ABSTRACT
A centrifugal pump is a mechanical device designed to move a fluid by means of the transfer of rotational energy from one or more driven rotors, called impellers. Fluid enters the rapidly rotating impeller along its axis and is cast out by centrifugal force along its circumference through the impellers vane tips. The action of the impeller increases the fluids velocity and pressure and also directs it towards the pump outlet. The impeller, on the opposite side to the eye, is connected through a drive shaft to a motor and rotated at high speed. The rotational motion of the impeller accelerates the fluid out through the impeller vanes into the pump casing. The general term pump is used to describe the mechanical device which transfers energy to the fluid to cause the increase in pressure and flow rate seen when a pump is used, there are actually many types of pump available to be used, so it is essential the correct one is selected for the application which is being designed. When a casing contains only one revolving impeller, it is called a single-stage pump. When a casing contains two or more revolving impellers, it is called a double or multi stage pump. Previously manufactured pumps are of the involute casing type and most often times are imported. It is the desire of the authors to design and manufacture a centrifugal pump with circular casing using locally available materials and see how it compares to the imported centrifugal pump with an involute casing. The aim of this project is to design and manufacture a centrifugal pump with a circular casing.
The centrifugal pump was designed and manufactured using appropriate materials from locally available materials. The material used was Aluminum scrap. It was first taking to foundry shop where it was melted and casted into the desired shapes. Pattern was first made. We made use of a master pattern which was lagged using rubber tiles to increase the thickness. We used green sand to prepare the mould where it was mixed with a bit of water. The aluminum scrap was placed in a graphite crucible and placed in a furnace where it was heated to a melting point of 650 C. It was then poured in moulds and allowed to solidify. The casted pump parts was then taking to a machining shop where it was machined to the desired shapes
The pump performance was evaluated in the department of production workshop. The test was effected by using water filled in measured containers, the time taken to empty each measured quantity is noted against the Head of water pumped. The water rose to a height of 34.7m and the discharge recorded was 16,200 liters/h i.e. 4.5 liters/sec.
The pump was designed to deliver 5 liters/sec at a height of 40m therefore the achieved performance of 90% efficiency, is satisfactory and acceptable for a centrifugal pump that falls within this category of specific speed.
