Evans Water Engineers

EVANS ENGINEERING

TRECARRELL MILL · TREBULLETT · LAUNCESTON · CORNWALL · UK · PL15 9QE
+44 1566 782285 · www.evans-engineering.co.uk · email sales@evans-engineering.co.uk

Pumps and Pumping Systems

 

Although the family started in the pump business and became a world leader in areas such as steam driven tar and sinking pumps, today we are involved with innovative and bespoke equipment. Those that come close to our hydro business are very low lift and high volume.

Low cost low lift axial-flow pumps are designed for applications, which include tank transfer, flood control and irrigation schemes. Simple and robust construction derived from our experience of low head water-turbines, means that the units can be virtually maintenance free. The range extends up to runner diameters of 1200 mm with several layout options and materials including stainless steel and cast aluminum. Consideration should be given to the maximum flood levels, grit and trash as well as the method of installation and maintenance. Drives may be electric, diesel or wind power.

The maximum lift is about ten times the runner diameter per stage and three stages are feasible. The water lubricated steady bearings are fully adjustable so that wear can be taken up, rather than replacing bearing sleeves as soon as there is appreciable lateral movement. Special coatings can be applied to the runner and guide vanes if abrasive sand is present. Packaged flumes and screens can be supplied for the inlet and outlets sides, for temporary installations on riverbanks. Siphon breakers or reflux valves are incorporated as the installation dictates.

The ‘Elboflow’ layout is suitable for vertical lifts or angled up river or canal banks. It lends itself to a packaged approach for rapid installation but protection of the inlet and the supporting structures are important considerations. Small units can be pivoted to facilitate maintenance.

The ‘Uniflow’ layout of open flume pump is more suited to very low lifts, which may be little more than one runner diameter. The working parts can be withdrawn from the flume side so that the main flanges do not have to be broken.

The ‘Fixed’ layout is the lowest machinery cost option, but requires the construction of a concrete flume. It is suitable for applications where the lift is less than five metres and where access is difficult or lifting equipment is not available. Aluminium castings may also be appropriate in these situations.

Large capacity diaphragm pumps are under development for handling slurry, mine-tailings and storm water. Objects as large as 300 mm will be able to pass through without any difficulty. Enquiries from potential users are invited to make contact with us giving their specific requirements.

Water driven water pumps powered by waterwheels, or in the form of ‘Hydraulic Rams’, were manufactured by Joseph Evans for well over a hundred years. Although there is considerable interest in these systems, the field experience is far from satisfactory. The ‘Hydraulic Ram’ though simple to manufacture, has several weaknesses. It is not obvious to the layman how they work, so if they stop due to wear or blockage, they may not get repaired. More complex but visually understandable systems have been more successful and although he manufacture of a ram is simple, the quality of the few components must be good. Installation of a ram has to be right so that there are no significant change to the delivery pressure caused be taps too close to the outlet, which may cause the ram to stop.