Stichting Connect International

Verklaring bij de tekening van de RAM pomp
A - RAM pump
B - Drive Pipe
C - Catchpit
D - Supply Pipe
E - Head Water Level
F - Working Fall
G - Waste Drain
H - Delivery Main (going towards a water tank up hill)
I - Inlet Valve and Strainer

The picture shows a RAM pump that is used in hydram schemes. Water, entering the steel drive pipe flows through it by gravitation until it reaches the RAM, passes through the RAM and out through the pulse valve into the waste drain. As the water flows, its velocity increases until the pulse valve is no longer able to pass the volume of water flowing: at this point the pulse value is suddenly closed. The outlet thus being closed, the flow of water suddenly stops. This produces a concussion of more or less severity in the body of RAM according to the height and distance from which the water is flowing. The result of this concussion is that a portion of the water in the body of the RAM is forced upwards through the delivery valve into the air cylinder. At the same time the recoil allows the pulse valve to return to its original position. The outlet being thus reopened, the water which was brought to rest by the closing of the pulse valve recommences to flow through the RAM until it acquires the necessary velocity to raise the pulse valve a second time, closing the outlet, producing a concussion and forcing more water into the air chamber through the delivery valve. The water, which is forced into the air chamber, finds its way through a pipe, known as the 'rising main', to the place where it is required for use with a continuous flow being maintained so long as the RAM remains working. This series of events, which takes time to describe clearly, occurs from 40 to 90 times per minute, according to the size of the hydraulic RAM, the fall of the water driving the RAM, etc. The RAM will continue working automatically, the pulse valve rubber and delivery valve rubber being the only moving parts. The fall of water necessary to work a RAM may be as low as 0,5 m and with such a fall, water may be raised to 18 m. With higher falls, such as from 2 to 7 m and over, water can be raised to upwards of 100 m or more in height and 5 km in distance. Due to the action of the RAM, unless the conditions are unusually severe, and provided the RAM is kept working, it will be unaffected by changes in temperature especially low temperatures which might cause a conventional system to 'freeze up' unless some form of heat is provided.
A very positive aspect of RAM pumps is that they need very little maintenance (only the replacement of a rubber ring once every year or so) and have a lifespan that can be more than 100 years!