How does a hand pump work?

Hand pumps may be the most underrated hero to accelerate the rural economy. Here's how they work

The most common tool to access a life source like water — this innovation boasts of none of the accolades that modern machines enjoy. Yet the simplicity and efficiency of design drives a sea of devices that permeate our lives at home and in industries.

The unsung hero that India should be particularly proud of is called India Mark II. A human-powered pump designed to lift water from a depth of 50 m or less, it is the world’s most widely used water hand pump. It was designed in 1970 through the joint efforts of the government of India, UNICEF and WHO. Its purpose was to address the deathly problem of paucity of water and draught in rural areas of developing nations. By the mid 1990s, five million of the pumps had been manufactured and installed around the world.
To read more about how hand pumps revolutionalised rural life, read.
What does it do?
Simply defined, hand pumps are manually operated pumps that use human power and mechanical advantage to move fluids or air from one place to another.

The water pump is operated under the principle of pressure theory. There are two plungers, one is top side and other is bottom side and which is sealed by valve. When with hand pressure, top plunger will rise above and take some water but bottom plunger which is sealed by tight valve, will not send it again to wall. So, water will reach outside and after this we can use this water.
There’s a crucial supporting actor here, a check valve is a type of valve that allows fluids to flow in one direction but closes automatically to prevent flow in the opposite direction (backflow).
Where do you find check valves?
Heart valves are essentially inlet and outlet check valves for the heart ventricles, since the ventricles act as pumps. They are also present in domestic devices and industrial machines.


How a hand pump works
For a pump to work, you need a hose to come out of where your water is (which is attached to the INLET) and a hose to where it’s going (which is attached to the OUTLET). Between the two is some way to move the water. Moving water’s easy but if you want to do it super-simple, you need to use a pump kind of like a bicycle tire pump. Those pumps just go up and down. If you don’t have a way to allow water to come in one way and out the other, you’ll just be pumping water in and pushing it right back out where it came from.

There are only three components that make up a hand pump: the piston, the inlet check valve, and the outlet check valve. The key is how to make each of them. You need water to flow in one direction and not the other. A check valve is designed to do just that.
One check valve is in the hose from your water source to your pump. It lets water be sucked through the hose to your pump but when you push it back out, it clogs up and doesn’t let it go back through.
The other check valve goes from your pump to wherever you’re trying to put your water. It allows you to push water out of your pump but doesn’t allow it to be sucked back in when you pull up on the lever.

If you’d like to build a hand pump at home, here’s an easy tutorial we found;


Photo credit: Julia Maudlin

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