ABSTRACT
This research is focused on the design of water supply (cold and hot) system of a three bedroom bungalow with adequate pressure. Polypropylene (PP) pipes imported from Italy and polyvinyl chloride (PVC) pipes made in Nigeria, the two most common plastic materials used for potable water supply lines were selected for the analysis and compared to find out which of them is more cost effective, provide better form fitting and higher life expectancy. The adequate flow pressure required for both pipes was found to be 20 Pa while the standard pipe size for the supply of both cold and hot water was found to be 19 mm. The average diameter of branched pipes supplying water to the three bedroom bungalow was 13 mm. For cold water supply, pipes number „1‟ and „2‟ had 34 loading units while pipes 3, 4, 5, 6 and 7 had respectively 3.5, 6.5, 4.0, 6.5 and 13.5 loading units (LU). The loading units for hot water supply to the building for pipes number „20‟, „21‟, „22‟ and „23‟ were respectively 4.5, 4.0, 4.5 and 11.5 LU. Pipes made of PP, though more expensive, are more durable and have higher life expectancy than the PVS ones, and are resistant to weather factors such as temperature and humidity. PP pipes are recommended to be used to run both cold and hot water supply to the building, while PVC pipes can be used to run only cold water supply to the building since they can be easily damaged.
TABLE OF CONTENTS
Title Page i
Declaration ii
Certification iii
Dedication iv
Acknowledgements v
Abstract vi
Table of Contents vii
List of Figures x
List of Tables xi
List of Plates xii
Appendix xiii
Nomenclature xiv
CHAPTER ONE
1.0 INTRODUCTION 1
1.1 General Background 1
1.2 Statement of the Problem 2
1.3 The present Work 3
1.4 Aim and Objectives 3
1.5 Significance of the Research 4
1.6 Scope of the Work 4
1.7 Definition of Operational Terms 4
CHAPTER TWO
2.0 LITERATURE REVIEW 7
2.1 Introduction 7
2.2 Water use in Residential Buildings 7
2.3 Residential Water System sizing 8
2.4 Distribution Systems 8
2.5 Water supply for Multi-storey Buildings 12
2.6 Water Storage Vessels 14
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2.6.1 Requirements relating to installation and water storage tanks 15
2.6.2 Requirements relating to access to water storage tanks 16
2.6.3 Requirements relating to materials used in water storage tanks 16
2.7 Water Source 17
2.8 Treatment Facilities 17
2.9 Storage Systems 18
2.10 Fire Protection 19
2.11 Water Pressure 19
2.12 System Layout 20
2.13 Common Pipe Materials 21
2.13.1 Copper Pipes 21
2.14 Internal Piping System Fusion 22
2.15 Physical Properties required for Pipe Materials 24
2.16 Fittings 25
2.17 Fusion Device 25
2.18 Total Dynamic Head 25
2.7 Review of Related Past Works 26
2.8 Research Gap 28
CHAPTER THREE
3.0 MATERIALS AND METHODS 29
3.1 Materials 29
3.2 Design Considerations 29
3.2.1 Materials Selection 29
3.2.2 Cost 30
3.2.3 Estimating Water Demands 30
3.2.4 Water Distribution System 30
3.2.5 Adequate Pressure 30
3.3 Plan Layout of the Bungalow and Description 31
3.4 Design Analysis of the water supply System 32
3.4.1 Pipe Size Analysis 32
3.4.2 Cold water supply calculation s 32
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3.4.3 Hot water supply calculations 50
CHAPTER FOUR
4.0 RESULTS AND DISCUSSION 56
4.1 Results 56
4.2 Discussion of Results 59
4.3 Cost Analysis 60
4.4 Polypropylene versus Polyvinyl chloride pipes 61
CHAPTER FIVE
5.0 CONCLUSION AND RECOMMENDATION 62
5.1 Conclusion 62
5.2 Recommendation 62
REFERENCES 63
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CHAPTER ONE
INTRODUCTION
1.1 Background of the Study
Plumbing engineering responsibilities overlaps into the professional areas of civil engineering, mechanical engineering, chemical engineering and process engineering. Traditionally, the plumbing Engineering performs the calculations, size the equipment and prepare the pluming design and construction documents under the supervision of a licensed mechanical, fire protection or professional engineer (Ho, 2010). In most states the mechanical engineer supervises the plumbing engineer‟s responsibilities in the following areas: Design of process and fluid flow process; design of plumbing systems and design of heat energy transfer.
A water supply system uses a combination of pipes (of different dimensions and materials), valves and outlets to deliver to the building users. Some water supply systems also use storage tanks and pumps. Designing a water supply system involves getting all of these elements right so that clean water is delivered to the user at the appropriate rate and temperature.
The design and calculations of water supply (hot and cold), drainage systems is important in the modern day building since most buildings now have central heating systems and pipes are conduit in building. In order to have a constant flow rate and avoid blockage of drainage pipes, calculations have to be done to get the required pipe size and fittings to use.
In the water distribution network and pipe sizing, allowance for pressure losses due to frictional resistance set in by fittings such as elbows, tees, bonds, taps and valves must be added to the actual length of the pipe (Bratsch-Blundel, 2008).
In the drainage system for a building, the drains from the plumbing fixtures are connected to vertical drain stacks that convey the waste and sewage to below the lowest floor of the
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building. The fixture drain traps must be vented to prevent their water trap seal from being siphoned by negative pressure or blown out by positive pressure in the drain piping. The fixture vent pipes must extend through the roof to outdoors. They can be run individually or be combined into one or more vents through the roof. This relieves and equalizes the pressure in the drainage stack to maintain the water seal in traps serving plumbing fixtures (Hongo et al., 2007).
Wherever possible, the sanitary drainage system from a building should discharge to the public sewer by gravity. All plumbing fixtures located below ground level should be pumped into the public sewer or the drainage system leading to the sewer. The pump line should be as short as possible and looped up to a point not less than 0.6 meters (24 inches) above ground level to prevent back siphonage of sewage. The pump discharge rate should be controlled so as not to cause scouring of the internal bore of the pump line or the drainage or sewer system into which it discharges. High-velocity discharge rates may also cause the flooding of adjoining plumbing fixtures or overloading of the sewer itself. The sump pits for sewage pumps must have sealed covers, be vented to outdoors and have automatic level controls and alarms. Sewage pumps in a building should be duplex, with each pump having 100 % of the required pumping capacity for the building. Alternatively, an approved vacuum drainage system may be considered (Belobratova, 2011; Hongo et al., 2007).
1.2 Statement of the Problem
Required pressure has been a major challenge in getting water to all the appliances in any facility since it is not possible that all the appliances are in use at the same time. Therefore, for economic reasons the scheme provide for a peak usage which is less than maximum demand (Ladd, 2005). With this method a unit rating is devised for each type of sanitary appliance based on its rate of water delivery. If water pressure is too low, this will be inconvenient for the
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building users. And if the pressure is too high, this will lead to wastage of water as well as high wear and tear on the system (Säärekõnno and Suurkask, 2007; Ladd, 2005).Pressure is crucial in design of hot and cold water systems. Lack of adequate pressure is one of the most frequent complaints in houses. The pressure available for water distribution within a building can come from various sources. If the pressure from the public mains is inadequate for building operation, other means must be provided for increasing the pressure to an adequate level.
1.3 ThePresent Work
To tackle the problem of inadequate pressure in houses, the present work focuses on the design of the water supply for a three bedroom bungalow, to ensure water supply at adequate pressure on all fixtures and equipment at all times and to achieve the most economical sizing of the pipes.
1.4 Aim and Objectives
The aim of this research is to design a water supply system for a three bedroom bungalow to ensure adequate pressure. The specific objectives are to:
i. Carry out the design analysis of the piping system
ii. determine the adequate flow pressure
iii. determine the flow rate at outlet
iv. determine the constant pressure range
v. determine the pipe size
vi. determine the loading unit
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1.5 Significance of the Study
The importance of adequate pressure cannot be over emphasised. Where water is drawn from public water mains, the public water mains must supply water with adequate pressure to meet the peak demand of all buildings in the area otherwise there is high risk of back flow and subsequent contamination of the mains from the buildings (Ho, 2010).
1.6 Scope of the Study
This study is limited to the design of water supply system for a three bedroom bungalow of about eight occupants.
1.7 Definition of Operational Terms
Maximum flow: Maximum flow or maximum possible flow is the flow that will occur if the outlets on all the fixtures are opened simultaneously. An average flow is that flow likely to occur in the piping under normal conditions. Maximum portable flow is the flow that will occur in the piping under peak conditions. It is also called peak conditions or peak flow (Hazen, 2000).
Demand type: Some outlets impose what is called a continuous demand on the system. They are differentiated from the outlets that impose an intermittent demand. Outlets such as hose bibs, lawn irrigation, water cooling and similar flow requirements are considered to be continuous demand. They flow for an extended period of time. Plumbing fixtures draw water for a relatively short period of time and are considered as imposing an intermittent demand (Mui et al., 2007).
Estimating demand: The basic requirement for estimating demand call for a method that:
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i. Produces estimates that are greater than the average demand for all fixtures or inadequate supply will result during the period of peak demand.
ii. Produces an accurate estimate of demand to avoid over sizing.
iii. Produces estimate for demand of groups of the same type of fixtures as well as for mixed fixture types (Mui et al., 2007).
Loading Unit (LU): A factor given to an appliance relating the flow rate at its terminal fitting to the length of time in use; frequency of use for a particular type; use of building; evaluate the „probable maximum. It also relates the flow rate to the probable usage and consider design and minimum flow rates (Ho, 2010).
Flow pressure: It is essential that the term flow pressure can be thoroughly understood and not confused with static pressure. Flow pressure is that pressure that exists at any point in the system when water is flowing at that point. It is always less than the static pressure. To have flow, some of the potential energy is converted into kinetic energy and additional energy is used in overcoming friction which results in a flow pressure that is less than static pressure.
Flow at an outlet: There are many times when the engineer must undermine how many gallons per minutes are being delivered at an outlet. This can easily be determined by installing a pressure gauge in the line adjacent to the outlet and leading to the gauge while flow is occurring at a known flow pressure.
Constant flow: Pressures in the various parts of the piping system are constantly fluctuating depending on quantity of flow at any moment. Under these conditions the rate of flow of from any outlet will vary with change of pressure (Ladd, 2005).
Design load: In structural analysis, design load is the total load on a structural system under the worst possible loading conditions.
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Fitting: Any apparatus, cistern, cock, equipment, machinery, material, tank, tap and valve; and any appliance or device other than a meter, which is installed or used in a fire service or inside service.
Direct Supply System: A plumbing system which conveys water directly from the government water mains to the point of usage without any transit water storage tanks.
Indirect Supply System: A plumbing system which conveys water from the government water mains to the point of usage through a transit water storage tank.
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