Consumer Association Testing of the Rower Pump
This page summarises the Consumer Association tests of the original Bangladesh Rower Pump. SWS Rower Pumps incorporate several improvements but are based on the same principles.
The Rower is a high-capacity low-lift pump designed primarily for irrigation. The operator pulls directly on the plunger rod by means of a T-bar handle, and the angle is convenient for operation from a sitting position or standing using a rowing action. The cylinder is a PVC tube with heat-swaged ends and the aluminium piston is fitted with a leather cup washer and flap valves cut from tyre inner tubes. Several different sizes are available.
The pump is fitted with a surge chamber, and is normally embedded in earth for support and protection, or may be supported by a smaller earth bank and protected by strips of bamboo around the cylinder.
The pump was designed for manufacture in a developing country and most components are easy to make. Some skill is required in heat-forming the PVC tube and spinning the surge chamber, and care is needed in machining.
Installation of the Rower pump should be very easy, particularly if plastic pipe is used. The most important tool may well be a spade or shovel to construct the earth bank. Care is needed to achieve airtight joints in the drop pipe, as any leaks will affect the efficiency of the pump.
Maintenance is very straightforward and requires only the simplest hand tools. The Rower is a true VLOM (Village Level of Operation and Maintenance) pump, though the need for priming introduces a pollution risk when it is used for drinking water. The pump achieves a high delivery on each stroke, and its discharge of 27 litres per minute at 15 cycles per minute is also high.
The 4000 hour endurance test was carried out at 19 cycles per minute and a head of 7 metres. No breakdowns occurred, though the check valve was replaced after 1000 hours as inspection revealed that the rubber flap valve was loose. Some joints in the drop pipe were found to be
leaking during the test, and the threaded joints were replaced with cement joints. As well as reducing performance, leaking joints caused a rapid loss of prime.
Small amounts of surface rust were found on the check valve and plunger body fixings and there was slight pitting of the plunger rod, but all parts remained serviceable. The cylinder bore was worn at the end of the test, resulting in a 2mm step in the bore at the end of the swept stroke.
The volume delivered per stroke was down on the original performance test, but still well over one litre.
User reaction was generally favourable, once users were instructed in the appropriate method of operation. Only small children found the pump difficult to use. Everyone liked the very high discharge, though some objected to getting wet when water spurted out of the pump at the start of the return stroke. The lack of an upper stop caused some problems, with some stronger users pulling the plunger right out of the cylinder.
The impact test was not applied, as the Rower is intended to be protected against such eventualities. The handle can be distorted quite easily, but is equally easy to straighten.
The overall conclusion of the laboratory trials was that the Rower is a commendably simple pump, easy to install, maintain and repair. Its main application is likely to be low-lift irrigation. Performance falls off with time, because of wear, but all wearing parts are cheap and easy to replace.
Performance data (typical values)- 54mm cylinder
The volume discharged per stroke was about 1.8 litres.
|Head (meters) || 7
|Pumping rate (cycles/min) || 15
|Volume/minute (litres) || 27
|input(watts) || 48
|Efficiency (%) || 64
|Maximum handle force (kgf) ||20
|Leakage of foot valve (ml/min)|| High
The Rower pump ratings are based on performance in the laboratory tests and on experience
and judgement of Project staff. The Rower was developed principally as an irrigation pump, and
produces a high discharge. As a suction pump, it is not suitable for pumping lifts in excess of
7 metres. It also requires priming and is therefore at risk of contamination if polluted water is
used for this purpose.
The Discharge Rate of 27 litres per minute at a pumping rate of 15 cycles per minute declines as wear takes place in the PVC cylinder, but remains high enough to justify the pumps "good".
Ease of Maintenance. Practically no tools are needed for maintenance and the pump earns a good rating.
Reliability. The reliability rating is also good, for outputs up to 4m3/day, as the repairs which are necessary can be carried out very quickly and easily. The rating drops to 'adequate' when daily output rises to 8m3/day.
Corrosion Resistance. Though small amounts of corrosion have been detected both in the laboratory and in the field in Bangladesh, they have not been extensive enough to impair the pump's performance, and should not be a problem unless the groundwater is highly corrosive.
Abrasion Resistance. The Rower design allows it to pump sand-laden water without difficulty, but the wear of the cylinder walls will be accelerated if sand is present regularly.
Manufacturing Needs. The Rower has been designed for cheap and simple manufacture in a developing country with a low industrial base.