centrifugal Pumps

    These have one or more shaft-driven impellers set inside a casing. The impeller is always submerged in water, and with the pump on, spins quickly. The rotation creates a centrifugal force, thrusting the water out of the casing and through a discharge port. The velocity of rotational spin of the impeller is converted to pressure energy or “head”. Additional water enters the pump through suction or inlet port. 

    – Positive Displacement Pumps

    These move water and liquids at a continuous flow rate. Water is repeatedly enclosed in the pump housing and moved mechanically. Lobes, gears, screws, or vanes are the pump elements that do this in a circular motion in rotary pumps, and diaphragms, pistons, or plungers in reciprocating positive displacement pumps. 
    Centrifugal pumps are better where a high flow rate is needed and constitute the majority of water pumps in use. Positive displacement pumps are for specialist applications requiring higher water pressure. 

    Water Pumps by Application

    Electric Water Pump
    Source: youtube.com

    Jet Pumps

    Jet pumps are a type of self-priming centrifugal pump. The pump compresses air to draw and move liquids, meaning it can be used above a body of water, like wells or flooded basements. The centrifugal force of the impeller creates a vacuum and a steady increase of water pressure at the head, so can be used at greater depths. Use a jet pump to bring potable water to taps, sinks, and showers from a well, for irrigation of farmland, to get water to sprinkler systems, and to remove unwanted water from any area. 

    Submersible Pumps

    A submersible or sump water pump is a type of centrifugal pump that can be fully submerged in water. As opposed to jet pumps that create a pull, the impellers in submersible pumps instead push water to a suitable location. The pressure from the existing water body in which it is submerged aid water movement, and also prevents cavitation or the formation of bubbles that can have a detrimental impact on parts. Submersible pumps are extensively used in drainage and wastewater applications, as well as irrigation and drawing water from deeper boreholes. They’re also the pumps you’d use in clearing floodwater. 

    Firefighting Pumps/Water Transfer Pumps

    Heavy-duty diesel firefighting pumps are designed to have high pressure to deliver bursts of water at further distances. There are both centrifugal and positive displacement variants, as well as portable pumps and those fitted in commercial and industrial buildings. Smaller and cheaper fire fighting pumps, running on petrol are also sold. Water transfer pumps are different in that they move large volumes of water but at lower pressures. Also called dewatering pumps, they allow for high water flow and are ideal for moving larger quantities of water, for instance in delivering water to larger acreages, or effectively clearing large areas after flooding. 

    Trash/Sludge Pumps

    These are more often of the positive displacement type, that besides water can also move the debris and solids in it. They’re used in mining for quickly transferring slurry and ores, in large-scale wastewater treatment, clearing construction sites, and in other industrial uses. Diesel and petrol variants are available. The specific application also means a higher price tag. 

    What to Look for in a Water Pump? 

    Water Pump taking out water
    Source: youtube.com

    Flow Rate and Inlet Size

    This is how quickly the pump moves a specified amount of water, in litres per minute (LPM). Smaller household pumps start with a flow rate of around 100 litres a minute, mid-range water transfer pumps hover around 500 litres a minute, and large, powerful industrial pumps are rated for 5000 litres a minute or more. The flow rate largely depends on the inlet size, where the pump draws in water. Pumps that need to move large quantities of water, like water transfer and sludge pumps will often have wider inlet valves. For instance, a pump with a 4″ inlet valve will move water four times faster than one with a 1″ inlet. 

    Max Head and Pressure

    Head refers to the maximum height the pump can pump to. This is important in submersible and jet pumps, as they are often used to pump water from bigger depths. Maximum head also matters in firefighting, for example in containing fires in taller buildings. Related to this is the pressure a pump can generate, specified in PSI. Transfer pumps, for example, operate under lower pressures as compared to firefighting pumps. 

    Type of Water 

    The quality of the water will determine what kind of pump you need. There’s a stark difference between trash pumps and water transfer pumps in the type of water they can move. Always regard the specifics of where and how the pump will be used. 
    Lastly, consider brands, build quality, and availability of attachments like hoses and spare parts. Budget will play a part, and go for a pump that you can afford, but also one which meets your needs.