In 1996, English engineer, Frederick Philip Selwyn, patented a ‘fluid pressure amplifier’ which revolutionised ram pump technology with a new venturi effect valve for the Zero Energy Papa Pump.
This Venturi Valve uses the low pressure generated by high velocity water flow around a curve-shaped elastomeric valve (with low pressure loss) enabling rapid closure and with a relatively small cross sectional area and low weight. The Venturi Valve is configured as a ring section positioned around the supply inlet of the pump with the delivery outlet of the pump being directly in line. This allows the pump structure to be concentric and therefore inherently strong. Upon closure of the valve, it permits efficient water delivery by acting in line with the supply via a second smaller venturi effect delivery non return valve. The elastomeric material and operation of these valves also allows them to self-return without weight or spring assistance.
This unique technology and design dramatically reduced the weight, manufacturing cost and number of components required - as well as providing an overall improvement in efficiency.
Inside the Papa Ram Pump
Water enters the ram pump through the supply port and flows around the main valve to the exhaust port.
As the flow increases around the main valve, a differential pressure occurs causing the valve to suddenly close. The flow and mass of water is then directed through the non-return valve into the delivery port at a higher pulsed pressure.
This pressure suddenly reduces causing the main valve to reopen and the cycle repeats.
Turning the adjuster to open
the valve allows flow through
the pump to be regulated so
that a greater flow generates a
greater pressure and water delivery.
Animation of the Pumping Cycle
Papa ram pump
Water Delivery Principles
For your zero energy Papa Pump site to be viable you must have...
A spring, stream or river with a flow of at least 50 litres per minute
and the watercourse must fall to give you a Supply Head of a least 1 metre.
The Supply Head is the difference between the highest point of your watercourse and the lowest point across your land
The greater the Supply Head, the greater the amount of water you can deliver
and the higher you can potentially lift the water.
The main objectives to planning an efficient system is to maximise the Supply Head but to keep the Supply Pipe (between the Supply Tank and the Pump) as short as possible. You can achieve this by running the Feed Pipe (between the Catchment and the Supply Tank) along the contours of the land as shown below.