plumbing principles

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Unit 004SCIENTIFIC PRINCIPLES

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Section1

Measurements used in

Mechanical Services

Measurement

(The S.I. Metric system)

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WHAT ARE WE GOING TO COVER

TODAY?

THE S.I. UNITS OF MEASUREMENTS USED IN PLUMBING

Measurement

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Measurement

The S.I. system is the system that has been adopted for

the U.K.

from existing metric systems.

S.I. Stands forSysteme Internationale.

The construction industry uses Sub units milli but NOT

the centi. i.e. millimetres, but not centimetres.

However, since the introduction of metrication, the centiis becoming increasingly popular.

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Measurement

1 Metre = 1000 millimetres (mm)

1 Bar = 1000 millibars (mb)

1 Bar also equals 100 kilo pascal (Kpa)

1 kilo pascal (Kpa) = 1 kilo Newton per meter squared (1kN/m2

) 1 Kilogram = 1000 grams (g)

1 sq. metre = 1,000,000 sq. millimetres

1 Bar = 10 meters of head

NB Milli = one thousandth of

Kilo = one thousand times

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Measurement

TIME IS MEASURED IN;

Hours, Minutes and Seconds (s)

1hr = 60mins 1min = 60 seconds

3600 seconds = 1hr (60x60 = 3600)

Seconds (s) are the preferred method

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HEAT AND TEMPERATURE

Measurements

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Measuring Temperature

Latent Heat

Thermal expansion

Heat and Temperature

TEMPERATURE

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The main difference between heat and temperature is that heat is

recognised as a unit of energy, measured in joules.

temperature is the degree of hotness of a substance

heat is the amount of heat energy (j) that is contained within asubstance.

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An example of this which is shown in a number of text

books is a short length of Steel wire heated until it is

red hot and a bucket of hot water.

The temperature of the wire is 350C

The water has a temperature of70C

The wire is far hotter, but actually contains less

heat energy.

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The S.I. unit of temperature measurement is the

degree Kelvin, the most common unit used in

plumbing is degrees Celsius (centigrade) written as C

An other unit used is Fahrenheit, it is some times

necessary to convert from one scale to an other.

MEASURING TEMPERATURE

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Temperature scale

The difference between two fixed points is divided

into 100 equal parts, each called a degree. The ice

point is 0C and the steam point 100C. This method

was devised by a Swedish astronomer named Celsius,

and is now called the Celsius scale.

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The Kelvin scale like Celsius uses single degree

increments but the freezing point is 273.15k and the

boiling point 100 degrees higher at 373.15k

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Absolute zero is theoretically the lowest possible

temperature that can ever be reached. To convert

from C to k add 273.15 and to convert from k to C

subtract 273.15. no temperature in Kelvin is negative

but Celsius is negative when it drops below 0C

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Converting to Fahrenheit

Celsius Location Fahrenheit

0 Freezing point of (water) 32

4 Maximum density (water) 39.2

20 Average room temperature 68

36.8 Blood temperature 98.4

43.3 Bath water 110

60 Washing-up water 140

65 Primary return 149

85 Primary flow 185

100 Boiling point (water) 212

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Converting to Fahrenheit using mathematics

Fahrenheit has 180 divisions and starts at 32

Celsius has 100 divisions and starts at 0

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This means that 9 divisions in Fahrenheit are equalto 5 divisions Celsius

To put it an other way 1 degree Celsius is 95times

greater than 1 degree Fahrenheit

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As Fahrenheit starts at 32. Therefore the formula for

converting from Fahrenheit to Celsius is Degrees

Celsius = Degrees Fahrenheit32 x 59

The formula for converting from Celsius to Fahrenheit

is Degrees Fahrenheit = Degrees Celsius x 9 + 32

5

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WORKED EXAMPLE

Convert 212 Fahrenheit to degrees Celsius

Degrees Celsius = degrees Fahrenheit 32 x 5

9Degree Celsius = 212 32 x 5

9

Degree Celsius = 180 x 59

Degree Celsius =100C 212F = 100 C

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Worked example

Convert 20 Celsius to degrees Fahrenheit

Degrees Fahrenheit = degrees Celsius x 9 + 32

5Degrees Fahrenheit = 20 x 9 + 32

5

Degrees Fahrenheit = 4 x 9 + 32

Degrees Fahrenheit = 36 + 32

Degrees Fahrenheit = 68 C 20 C = 68 F

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We have looked at the complicated method, lets now

look at the simpler method,

Celsius to Fahrenheit = (C x 1.8) + 32 = F

Fahrenheit to Celsius = (F 32) x 0.56 = C

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Convert 212 Fahrenheit to degrees Celsius

Degrees Celsius = (F 32) x 0.56 = C

Degrees Celsius = (212-32) x 0.56

Degrees Celsius = 100.8 C

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Convert 20 Celsius to degrees Fahrenheit

Celsius to Fahrenheit = (C x 1.8)+ 32

Degrees Fahrenheit =(20 x 1.8)+ 32

Degrees Fahrenheit = 68 F

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Devices used to measure temperature

Now see

SmartScreenWorksheet 8

Temperature

measurement

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There are three forms of state in which a substance

can exist,

Solid

Liquid

Gas

LATENT HEAT

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Water exits in three states ice (solid), water (liquid),

gas (steam).

The change of state from solid to liquid or vice versa is

termed the lower change of state andthe change

from a liquid to a gas istermed theupper change of

state

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Heat that brings about a change in state with no

change in temperature is called latent (hidden) heat.

When a substance changes state the temperature

stays the same. It is the addition or removal of the

heat that produces the change of state.

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Heat which causes a change in temperature in asubstance is called sensible heat.

When ice turns to water it is changing state from a solidto a liquid. In order to achieve this the ice requires

additional heat energy. The heat being applied to the ice

is used to change state. During this period there is no

increase in temperature, although the heat is still being

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When the ice has completely turned to water, the

temperature will begin to rise again. When the ice has

completely turned to water, the temperature will

begin to rise again.

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When the reverse happens I.e. water turns to ice, the

change of state being liquid to solid, there is a surplus

of energy I.e. heat energy is given off. This counteractsthe cooling effect and there is no drop in temperature

until all the water has turned to ice, the temperature

then continues to drop.

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This happens whenever a substance changes state, so

it will also happen when water turns to steam. I.e. the

temperature of the water will reach 100 C, but will

not increase until the water has turned to steam.

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In reverse, the steam will turn to water and during

this time, the temperature will not fall until all the

steam has turned to water. During this time latent

heat is given off.

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Ice

to

water

A B C D E

100

0

Water to steam

Heat input joules

TemperatureC

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Now in your own words on the note page provided

sum up the following terms,

MELTING

FREEZING

BOILING

EVAPORATING / EVAPORATION

CONDENSING35


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From point A to point B the temperature is rising

steadily. The heat being absorbed during this period is

called sensible heat because it can be sensed by the

thermometer. From B to C it is apparent that heat is

still being absorbed but it is not visible on the

thermometer

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From B to C it is apparent that heat is still being

absorbed but not visible on the thermometer, so it is

called latent heat because it cannot be seen.

From C to D the thermometer shows the second

increase in sensible heat and from D to E shows

latent heat again.

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Heat and Power


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Heat and Power

Recovery Rate

This is the

amount of time

required to heatup a quantity of

water to a

specifictemperature

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Heat and Power

Heat Recovery Period

This time will vary depending upon the heat source

power rating.

It is possible to calculate the heat recovery period.

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Measurement (RECAP)

TIME IS MEASURED IN;

Hours, Minutes and Seconds (s)

1hr = 60mins

1min = 60 seconds

3600 seconds = 1hr (60x60 = 3600)

Seconds (s) are the preferred method

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H t d P


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Heat and Power

Using this formula:

SH x Kg x temperature riseAvailable time in seconds

SH = the specific heat of water(the amount of

energy required to heat 1kg of water by 1C)

Kg = the weight of water to be heated

= Power Required

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Heat and Power

Example: Find the power required to heat a cylindercontaining 100 litres of water to 60C

Incoming water supply temperature = 4C

Customer requires water, to be at 60C, in 1hours

SH x Kg x temperature rise

Available time in seconds

= Power Required

4.2 x 100 x 56 23520

90 x 60 5400

= = 4.36 kW

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Heat and Power

This example does not allow for heat loss and the heating-up of the

HWSC. It is advisable to add 10% which will allow for this loss.

e.g. 4.36 + 10% =4.36 +

0.43

4.79 kW

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Heat and Power

Example: Find the power required to heat a cylinder containing

125 litres of water to 60C


Customer requires water, to be at 60C, in hour



= Power Required

4.2 x 125 x 4 2 22050

30 x 60 1800=

= 12.25 kW

+ 1.22 10%

13.47 kW

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H t d P


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Heat and Power

Often the house owner will want to know how long it

should take to heat a cylinder of water.

This can also be found using the same formula with a

bit of transposition:


Available time in SecondsPower (kW)

= time in secondsPower Required

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H t d P


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Heat and Power

Often the house owner will want to know how long it

should take to heat a cylinder of water.

This can also be found using the same formula with a

bit of transposition:

SH x Kg x temperature risePower Required = time in seconds



= Power Required

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H t d P


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Heat and Power

Example: Find out how long it will take to heat a cylinder containing

136 litres of water to 60C, using the 3kW immersion heater.



Power (kW)= time in seconds

4.2 x 136 x 56

3 = 10662 seconds

= 177 minutes = 2 hrs 57mins10662

60 47

H t d P


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Heat and Power


150 litres of water to 60C, using the 27kW gas boiler.




4.2 x 150 x 47

27 = 1097 seconds

= 18 minutes1097

60 48

H t d P


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Heat and Power

Example: Find the power required to heat a cylinder containing 130

litres of water to 60C.Incoming water supply temperature = 12C

Customer requires water to be at 60C, in 1hour

Example: Find out how long it will take to heat a cylinder containing 115litres of water to 60C, using the 23kW gas boiler.


Example: Find out how long it will take to heat a cylinder containing 120litres of water to 60C, using the 3kW immersion heater.


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H t d P


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Heat and Power

Example: Find the power required to heat a cylinder containing130 litres of water to 60C.


Customer requires water, to be at 60C, in 1hour


Available time in seconds= Power Required

4.2 x 130 x 48 262081 x 60 x 60 3600

== 7.28 kW

+ 0.72 10%

8.00 kW

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Heat and Po er


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Heat and Power


115 litres of water to 60C, using the 23kW gas boiler.



Power (kW)

= time in seconds

4.2 x 115 x 55

23 = 1155 seconds

= 19 minutes1155

60

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Heat and Power


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Heat and Power


120 litres of water to 60C, using the 3kW immersion heater.




4.2 x 120 x 46

3

= 7728 seconds

= 129 minutes = 2 hrs 9mins7728

60

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Heat and Power

SPECIFIC HEAT CAPACITY

The specific heat capacity of a substance or material is

the amount of heat required to raise the temperature

of1kg of the material by 1C. the heat required varies

depending on the material.

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Heat and Power

E.g. the heat required to raise 1kg of water by 1C is

4.186kJ and 0.125kJ would be required to raise 1kg of

lead by 1C

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Material kJ/kgC

Water 4.186

Aluminium 0.887

Cast Iron 0.554

Zinc 0.397

Lead 0.125

Copper 0.385

Mercury 0.125

Heat and Power

Specific Heat Capacity Values

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Heat and Power


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HEAT TRANSFER

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Heat and Power

There are three methods of heat transfer :

Conduction

Convection

Radiation

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Heat and Power

Conduction

Conduction is the transfer of heat energy through a

material. This happens because of the increased

vibration of molecules, which occurs when materialsare heated.

The vibrations from the heated material are then

passed on to the adjoining material, which then heatsup in turn.

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Heat and Power

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Heat and Power

Some materials are better conductors than others

Metals tend to be good conductors

Wood is a poor conductor of heat

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Heat and Power


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Heat and Power

Copper is a better conductor of heat than steel, ironand lead. Wood plastics which are poor conductors of

heat are known as thermal insulators

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Heat and Power

Convection

Convection is the transfer of heat by means of movement of a

locally heated fluid substance (usually air or water). As fluid is

heated the process causes expansion which in turn causes a

lowering of its density. The less dense warm flue begins to

rise and is replaced by cooler, denser fluid from below.

Eventually convection currents are set up which allow for a

continuous flow upwards from the source.

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Heat and Power

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Heat and Power

Radiation

Radiation is the transfer of heat from a hot body to a

cooler one. It does not need a material medium to do

this. It needs only air and uses heat waves.

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Heat and Power


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Heat and Power

Radiation can be sensed on a sunny by the heat of the

sun. Some materials absorb heat radiation better

than others. Colour often plays apart, dull matt

surfaces will absorb radiation heat better than shiny

polished surfaces.

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Heat and Power


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Heat and Power

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Heat and Power


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Heat and Power

Now in your own words on the note page provided

sum up the following terms,

CONVECTION

CONDUCTION

RADIATION

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THERMAL EXPANSION

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Most materials will expand when heated. This

because the molecules in a substance move about

more vigorously when heated. The molecules will

then move further apart from each other, this will

mean that the materials taking up more volume.

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When a material cools the molecules slow down and

move closer together, thus the material gets smaller

or contracts. The amount a material expands in length

can be calculated using the following formula.

Length (m) x temp rise (C) x coefficient of linear

expansion

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Material Coefficient C

Plastic 0.00018

Zinc 0.000029

Lead 0.000029

Aluminium 0.000026Tin 0.000021

Copper 0.000016

Cast iron 0.000011

Mild Steel 0.000011

Invar 0.00000009

Now look at SmartScreen hand-out 1 & 2 Properties of materials

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Worked Example

Calculate the amount a 4m long plastic discharge stack will expanded

due to a temperature rise of 24C.

Amount of Expansion = 4 x 24 x 0.00018*

Amount of Expansion = 0.0172m or 17.28mm

*Figure take from chart

Now look at SmartScreen hand-out 9 Expansion of liquids and work

sheet 4 Heat and power 72

PROPERTIES OF WATER


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Classification of water

Corrosion

Specific heat capacity

Heat transfer

Capillary attraction

Siphonage

PROPERTIES OF WATER

What are we going to look at?

Properties of Water


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Properties of Water

Water is a chemical compound which is made up of Hydrogen and

Oxygen (H2O). An important property of water is its solvent power.

It has the ability to dissolve some gases and solids to form

solutions.

CLASSIFICATION OF WATER

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Properties of Water

The purest form of water is rain water which is collected on the

open countryside. It contains dissolved gases such as nitrogen,

oxygen and carbon dioxide, this doesnt affect its potability

(suitability for drinking)

Water may be classified as having varying degrees of

hardness or softness

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Properties of Water

Permanent hardness occurs as a result of the natural solvency

of pure water. It will dissolve sulphates of limestone. A symptom of

hard water is the difficulty in forming a lather with soap.

Temporary hardness is responsible for the hard scale which can

accumulate on the inside of boilers, pipework and cylinders. It will

restrict the flow of water, reduce the efficiency of appliances which

can lead to system failure.

Water Hardness

Water hardness can be described as temporary or permanent.

Properties of Water


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Properties of Water

Water that is Soft will enable a lather to be produced soap easily.

This is because of the absence of dissolved salts such as Calcium

Carbonates and Calcium sulphates.

pH Value

The term pH value refers to the level of acidity or alkalinity of a

substance. Pure water has a pH of 7.0. If water dissolves acidic

materials, the pH falls and if it dissolves alkaline materials the pH

rises.

Properties of Water


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p

Acidic and alkaline water can both damage the materials used in

plumbing systems, by causing corrosion. Metals are particularly at

risk from corrosive effects of acids and alkalis.

Slightly acidic water will break down materials in plumbing

systems, resulting in the build up of silt and other debris in the

system.

Rainwater is naturally slightly acidic, due to small amounts of

carbon dioxide and sulphur dioxide in the atmosphere dissolved

into it, forming very weak carbonic and sulphuric acids.

Properties of Water


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p

Properties of Water


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p

There are four main causes of corrosion

The effects of air

The effects of water

The direct effects of acid, alkalis and chemicals.

(from environmental sources)

Electrolytic action

CORROSION

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p

Atmospheric Corrosion

Pure air and water have little corrosive effects, but together in the

form of moist air(oxygen + water vapour)they can attack ferrous*metals such as steel and iron very quickly to form iron oxide or

rust.

*Metal that contains iron

Properties of Water


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p

The corrosive effects of rusting can completely

destroy metal

Properties of Water


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Gases such as Carbon dioxide, sulphur dioxide and sulphurtrioxide which can be found in our atmosphere, will also increase

the corrosive effects air has on certain metals, especially iron,

steel and Zinc.

These gases are often found near industrial areas as these gases

are often waste products from various industrial processes.

Properties of Water


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Coastal areas also suffer from increased atmospheric corrosion

due to the amount ofsodium chloride (salt) from the seawhich

become dissolved into the local atmosphere.

Non- ferrous metals such as copper, aluminium and lead, have

significant protection against atmospheric corrosion. Protective

barriers usually sulphates form on these metals to prevent further

corrosion. This protection is called a patina

Properties of Water


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Corrosion by Water

Ferrous metals are particularly vulnerable to the effects of

corrosion caused by water. The effects of this corrosion are

commonly seen in central heating systems as black ferrous oxide

and red rust (Haematite and Magnetite) build up in radiators.

A by-product formed from this action is hydrogen gas which

accumulates in the radiators. The build up can be released by

bleeding the radiators.

Properties of Water


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Properties of Water


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If the water in an area has a high acidity (soft water ) the internal

wall of the copper may become slightly discoloured. This will not

affect the safety or quality of the drinking water.

If there is lead pipework within a building there is a risk of the

water dissolving minute quantities of lead, this contaminating the

water. This may have toxic effect especially for children.

Properties of Water


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The Direct Effects of Acid, Alkalis and Chemicals.

(From environmental sources)

Some types of wood (such as oak) have a corrosive effect on

lead, latex cement and formed concrete will adversely affect

copper.

Properties of Water


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Heavy clay soils may contain sulphates which can corrode lead,

steel and copper. Grounds containing ash and cinders are also

very corrosive as they are strongly alkaline, if pipes are to be laid

in such ground they should be wrapped in protective material

Properties of Water


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Electrolytic action is caused when two very dissimilar metals come

into contact with each other. The process involves the flow of

electrically charged ions from an anode to a cathode through a

medium known as the electrolyte (this is usually water)

ELECTROLYTIC ACTION

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This process is called electrolysis. It will lead to the destruction of

the anode. The time that it takes to destroy the anode will depend

on :

The properties of the water that acts as the electrolyte, if the

water is hot or acidic the rate of the corrosion will increase

The position of the metals that make up the anode and cathode

in the electromotive series

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The list on the next slide shows the common elements used in the

plumbing industry. The order in which they appear indicates their

electromotive properties.

Properties of Water


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Copper Cathodic

Tin

Lead

Nickel

Cadmium

Iron

Chromium

Zinc

Aluminium

Magnesium Anodic

Properties of Water


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The elements higher up the list will destroy those lower down

through electrolytic corrosion. The further the elements are to

each other the faster the corrosion takes place.

Properties of Water


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This problem needs to be recognised by plumbers, especially if

metal such as copper and galvanised tube and copper fitting arein direct metallic contact. If these metallic elements are

surrounded by water or damp ground, a basic electrical cell is

created and electrolytic corrosion can take place.

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Properties of Water


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Capillary attraction is when a liquid is drawn up through a small

gap between the surfaces of two materials.

Capillary attraction occurs due to two characteristics of most

liquids.

CAPILLARY ATTRACTION

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Adhesion is the ability to stick to a surface. Water in a smal tube

such as a U gauge (manometer), has a curved surface where the

water adheres to the sides of the tube. This is called the meniscus

Properties of Water


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Meniscus

Properties of Water


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Adhesion

Properties of Water


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Cohesion is the ability of a liquid to pull itself into a ball. This is

also called surface tension. A simple illustration of this is

rainwater laying on a well-polished car

Properties of Water


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Cohesion

Properties of Water


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When planning the installation of sheet lead weathering, the affect

of capillary attraction needs to be taken into account. Water can

penetrate a building via a lapped joint, as the materials are closed

together.

Properties of Water


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Properties of Water


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This can be avoided by installing an

anti-capillarity groove,

this will prevent water entering the building

Properties of Water


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Capillary attraction can also take place within an S trap often

found under sinks, if a piece of dish cloth becomes lodged in tothe in the trap. Capillary attraction could take place. This can lead

to the loss of the trap seal and smells filtering back into the home

from the drains

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Properties of Water


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Principles of Siphonage

Atmospheric pressure is the key to siphonage. Siphonage works

when atmospheric pressure is able to force water through a tube

i.e. a length of hose pipe. It may appear that it is going against

the force of gravity.

For siphonage to work the air pressure in the tube must be

reduced below that of atmospheric pressure.

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Properties of Water


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Siphonic Wcs

Common uses of symphonic action are found

on Wcs

Properties of Water


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Properties of liquids and gases


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p q g

Liquids used in Mechanical services consist of:

Water

Refrigerant

Anti- freeze- glycol mixes

Fuel oils

Lubricants / Greases



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p q g

WATER

Widely used in the industry.

IE Cold water, Hot water, Heating, Etc.

H20- Hydrogen 2 parts and oxygen 1 part.



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p q g

REFRIGERANT

Used in Air conditioning, freezers and fridge

units and heat pumps.

Mixture of chemicals and gasses in order to

perform at extreme temperatures

Data sheets for refrigerants

http://localhost/var/www/apps/conversion/tmp/scratch_4//Staff06/data/dshare/FACULTY%20OF%20CONSTRUCTION/PLUMBING/COURSES%20WE%20ARE%20TEACHING%20TEACHING/COURSES/NVQ%20DIP%20PLUMBING%20AND%20DOM%20HEATING/LEVEL%202/Theory/Unit%20004%20-%20Scientific%20Principles/Data%20sheets%20for%20.%20refrigerants.htmhttp://localhost/var/www/apps/conversion/tmp/scratch_4//Staff06/data/dshare/FACULTY%20OF%20CONSTRUCTION/PLUMBING/COURSES%20WE%20ARE%20TEACHING%20TEACHING/COURSES/NVQ%20DIP%20PLUMBING%20AND%20DOM%20HEATING/LEVEL%202/Theory/Unit%20004%20-%20Scientific%20Principles/Data%20sheets%20for%20.%20refrigerants.htm


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ANTI- FREEZE / GLYCOL MIXES

Used in solar thermal panels, combustion

engines, Etc.

Mixture of chemicals in order to perform at

extreme temperatures

Product data sheet

http://localhost/var/www/apps/conversion/tmp/scratch_4//Staff06/data/dshare/FACULTY%20OF%20CONSTRUCTION/PLUMBING/COURSES%20WE%20ARE%20TEACHING%20TEACHING/COURSES/NVQ%20DIP%20PLUMBING%20AND%20DOM%20HEATING/LEVEL%202/Theory/Unit%20004%20-%20Scientific%20Principles/Glycol%20mix%20.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_4//Staff06/data/dshare/FACULTY%20OF%20CONSTRUCTION/PLUMBING/COURSES%20WE%20ARE%20TEACHING%20TEACHING/COURSES/NVQ%20DIP%20PLUMBING%20AND%20DOM%20HEATING/LEVEL%202/Theory/Unit%20004%20-%20Scientific%20Principles/Glycol%20mix%20.pdf


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FUEL OILS & Lubricants / Greases

Fuel oils are mainly used for heating purposes,

however majority of mechanical moving parts

require an oil or grease as a lubricant.

Carbon Based non renewable taken from the

earth and refined into the above products at

various levels



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Gases used in Mechanical services consist of:

Air and steam

LPG Liquid Petroleum Gas

Natural Gas

Carbon Dioxide

Refrigerant Gasses



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Air and Steam

These are mainly used for producing pressure in

order to drive industrial machinery.



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LPG Liquid Petroleum Gas

A gas that is used to heat homes and for cooking

in rural areas not on mains gas. You use this gas

for soldering, camping and caravan, boats etc.

Factories may use this for localised heating.



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Natural Gas

Supplied from the gas mains, and currently the

most common gas used for heating buildings,

both domestic and industrial.



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Carbon Dioxide

Carbon dioxide in solid and in liquid form is used

for refrigeration and cooling. It is used as an

inert gas in chemical processes, in the storage ofcarbon powder and in fire extinguishers.

Pipe freezing kits may use this gas.



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Refrigerant Gases

Used in Air condition, freeze and fridge units

and heat pumps.

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Mass and weight

Density liquids and gases

Relative density

Pressure

g

What are we going to look at?

Properties of gasses


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Temperature of Gases.Properties of Gases

(Typical Values)

Quality/Unit Natural Methane Propane Butane

Chemical Formula CH4 C3H8 C4H10

Boiling Point -1620C -420C -20C

Relative Density (Liquid) - 0.5 0.57

Relative Density ( Gas) 0.58 1.78 2.0

Gross Calorific Value 38.5MJ/m3 95MJ/m3 121MJ/m3

Gas Family 2nd 3rd 3rd

Flammability Limits 5-15% 2.3-9.5% 1.9-8.5%

Air/Gas Ratio 9.81:1 23.8:1 30.9:1

Oxygen/Gas Ratio 2:1 5:1 6.5:1

Flame Speed 0.36m/s 0.46m/s 0.38m/s

Ignition Temperature 7040C 5300C 5000C

Maximum Flame Temp. 10000C 19800C 19960C

System Operating Pressure

21mb (+/- 2) 37mb (+/-5) 28mb (+/- 5)



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Gas Laws:

Charless Law At constant pressure, the volume of a given mass of an ideal gas increases or decreases

by the same factor as its temperature on the absolute temperature scale (i.e. the gasexpands as the temperature increases).[1]

Boyles LawBoyle's law (sometimes referred to as the BoyleMariottelaw) states that the absolute pressure and volume of a given mass of confinedgas are inversely proportional, if the temperature remains unchanged within a

closed system.[1][2]

Boyles Law 2

http://www.youtube.com/watch?v=IkRIKGN3i0khttp://en.wikipedia.org/wiki/Absolute_temperature_scalehttp://www.youtube.com/watch?v=J_I8Y-i4Axchttp://en.wikipedia.org/wiki/Pressurehttp://en.wikipedia.org/wiki/Volumehttp://en.wikipedia.org/wiki/Temperaturehttp://en.wikipedia.org/wiki/Closed_systemhttp://www.google.co.uk/imgres?imgurl=http://upload.wikimedia.org/wikipedia/commons/thumb/1/15/Boyles_Law_animated.gif/220px-Boyles_Law_animated.gif&imgrefurl=http://en.wikipedia.org/wiki/Boyle%27s_law&h=167&w=220&sz=210&tbnid=KZ4zZ_spLXnNqM:&tbnh=90&tbnw=119&prev=/search?q=boyles+law&tbm=isch&tbo=u&zoom=1&q=boyles+law&docid=rdA0z9EZwxqKHM&hl=en&sa=X&ei=ltYGT8WCNYSv8QPtt7DoCQ&ved=0CFgQ9QEwBg&dur=1152http://www.google.co.uk/imgres?imgurl=http://upload.wikimedia.org/wikipedia/commons/thumb/1/15/Boyles_Law_animated.gif/220px-Boyles_Law_animated.gif&imgrefurl=http://en.wikipedia.org/wiki/Boyle%27s_law&h=167&w=220&sz=210&tbnid=KZ4zZ_spLXnNqM:&tbnh=90&tbnw=119&prev=/search?q=boyles+law&tbm=isch&tbo=u&zoom=1&q=boyles+law&docid=rdA0z9EZwxqKHM&hl=en&sa=X&ei=ltYGT8WCNYSv8QPtt7DoCQ&ved=0CFgQ9QEwBg&dur=1152http://en.wikipedia.org/wiki/Closed_systemhttp://en.wikipedia.org/wiki/Temperaturehttp://en.wikipedia.org/wiki/Volumehttp://en.wikipedia.org/wiki/Pressurehttp://www.youtube.com/watch?v=J_I8Y-i4Axchttp://en.wikipedia.org/wiki/Absolute_temperature_scalehttp://www.youtube.com/watch?v=IkRIKGN3i0k


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Heat pump / Refrigeration cycle

Drawing and stages

Plumbing Science
http://www.vent-axia.com/heatpump/howhttp://www.vent-axia.com/heatpump/how


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Mass in its simplest terms is the amount of matter in an object. It is

measured in grams or kilogram's. An objects mass will stay the same

unless parts are removed from it.

A basin tap will have the same mass, if it is on a work bench or on the

moon.

MASS

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The weight of an object is the force exerted by its mass, due to the

acceleration owing to force ofgravity.

On the earth all objects are being accelerated towards centre of the

planet. This is due to the earths gravitational pull.

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Pull exerted by gravity on mass of an object is known as its weight . We

measure weight in Newton's.

A Newton is equivalent to

1 metre per second (m/s2) per 1kg of mass.


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Plumbing Science


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On the Earth

The gravitational pull of the earth is 9.8m/s2

Therefore, an object with a mass of1kg on earth

would weigh 9.8 newtons

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On the moon

The gravitational pull of the moon is approximately 1.633m/s.

An object with a mass of1kg on the moon - would weigh 1.633

newtons.

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Mass of the object does not change whether it is on earth or on the

moon, but weight of an object changes immensely due to the reduced

gravitational pull of the moon.

Solid materials which have the same shape, can frequently have a

completely different mass. This is know as is density. The density of an

item is measured by its mass compared to its volume

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To calculate this the following formula is used

Density = mass

volume

Liquids and gases also have different densities, dependent on thenumber of molecules present within a particular volume of a

Substance.

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It is also very important to understand that the density of water changes

when temperature of water changes. Water is less dense when heated.

1m3 of water at 4C has a mass of 1000Kg

1m3 of water at 82 C has a mass of 967Kg

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Air

Polystyrene

Lead

Mass of all cubes are the same but volumes are different. Leadwill occupy a smaller volume than both air and the polystyrene,

due to its molecules being more tightly packed

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A mass that is concentrated in a smaller volume has a greater density

than a substance of equal mass that occupies a larger space.

Thus, gases have the smallest densities when compared to solids and

liquids. Gas molecules contain mostly empty space, while molecules in

liquids, are again more tightly packed together.

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Relative density (also known as specific gravity), is an effective way ofmeasuring the density of a substance or object and comparing its

weight per volume to an equal volume of water.

RELATIVE DENSITY

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1m3

of water has a mass of1000kg at 4C whereas 1m3

of lead weighsabout 11300kg. From this it can be seen that lead is 11.3 times heavier.

Knowing this, we can calculate weight of any substance by dividing

density of a substance by the density of water.

Water is always shown as 1.0

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Using this information, we know that any material with a higher numberthan 1.0 will sink in water and any number lower will float.

The relative density of gases can also be measured by comparing the

specific gravity of air, which is also expressed as 1.0

Material Relative density

Solids and Liquids

1 0


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Water 1.0

Class C fuel oil 0.79

Linseed oil 0.95

Aluminium 2.7

Zinc 7.1

Cast iron 7.2

Tin 7.3

Mild steel 7.7

Copper 8.9

Lead (Milled) 11.3

Mercury 13.6

Gases

Air 1.0

Methane ( Natural Gas) 0.6

Propane 1.5

Butane 2.0

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4c

10c

4c

1c

Maximum density of water 4C

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Relative Density of

Materials

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As water is heated, the process causes expansion, in - turn causes alowering density. The less dense warm water begins to rise, replaced by

cooler, denser fluid from below.

Eventually convection currents are set up, allowing a continuous flow of

heat upwards from its source.

Principles of mechanical advantage

and velocity ratios


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and velocity ratios.

Levers: What is a lever?In Basic form of a lever is a steel rod known as a

crowbar.

Wheel and axle: What is this?

In basic form a good example would be a car

steering wheel.


and velocity ratios


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Pulleys: What is this? A pulley is an arrangement of wheels with a

rope passed through them to enable the

movement of heavier objects. (block andtackle)


and velocity ratios


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Screws: What is this? A screw is used to lift an item under tension,

an example of this could be a acro .prop

Principles of basic mechanics


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Theory of moments.

Action and reaction.

Centre of gravity.

Equilibrium.

Using the Pcs Reach the above.

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Force will try to move an object

We cannot see force, however its effects can be seen in the next slide

FORCE

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Force

Force

Force is the cause of a

change in shape


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The unit of measurement for force is the Newton (N)

An object weighing 1 kg, dropped from a height, will travel at an

acceleration of 9.81 metres/second squared (m/s2) due to the earths

gravitational pull (gravity)


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Plumbing Science


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Force = Mass x accelerationForce = 50kg* x 9.81m/s2

Force = 490.5N

* 1Litre of water weighs 1kg

50kg

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Pressure can be defined as force acting over a specified area

Pressure is to act upon a wide variety of liquids and gasses in plumbing

applications e.g. air, water and oil. Pressure is involved in the delivery of

water that affects us most in plumbing.

PRESSURE


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Plumbing Science


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Pressure is measured in newtons per square metre (N/m2)

It is also known as Pascal (Pa)

You may have come across other terms used to identify pressure they

include (Bar or Pounds per square inch (ibs/in2)

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Static Pressure

Water will find its own level when exposed to atmosphere and with no

flow(static).

This occurs, what ever shape of the vessel in which water is placed, and

a result of gravitational force acting downwards on the water.

1 bar = 100,000N/m2 1lbs/in2 = 6894N/m2

Atmospheric pressure at sea level is 101,325N/m2

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Plumbing Science


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Pressure is exerted by solid objects in downwards

direction only, however, liquids exert pressure downwards

and sideways.

Plumbing Science

There are basically two ways of creating pressure in plumbing


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There are basically two ways of creating pressure in plumbing

systems:1. By connecting a pump into the system pipe-work; or

2. By using the weight of the water itself.

Plumbing Science


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The higher the column of water (plumbers call this head of

water) the greater pressure exerted at its lowest point.

Now look at SmartScreen hand-out 3 Water Pressure and Work

sheet 6 & 7

Plumbing Science


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Intensity of pressure or static pressure can be defined as force (KPa)

created by the weight of a given mass of water acting upon one unit

area (1m2).

Example:

Intensity of pressure = head x 9.18 KPa (gravitational force)

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Total Pressure is the intensity of pressure

multiplied by the area acted on.

Example:

Total pressure = intensity of pressure x area of base


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Now look at SmartScreen worksheet

3 Plumbing Materials

plumbing principles

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