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Published by Future Managers (Pty) LtdPO Box 13194, Mowbray, 7705Tel (021) 462 3572Fax (021) 462 3681E-mail: info@futuremanagers.netWebsite: www.futuremanagers.net

© Future Managers 2013

All rights reserved. No part of this book may be reproduced in any form, electronic, mechanical, photocopying, or otherwise, without prior permission of the copyright owner.

ISBN 978-1-77581-070-4

First published 19882nd edition 2013

To copy any part of this publication, you may contact DALRO for information and copyright clearance.

Any unauthorised copying could lead to civil liability and/or criminal sanctions.

Telephone: 086 12 DALRO (from within South Africa); +27 (0)11 712-8000 Telefax: +27 (0)11 403-9094 Postal Address: P O Box 31627, Braamfontein, 2017, South Africa www.dalro.co.za

FutureManagers

Contents

Module 1 Cold water supply .................................................................................................... 11.1 The characteristics of soft water ...................................................................................................31.2 The characteristics of hard water ................................................................................................. 31.3 Catchment areas ............................................................................................................................ 51.4 Fire-fighting equipment and regulations ................................................................................. 151.5 Domestic cold water installations ............................................................................................. 26 Exercises ....................................................................................................................................... 36

Module 2 Hot water supply ................................................................................................... 39

2.1 Pressure-reducing valves ............................................................................................................ 402.2 Pressure-relief valves ................................................................................................................... 472.3 Heating units ................................................................................................................................ 542.4 Indirect water heating and multi-storey installations ............................................................ 662.5 Hot water installation for a house ............................................................................................. 742.6 Hot water installation for multi-storey buildings ................................................................... 75 Trouble-shooting and possible remedies ................................................................................. 78 Exercises ....................................................................................................................................... 85

Module 3 Drainage ................................................................................................................... 89

Standard sanitary and miscellaneous abbreviations ........................................................................ 903.1 Drain gradients and excavations ................................................................................................913.2 Sewage disposal systems on plots and farms ........................................................................... 983.3 Drainage layouts ........................................................................................................................ 1043.4 The sewage purification process .............................................................................................. 1123.5 Drain tests .................................................................................................................................. 1183.6 Lifting sewage and stormwater, and subsoil drainage .......................................................... 1203.7 Sanitary ventilation systems ..................................................................................................... 124 Exercises ..................................................................................................................................... 132

Module 4 Sheet metal work and flashings .................................................................. 141

4.1 Sheet metal work and drawing practice ................................................................................. 1424.2 Flashings ..................................................................................................................................... 151 Exercises ..................................................................................................................................... 154

Module 5 Calculations .......................................................................................................... 161

5.1 Water pressure ............................................................................................................................1625.2 Hot and cold water pipe sizes, and gutter-sizing ................................................................... 1675.3 Installations ................................................................................................................................ 173 Exercises ..................................................................................................................................... 188

The aim of this volume is to assist the student who is keen to study in this particular field of the building trade.

The contents are compiled to cover the prescribed syllabus, and as a basis for those who intend studying further in this field to become professional, licensed plumbers.

No text book or other work of reference is ever complete. I therefore strongly recommend that students seek out all available sources to obtain the maximum amount of coverage on any particular topic, which would greatly enhance understanding of the subject matter.

College lectures and text books simply provide a theoretical background. Practical experience and/or on site observation of works in progress are of vital importance to complement the contents of these text books.

E.L. Julyan

Introduction

1MODULE

Cold water supply

When you go to the bathroom to wash your face, or to the kitchen sink for a glass of water, do you ever wonder how the water reaches these fixtures?• Wheredoesthewaterruntowhenyoupulltheplug?• Whatwillhappenifnowaterisreleasedintothecisternfeedingthewatercloset?• Howwillyoubathinwinterwithoutanelectricalgeyser?All these matters are plumbing-related, and that is why we need skilled plumbers.

PackingOrnamental hood

Counter nut

Tap handleSpindlePacking nut

Tap washer

Locking plane

Module outcomesOn completion of this module, you should be able to:• Interpretandunderstandtheapplicablehealthregulations• Interpretandunderstandthebuildingregulations• Recognisethedifferentpipetypesandtheirrespectivesizes• Readandunderstandapipelayoutdiagramwithitsrelevantpipesizes• Discussthekindsofwaterwithregardto:

– the characteristics of hard water– the causes of hard water– the characteristics of soft water– the causes of soft water– the method of softening hard water– theeffectofthekindsofwateronpipeinstallations

• Describe,withtheaidofaflowdiagram,thepurificationprocessofwater

2 Module 1 • Cold water supply

• Describe,withtheaidofdiagrams,thewatersupplytotheconsumerregarding:– supply tanks – supply towers– gravity system – a water reticulation system (grid)– pressure zones and zone valves

• Describetheuseandinstallationoffirehydrantsandfirereels• Namethevariousbuildingregulationsregardingtheflowratesandplacementoffire

fighting equipment (below)

• Planandsetout,withtheaidofdiagramswiththenecessarysymbols,acoldwaterinstallationforahouse,fromthewatermetertotheconsumerpoint:– with a supply tank– without a supply tank, from the water meter to the house

• Describethecauseofawaterhammer• Describetheremedyofawaterhammer• Describe,withtheaidofdiagrams,theworkingprinciples,usesandinstallationof:

– flushvalves– thermostatic valves– back-flowvalves– pressure-reducing valves – arrangement of a pressure-reducing valve– air-release valves

3Plumbing Theory N2

IntroductionWater originates naturally in the form of rain, hail or snow. Heat from the sun causes the water on the surface to evaporate to form clouds. This process of evaporation and condensation is repeated, and is known as the rain cycle for the particular region.

Water, however, has an extensive solvent power, and there are very few substances that do not dissolve in the water to some extent. The formation of rainwater is pure until it starts to rain, falls through the atmosphere and dissolves certain gases present, especially carbon dioxide. Carbon dioxide tends to make rainwater acidic, thus the term acid rain.

1.1 The characteristics of soft waterSoft water is an acid type that easily corrodes certain metal pipes, and in which soap lathers well.

1.2 The characteristics of hard waterWaterinwhichsoapdoesnotlaterwell,butgivesoffagreyishscuminstead,iscalledhard water. Hard water is healthy for humans, but reacts very negatively to pipes and boiler systems where hot water is used.

1.2.1 Temporary hard water

This is caused by bicarbonates of calcium or magnesium dissolved in the water. When the water is heated, the gas carbon dioxide, which holds the bicarbonates in solution, is drivenoff.Thebicarbonatethenchangestoinsolublecarbonates.To soften temporary hard water it can be boiled, but this is expensive and leaves a lime deposit.Oncethecarbondioxidehasbeendrivenoff,thewaterwillbeunabletoholdthe calcium bicarbonates in solution. It will reform to insoluble carbonates and settle, which causes furring on the inside of the systems.Alternatively slaked lime can be added. Water treated in this manner must, however, first be filtered before it is fed to any boiler system.

1.2.2 Permanent hard water

This is caused by the presence of sulphates of calcium and magnesium in the water. These salts are already dissolved in the water without the presence of carbon dioxide.

Permanent hard water cannot be softened by boiling, but needs chemical treatment such as the addition of washing soda (sodium carbonate). The sodium carbonate becomes sodium sulphate, which remains in solution in the water and is not harmful. Permanent hard water will not cause scaling or furring unless the water temperature and pressure are turned up very high, in which case it may cause corrosion.

Both temporary and permanent hardness can be removed by the base exchange method, which is more of a domestic process. When this exchange takes place between the chemicals, the water has a brackish taste.

4 Module 1 • Cold water supply

1.2.3 Purposes of the base exchanger

Theprocessremovesbothtemporaryandpermanenthardnessveryeffectivelybypassing the water through a base exchanger containing zeolite in the steel cylinder.

The zeolites in the cylinder have the property of exchanging their sodium base for magnesium or calcium base. For this reason it is called base exchanger.

Sodium zeolite + calcium sulphate or carbonate in water, becomes calcium zeolite (held back in softener) + sodium sulphate or carbonate (in solution with the water, but harmless).Thepurposeofthebaseexchangeristo:• conserve soap• improve the quality of water• improve the taste and odour of water.

Hardwater manhole

SaltSieve

Zeolite

Filter

to sewer

Drain cock

Rinse water pipe

Valves

Base exchanger

Process regenerating is as follows:Calcium zeolite (exhausted sodium) + sodium chloride (common salt) becomesodiumzeolite(regenerated)+calciumchloride(flushedtodrain).

1.2.4 Softening hard water with the base exchanger

Natural zeolite is in the form of quarts or silica, with other minerals such as sodium and calcium present.

5Plumbing Theory N2

The sodium in the water is given up in exchange for the calcium and magnesium, which causes the hardness in the water.

In time, the zeolite will become exhausted of its available sodium (table salt) and must then be regenerated.

Regeneration process

Sodium chlorides are added to strengthen the capacity of the zeolite.

The sodium zeolite that is present in the cylinder makes contact with the calcium sulphate or carbonated water, which is sent through the exchanger. With the chemical exchange that takes place in the cylinder, the sodium in the cylinder becomes calcium zeolite and the water takes up the sodium sulphate or carbonates in solution.

After some time, the sodium zeolite is converted to calcium and magnesium zeolite, thus losing its softening power. When this starts to happen, regeneration must be exercised in the base exchanger to replace the exhausted salt.

• Theflowinthetapsisreversed,sothatthewaterisrunninginanoppositedirection.In this manner, sediment matter will be drained away.

• After the exchanger is properly drained, a predetermined quantity of salt (sodium chloride) is added at the top of the exchanger.

When this is done, water is let in at a very slow rate at the top, to give sufficient time for the zeolite to absorb the sodium ions of the table salt.

The rinsing now continues until the taste of the water is fresh.• The taps are reversed back to the original state of supplying hard water through the

exchanger.

1.3 Catchment areasRainwaterdoesnotseepintothegroundtoremainthereforawhile;iteventuallyfiltersthrough to low-lying areas to form small streams, which in turn form rivers.

All countries have to build larger dams to meet the ever-increasing demand for water.

Very few dams in our country are free enough of pollution to provide pure drinkable water.Waterforthevastmajorityofdamsflowsthroughresidentialareas,pickingupallkinds of human and animal waste on its way. Storm water is invariably dirty, and varies in colour according to the amount of mud and sand that is picked up and carried along asitflows.

Retainingwallsarebuiltinriverbedstoformlargedams,fromwhichcitiesandtownsare supplied with water. Some villages and towns pump their water directly from rivers, butinthesecasestheriversarekeptflowingbydischargingwaterfromdamshigherup.

Forexample,KimberleyobtainsitswatersupplyinthiswayfromtheVaalRiver,which,duringthedryseason,iskeptflowingwithwaterreleasedfromtheVaalandBloemhofDams.

6 Module 1 • Cold water supply

1.3.1 Water supply systems

The gravity system

Thenameofthissystemindicatesthatthewaterflowsasaresultofpressureexertedby its own mass, from the storage dam, through all the stages of purification, until it reached the consumer. Pumping is not necessary at any stage.

The delivery pipe located at the base of the dam wall, is equipped with a sieve to prevent fish or loose objects from getting into the pipes. A coagulant such as aluminium sulphate is added to the water in proportionately measured quantities to cause mud in solution to settle at the bottom of the sedimentation tanks. The coagulant dissolves in the water and combines with the dust particles in suspension in the water, making them heavier so that they rapidly settle to the bottom of the tank.

Dams with clear water do not require sedimentation tanks. However, in most dams the water is muddy, particularly in the rainy season.

Dam

Sieve

CoagulantFilters

Chlorine

Control reservoir

Distribution reservoir

Gate valve

Sedimentationtanks

Reticulationsystem

The gravity system

The pump system

Most cities and towns have to pump their water supplies to higher levels in order to supply it to consumers.

Water is pumped from the dam or river to the top of a suitable hill, where the sedimentationtanksarebuilt.Fromhereitflowsthroughthefilterstothecontrolreservoir, from where it is pumped to the consumer’s reservoir, also located in a high position. Where no naturally high site is available for the consumer’s reservoir, as in numerous suburbs, the water has to be pumped twice and high water towers are built to cater for the residents of that suburb.

A diagram of the pump system appears on the next page.

7Plumbing Theory N2

Sedimentationtanks

Filters

Chlorine

Controlreservoir

Distributionreservoir

Gate valve

Reticulation system

Coagulant

Pump

Pump

Sieve

Dam

The pump system

The consumer reservoir

The consumer or service reservoir has to hold at least a two-day supply of water and provide sufficient pressure throughout the reticulation system so that all the consumers receive an adequate supply.

Fresh air inlets

Manholes Screening wire

Ballvalve

Gate valveMeteringchamber

Security fence

Main supply valve

Reticulation system

Two valves at corners

The consumer reservoir

Where possible the site should be excavated so that the reservoir, up to roof level, may be built underground. This ensures that the water will remain cool. The embankment and surrounding area is planted with grass to control dust. Manholes are incorporated intheroofforaccess,andventilatorstoensureaflowoffreshairintothereservoir.

The ventilators are protected with mesh and gauze to keep out birds and insects. The site is enclosed with a high security fence and gates, which are kept locked.

Reservoirsareperiodicallydrainedandcleanedout,becausethereisalwayssedimentaccumulatingonthefloorofthereservoir.