Double diaphragm pumps use the same 'enlarge/compress' process as single diaphragm pumps, but by running two diaphragms in parallel they offer a far more energy-efficient pumping solution.
By connecting two diaphragms together, they make use of the expansion of one diaphragm to aid the contraction of the other and vice versa, pumping twice as much fluid in the same time and using a lot less energy in the process.
To see an air-operated pump in operation, look at the movie below:
As you can see from the movie, air is pumped into the central valve chamber which forces the diaphramps to expand and contract and this motion serves to force fluid into the pump and out again.
In this way, a double diaphragm pump can move a huge amount of fluid at high speed - in the case of a Husky 2150 air-operated diaphragm pump up to 150 gallons per minute (568 litres per minute) can be pumped at a fluid pressure of up to 120psi (8.4 bar, 0.84 MPa)
The marvellous thing about double diaphragm pumps is you don't have to be especially skilled to use them. If you can use a vacuum cleaner around your home, you can learn to use a double diaphragm pump too!
This is because double diaphragm pumps are very safe to use - they are a standard feature on oil rigs and oil tankers around the world as well as other safety critical sectors such as the motor manufacturing and chemical industries
Double diaphragm pumps are self-priming, which means they can be run dry for a short time when no material is available for pumping - compare this to an electric pump which would soon burn out when there is nothing for them to pump.