Mech Eng students making a world of difference

Mechancial Engineering students Sam Stedman and Andrew Merson are both members of Engineers Without Borders who, thanks to alumni donations, the Douglas Bomford Trust and Departmental funding, had the chance to travel to Malawi last year to carry out their research.

Mech Eng student working with farmers in Malawi

The pair had been working on a pedal powered irrigation pump which they demonstrated to interested academics and technicians at the University of Mzuzu. The aim was to start a partnership with the Centre for Excellence in Water and Sanitation with future development of their pump in mind. The workshop raised some important issues and criticisms which provided them with some good ideas for improving their design and approach. After the workshop, they were invited to collaborate with the Department on a further research project.

The team began their design test work after being introduced to Mr Msiska, head of the Nkhata Bay District Agricultural Office, an arm of the Government that advises low-income farmers with the aim of providing food security and raising standards of living.

Mr Msiska proposed a pair of irrigation sites near Chandero village. The two sites are shared with around 30 families and have been used as a test bed for previous government farming trials.

They agreed to leave the pump with them for a few days before returning to receive feedback. One of the main points was that the farmers were disappointed with the low flow rate compared to the physical effort they were putting in.

Having recorded an output of 20l/minute during testing, Sam and Andrew were surprised to hear that the farmers were disappointed with the flow rate. However, they found that the cross-sectional area of the pipe was actually restricting the flow and by changing some of the pipe connections to ensure the flow was not travelling through any cross sections smaller than 3/4” and changing the outlet pipe to 1” internal diameter they were able to increase the flow rate by almost 20%.

When the pump broke during testing one of the farmers took a piece of rubber chord from the rack on his bike and tied it around the pump to hold it in position. Rubber chord is used by everyone to tie cargo to their bikes so Sam and Andrew decided to use it as a key part of their redesign, along with offcuts of timber, making the new design much simpler and intuitive to locals for ease of manufacture and repair.

“Getting this feedback from the villagers taught us never to make judgements based solely on an engineering principal - think logically and test your idea before adopting it or discarding another,” says Andrew, “and make sure you design with local skills and knowledge in mind. By observing how the farmers used our pump we were quickly able to see where the unnecessary complications were.”

After the field testing and improvements were complete, the team began interviewing farmers using a closed-answer survey in order to compare the new data to previous research in the area. In total 120 farmers at 9 irrigation schemes within the district and 2 senior government coordinators were interviewed.