Scientific Principles PPT 2 - Thermal Expansion & Corrosion

What is the coefficient of linear expansion?

• A measure of how much a material contracts when cooled

• A measure of how much a material expands when heated

• A measure of the density of a material

• A measure of the weight of a material

Why do plumbers need to consider the expansion of materials?

• To ensure pipes are colorful

• To prevent pipes from melting

• To accommodate changes when hot water flows through pipes

• To make pipes more flexible

What can cause plastic guttering to expand and creak?

• Cold weather

• Sunlight

• Heavy rain

• Strong winds

How much will a 6 metre length of lead expand if the temperature rises by 10°C?

• 0.00174m

• 0.00108m

• 0.00192m

• 0.00132m

What factors can influence the amount and speed of corrosion in materials?

• Wet conditions, gases, dissimilar metals, acids, heat, UV

• Dry conditions, pure metals, bases, cold, darkness

• Only wet conditions and heat

• Only UV and gases

What is the most common form of corrosion?

• Galvanization

• Rust (Oxidation)

• Tarnishing

• Patina

What elements are required for rust to form?

• Iron, nitrogen, and hydrogen

• Iron, water, and oxygen

• Iron, carbon, and sulfur

• Iron, helium, and neon

Why is an inhibitor added to the heating system water?

• To enhance heat transfer

• To prevent freezing

• To provide chemical protection for steel surfaces

• To increase water flow

What causes electrolytic corrosion?

• High temperature

• Presence of an electrolyte

• Lack of oxygen

• Excessive pressure

Which metals are mentioned as being part of a plumbing system that can experience electrolytic corrosion?

• Gold and silver

• Copper and LCS

• Zinc and tin

• Lead and mercury