Since the very earliest history, people have been using devices for moving water. Efficiently pulling water out of wells has been a problem since agriculture was invented.
The first devices for doing that were precursors to the pump. In about 2000 BCE, the Egyptians went one step beyond the suspension of a bucket on a rope. The shadoof incorporated leverage by hanging the bucket on the long end of a rod with a weight on the other end. Eighteen centuries later, in 200 BCE, the Greeks used a rotating device (a circular inclined plane) to raise water. The device was a large screw--water was raised out of a well or a stream by essentially screwing through it. In the 16th century, devices were lifted water from a source using a series of buckets on a wheel powered by stream currents.
Scientific principles of flow dynamics and water pressure were first explored by scientists in the 18th century. These studies enabled inventors to design more modern pumps. The first of what we would call true pumps was invented in the 17th century. These used pistons to create partial vacuums and air pressure to draw amounts of fluid into a tank then eject the water into target containers. In the 18th and 19th century, the industrial revolution in England and Europe was powered by steam-powered pistons and pumps.
The modern water pump is perhaps best exemplified by the kind of lever-activated pump used to draw water out of deep wells in the early 20th century. These pumps use a system of valves and levers. A cylinder leads from the pump deep into the well. When the big activation lever is pulled down by the person operating the pump, a lower valve closes, trapping water in the cylinder and a top valve opens admitting air which pushes the water in the cylinder higher. The water in the cylinder rises with every lever stroke until the water eventually reaches the spout and pours out.
The electric pump uses motors to move the water continuously. Two major types of electric pumps, centrifugal and positive displacement pumps, are used in industry today. Both types are capable of moving a steady stream of liquid. Both kinds of pumps can be used immersed in the liquid they are pumping--for example to displace sea water or raise oil.
The centrifugal pump uses a revolving impeller (or fan-like device) to mechanically move the liquid into the spout. Moving the water lowers the water pressure at the intake side which draws water into the pump. The impeller is driven by a motor at high-speed inside a casing, typically 1,750 rotations per minute (RPM) or 3,500 RPM. Liquid enters the center of the casing and is pushed by the impeller to the outer edge of the casing where it exits through a discharge port. These rapidly revolving centrifugal pumps are used in industry or emergency services because they can generate very high flow rates. They are subject to a lot of wear, however. The impeller regularly has to be replaced. They are designed for low viscosity liquids that can be carried more easily by the impeller. They become very inefficient with high viscosity liquids.
Positive displacement pumps. The old-fashioned hand pump is a simple example of a positive displacement pump. These pumps trap a finite parcel of water into a container then mechanically force the trapped volume into the discharge pipe. The positive displacement principle will operate at the same rate regardless of the fluid pressure on the inlet end. Centrifugal pumps will not. Positive displacement pumps also work better with viscous liquids like oil.
Mader Electric offers a full line of industrial pumps including extremely durable submersible pumps, high-efficiency pumps, and well pumps. These pumps are used in HVAC systems, to boost water pressure, and in sump pumping and sewage pumping. Submersible pumps are used to draw well water, for agriculture, as well as water removal in cases of flood or water control.