pump water without electricity or fuel
Principle of Operation
A hydraulic ram It harnesses the force of the water hammer, the so-called ram, to lift a fraction of the total water used to power the pump above its very origin. It is commonly used in remote areas with access to water level differentials, since it requires no outside source of power other than the kinetic energy of falling water.
History
The first ram pump was invented in 1796 by the Frenchman Joseph Michel Montgolfier for the purpose of raising water in his paper mill at Voiron. His friend Matthew Boulton took out a British patent on his behalf in 1797. The sons of Montgolfier obtained an English patent for an improved version in 1816.
Construction and principle of operation
A hydraulic ram has only two moving parts: a weight loaded "waste" valve, sometimes known as the "clack" valve and a "delivery" check valve, which makes it easy to maintain and is very reliable. Other non-moving parts are a drive pipe (PL) supplying water from a slightly elevated source and a delivery pipe (DPL), taking a portion of the water that comes through the drive pipe to an elevation higher than the source.
Sequence of operation
Hydraulic ram: 1. Inlet - drive pipe; (PL) 2. Free flow at waste valve; 3. Outlet - delivery pipe; (DPL) 4. Waste valve; 5. Delivery check valve; 6. Pressure vessel
At the beginning of the cycle, the waste valve (4) is open and the delivery valve (5) is closed. The water in the drive pipe (1) starts to flow by gravitational force, picks up speed and kinetic energy until it forces the waste valve closed. The momentum of the water flow in the drive pipe (1) against the presently closed waste valve (4) creates a so-called water hammer, raises the pressure inside the drive pipe (1) and thus opens the delivery check valve (5). This allows a proportion of the water under pressure to escape into the delivery pipe (3). Since this water is being forced through the delivery pipe (3) against gravity, its flow slows down and finally reverses, closing the delivery check valve (5) closes. If all water flow has stopped, the pressure inside the drive pipe (1) equals ambient pressure, which makes the waste valve (4) reopen to allow the above cycle to start anew.
When commencing operation for the first time, or after long periods of inactivity, the pressure vessel (6) contains air, only. The latter cushions the sudden build-up of pressure, when the waste valve (4) shuts close, and improves efficiency by allowing a more constant flow through the delivery pipe (3). Although the pump could work without any pressure vessel (6), its efficiency would drop drastically and the pump structure would be subject to extraordinary stress that shortens its life considerably. As the air in the pressure vessel (6) is under pressure, it tends to disappear gradually.
The optimum length of the drive pipe (1) is 5 to 12 times the vertical distance between the source and the pump, or 500 to 1000 times the diameter of the delivery pipe, whichever is less. With this parameters, pump cycles typically last 1 to 2 seconds. Typical pumping efficiency is 60%, but up to 80% are achievable. In order to optimise efficiency, the drive pipe (1) should be made of non-elastic, strong and rigid material.