What is a ram pump? How does it work?

The hydraulic ram pump, also known as a water hammer pump, is a unique type of cyclic water pump that utilizes hydropower to elevate water to a higher position. This pump operates without the need for an external power source, instead harnessing the kinetic energy of flowing water and the water hammer effect. The water hammer effect here refers to the pressure shock wave generated when flowing water is abruptly halted by the rapid closure of a valve.

At the heart of the hydraulic ram pump are two one-way valves: the waste valve and the delivery valve. The operation process of the pump typically includes the following steps:

1. Opening the Waste Valve: Initially, the waste valve is open, allowing water to flow through the inlet pipe (drive pipe) and out through the waste valve.
2. Acceleration of Water Flow and Closure of Waste Valve: As the water flow increases in speed, the flowing water eventually forces the waste valve to close. At this point, the water in the pipe stops moving, converting its kinetic energy into pressure energy.
3. Water Hammer Effect and Opening of Delivery Valve: The closure of the waste valve creates a water hammer effect, generating high pressure inside the pump. This pressure differential opens the delivery valve, forcing some of the water into the delivery pipe.
4. Cyclical Operation: As the water flow in the delivery pipe slows down and reverses, the delivery valve closes. Simultaneously, the pressure pulse from the water hammer effect travels back up the inlet pipe to the source, creating a suction pulse that reopens the waste valve, initiating the next cycle.

The pump also includes a pressure vessel containing air, which serves to cushion the hydraulic shock caused by the closure of the waste valve and improves the pump’s efficiency by allowing for a more constant flow through the delivery pipe.

The energy efficiency of a hydraulic ram pump is typically around 60%, but it can reach up to 80% under optimal conditions. The actual volume of water delivered will be reduced due to the energy efficiency factor. For instance, if the source is 2 meters above the ram and the water is elevated to 10 meters above the ram, only 20% of the supplied water can be utilized, with the remaining 80% being expelled through the waste valve.

The design of the drive pipe is crucial for the pump’s efficiency and reliable cycling. The drive pipe should have a constant diameter and material and be as straight as possible. Where bends are necessary, they should be smooth with a large diameter. While PVC pipes may work in some installations, steel pipes are generally preferred.

Hydraulic ram pumps are particularly useful in remote areas or situations where water needs to be pumped to a location higher than its source, as they require no external energy source other than the kinetic energy of flowing water​.