WorksheetsScientific principles worksheet 1 - 3
Total questions: 25
Worksheet time: 13mins
Hard water is produced when rainwater falls onto which type of ground?
Limestone or chalk bedrock
Granite and basalt outcrops
Clay-rich soils
Coastal sand dunes
Where in the UK is hard water found, and how is hardness in water measured?
Mostly in the South and East of England; measured in parts per million PPM
Mostly in Highland Scotland; measured in parts per billion of iron
Mostly in Wales; measured by electrical conductivity in siemens
Mostly in Northern Ireland; measured in cubic metres per second
Above what temperature do calcium carbonates start to leave hard water?
40 °C
65 °C
80 °C
100 °C
How does the answer in question 3 affect a hot water system – pipework, cylinder, boiler and draw off points?
Limescale deposits form, reducing heat transfer and narrowing pipes
Water becomes acidic and dissolves copper pipes quickly
Pressure rises and valves fail due to gas expansion
Hot water becomes unsafe to drink due to bacterial growth
What is the pH number for pure water?
5
7
9
11
What is a drawback of soft water?
It is corrosive to some metals and fittings
It freezes at a higher temperature than hard water
It cannot be heated efficiently
It creates scale in kettles and cylinders
What is latent heat?
Heat absorbed or released during a change of state without temperature change
Heat lost from a surface by convection only
Heat required to raise 1 kg of water by 1 °C
Heat measured by a thermometer at boiling point
Describe what a pure metal is and where the metal could be used in a plumbing situation.
A single elemental metal with no alloying, such as copper used for pipework
A mixture of metals tailored for strength, such as brass used for valves
A metal coated with zinc to resist rust, such as galvanized steel
A polymer reinforced with fibres used for flexible hoses
What does a ferrous material contain?
Iron
Aluminium
Copper
Carbon only
What is a disadvantage of a ferrous material?
It is prone to rusting and corrosion
It cannot be magnetised
It is always lighter than water
It melts at very low temperatures
What is an alloy?
A combination of two or more elements, at least one a metal, to improve properties
A single pure metal with no impurities
A plastic reinforced with fibres
A ceramic formed from clay
Name two alloys used in the plumbing industry and where they may be found.
Brass for fittings and valves; solder for joints
Bronze for rafters; pewter for roofing
Stainless steel for gutters; nichrome for radiators
Titanium for cisterns; duralumin for taps
What plastic is commonly used as the underground mains and the service pipe to a property?
MDPE (medium‑density polyethylene)
PVC‑U (unplasticised polyvinyl chloride)
ABS (acrylonitrile butadiene styrene)
PEX (cross‑linked polyethylene)
What plastic can be used to supply hot and cold water to the draw off point inside a domestic property?
Polybutylene
PVC‑U waste pipe
ABS solvent‑weld waste
MDPE service main
Which plastic is used on waste discharge branches and can be solvent welded?
ABS
Polypropylene (PP)
MDPE
HDPE
What is density equal to?
Mass per unit volume
Weight per unit length
Pressure per unit area
Energy per unit time
What is the relative density of water?
0
1
10
1000
Why will LPG sink to the floor?
It is denser than air
It is colder than air
It reacts with moisture in air
It is lighter than air
What does ductile mean?
The ability of a material to be reshaped without breaking.
Easily dissolved in water
Able to resist impact without deformation
Unable to conduct electricity
Name a malleable material.
Lead
Glass
Cast iron
Granite
How is corrosion on the inside of LCS central heating pipework prevented?
Dose the sealed circuit with corrosion inhibitor to maintain a protective film
Use only plastic radiators
Increase the flow velocity to scour deposits
Install copper cylinders only
When using LCS pipework for hot water systems, how is corrosion prevented?
Use galvanized steel pipework/coatings to protect against rust
Install uncoated mild steel to allow natural passivation
Avoid any inhibitors to prevent chemical attack
Use aluminium fittings throughout
What do the letters DZ, stamped on a modern brass fitting, mean?
Dezincification‑resistant
Double‑zoned
Dry‑zone rated
Design size
Describe electrolytic corrosion.
Corrosion caused by a galvanic cell when dissimilar metals contact via an electrolyte
Corrosion caused solely by high temperature
Corrosion from mechanical wear only
Corrosion that occurs only in pure distilled water
In a domestic hot water cylinder there is quite often a sacrificial anode. What material is this generally made of?
Magnesium
Copper
Zinc
Aluminium
