ABSTRACT

Pressure losses generated through elevated water storage tanks in various high-rise buildings have become a great concern, losses and other plight experienced in homes and industries where elevated tanks are used as means of water storage and distribution can be associated to design factors or considerations not fully satisfied. To properly address these issues and challenges, a modernized method of pressurizing water in a distribution system was introduced, a Hydro-pneumatic pressure booster tank system is a system that utilizes air in its operation to boost water pressure and give enhanced water outlet pressure. However, it is recommended that a Hydro-pneumatic water pressure booster tank system is designed using appropriate design codes and standard, appropriate material selection and stress analysis performed to ascertain the strength and reliability of the tank against failure. This project therefore presents the design of a 1800 litres Hydro-pneumatic pressure booster tank that can safely boost water pressure up to a maximum allowable pressure of 9 bar using Fupre hostel as case study. The required pump capacity, pipe size and velocity, total tank volume was calculated in accordance to AWWA standard, the pressure tank shell thickness, head thickness and flange rating was designed in consonance with the requirement of ASME and API 650. Excel table format was used to perform design calculations, Design specification and Bill of Materials. SolidWorks was used to perform static structural analysis of the pressure tank to ascertain its integrity against catastrophic failure. CAD drawing of the designed hydro-pneumatic tank and a model were presented for this project. The results obtained from the Stress analysis of the hydro-pneumatic tank shows that the tank will function safely when operated at the maximum calculated internal pressure of 130.7psi (9bar) since the deformation of the tank was within the elastic range which is below the Yield strength of the selected design material.

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CHAPTER ONE

1.0 INTRODUCTION

1.1 BACKGROUND OF THE STUDY

Although elevated water tank system for water storage and distribution under pressure, has been in existence since ancient times. Rober (1965). This system of storage employs the use of elevated platforms. The storage tank is placed on a platform elevated to a height sufficient to pressurize the discharge of water through gravity. These elevated platforms may be constructed of wood, concrete or metal (steel), with steel being the most common material for elevated platform construction, as stated by (Dolor, 2014). The different types of water distribution and storage systems designed to meet different needs for industrial and domestic purpose, these systems can be easily differentiated by their physical features like component configuration, type of material used in the construction, and also by the mode of  water distribution: by gravity pressure system, direct pressure system or by pneumatic pressure system. 

Pneumatic water pressure booster tank system of water distribution is a modernization of the older gravity tank method used in elevated storage tank systems. Its main purpose is to control or boost a limited water supply pressure to a higher or more uniform value so that a continuous and satisfactory water supply will be available at all plumbing fixtures within the system. The fundamentals of a system which accomplishes this purpose consists of a suitable booster pump, a hydro-pneumatic bladder tank and essential control devices such as a pressure switch, pressure gauge, foot valve and a non-return valve, to aid an automatic operation of the system with the least amount of supervision. The pump is used for supplying the required amount of water into the tank at the proper pressure while the tank acts as a storage vessel for the proper ratios of water and air within the pressure and levels maintained by the pressure switch. Pneumatic pressure booster tanks are widely used to enhance water flow rate, serve as a pressurized water storage tank for industrial and domestic purpose and also help to maintain the pumping-cycle rate required to avoid overheating and premature motor failure of the booster pump motor. These pressure tanks are usually above ground level with supports to hold its weight. Water pressure boosting systems are important facilities in high rise buildings. There are different types of water pressure tanks designed to meet different water pressure enhancement needs. These tanks can be easily differentiated by their physical features like body shell configuration and stance position if it is either horizontally or vertically positioned. They can also be differentiated by the water storage mechanism in the tank which could be either a diaphragm mechanism or a bladder mechanism. In pressure vessel designs these mechanisms are not used. Air and water are in direct contact.

Hydro pneumatic pressure tanks are constructed of metal (steel) owing to their use. They are designed to various capacities using codes and standards with an appropriate design method to produce a safe and reliable design.

1.2 STATEMENT OF THE PROBLEM

On observing water supply systems in FUPRE hostel equipped with elevated storage tanks, it was observed that water pressure developed in pipes through gravitational fall in the elevated tank fluctuates as a result of friction head loss through the pipe line, valves and fittings. Also as a result of many plumbing fixture connected to the water supply line, the distance of flow of water through pipes to all fixtures in the hostel. Therefore, this project focuses on the indigenous design and fabrication of a pneumatic water pressure booster tank system to enhance water supply pressure.

1.3 AIM AND OBJECTIVES OF THE PROJECT

1.3.1 PROJECT AIM

The aim of this project is to design and construct a pneumatic water pressure booster tank to maintain water supply in Fupre hostel within a selected pressure range of 3.5-6.5Bar.

1.3.2 PROJECT OBJECTIVES

Objectives of carrying out this project include:

1.    To conduct a survey on Pneumatic water pressure booster tank systems.

2.    To design a pneumatic water pressure booster tank using CAD software: SolidWorks 2014.

3.    To determine the actual stress distributions in the different locations on the pressure booster tank and the actual behaviour of the booster tank using Finite Element

4.    To construct a scaled-down model of the Pneumatic pressure booster tank system.

1.4 SIGNIFICANCE OF THE PROJECT

The need for accurate design and analysis of indigenous pneumatic water pressure boosting tank system is overwhelming, thus the information generated by this project would assist plumbing engineers to carry out better decision making and evaluation when considering the installation of water supply systems in domestic, commercial, processing and manufacturing industries.

1.5 THE SCOPE OF THE RESEARCH

This work will be delimited to the design, construction and testing of a pneumatic water pressure booster tank system of 1800 litres capacity, using FUPRE hostel as case study. A scaled-down model of the pneumatic water pressure booster tank system will also be constructed.