Design of automatic water tank filling system using a programmable logic controller

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August 2016
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The drinking water purification industry has become one of the largest industries in Ghana. A search conducted on the National Association of Sachet and Packaged Water Producers (NASPWAP) suggests that there are about 6,000 of such companies registered in Ghana in the last five years. Currently a lot of water purification systems in Ghana are either manual or semi-automated with the former in the majority. In the absence of automation, plant operators have to physically monitor performance values of water and equipment to determine the best settings on which to run the production equipment. Some of the automated systems in use employ relay logic associated with large amounts of electrical wiring. Manualization of a water purification processes exposes the process to some shortcomings or challenges. In a water purification unit such as Everpure Ghana Limited, there are about 250 water tanks and 100 manually operated valves or units to control so monitoring is difficult and presents many challenges. This industrial project was aimed at designing an automated system of water tank filling using a programmable logic controller. The design was supposed to have the advantage of reducing human contact with the system and ensuring its efficiency. The method used in this project describes the main components used in the system design such as liquid level sensors, pump, and solenoid valves. The flow rate (using existing data from Everpure Ghana Limited), operating pressure and system head were calculated to select the right components for the system. The ladder logic for the water tank filling system was implemented by simulation using a Programmable Logic Controller (PLC). Picosoft 6 simulation software was used to demonstrate the automation at tank filling and tank emptying in relation to the valve opening and closing. To justify the benefits that can be accrued from automating the tank filling system, cost reduction and time savings analysis were calculated. Less human contact means less cost in terms of labour, maintenance, utility bills waste. The system provides room for improvements, so sensors and pumps can be increased as well as enhancing the protection of the pump.
An industrial project report submitted to the Department of Mechanical Engineering, College of Engineering in partial fulfilment of the requirements for the degree of Master of Engineering (Industrial Operations with Management).