Simple, smart ideas go with the flow

Rodney Sharp with his self-powered water pump.

Dean Taylor looks at Kiwis' latest inventions, among them a system that allows farmers to irrigate land without waste

Hamiltonian Rodney Sharp and his wife Angela own a business called Progressive Group - and judging by their three grassroots innovations at Fieldays, the name is apt.

The show-stealer was their self-powered water pump, which works on the theory of differential area.

Sharp says it isn't rocket science. Then he explained it and it sounded a bit like rocket science.

It goes like this: a large area of water with a small pressure works on a small area of water, making large pressure.

It's a simple calculation -- halve the area, with the same force, double the pressure.

So with no electricity and just a 10m head of water, that same water can be pumped up to a 100m head.

Sharp says the benefits, apart from using no power, are the quiet efficiency of the system and low maintenance requirements.

The pump runs off low water flows between 10-50 litres per minute and runs so long as there is flow. When the flow stops, so does the pump.

When it starts again, the system auto bleeds and starts operating.

There is no accumulator or air tank needed, and no water hammer.

The parts are commercially available worldwide and the design is simple and robust.

The diaphragm is mounted externally so it is quick and easy to change if necessary.

A conventional ballcock can be used in the system to shut off the pump.

Sharp says it is ideally suited to any application where power isn't available -- generally remote locations where a slow but steady supply is all that is required.

Sharp says there was a lot of interest in the design at Fieldays and he has received more enquiries since.

He says each pump is fine-tuned to suit each application.

Sticking with water, Sharp also showed off his Tank Watcher -- a device that automatically turns off the outlet from a main tank if there is a leak or breakage.

Again, it doesn't require electricity and is simple.

The system utilises a smaller, intermediary tank to create differential flow, using a simple float and weight system.

If there is a leak or break to a pipe, fitting or trough, the outlet supply from the main tank is automatically shut off.

Sharp says a handful of units have been sold to date, and two have already worked to save precious water.