Plumbing Materials Properties PDF

PowerPoint 1 Properties of common plumbing materials LESSON INTENT Learners will be able to understand the main make up of different materials used in plumbing. By the end of the lessons all leaners will be able to describe the different forms of corrosion that can occur and effect on...

PowerPoint 1 Properties of common plumbing materials LESSON INTENT Learners will be able to understand the main make up of different materials used in plumbing. By the end of the lessons all leaners will be able to describe the different forms of corrosion that can occur and effect on plumbing materials. Learners will be able to describe the different properties of plumbing materials. Learners will be able to use the equations to work out coefficient of linear expansion and specific heat capacity.  Steel Iron Ferrous metals Non-ferrous metals Plastic Alloys Metals are some of the main materials used in plumbing: pipes, fittings, boilers, radiators. Pure metals Gained straight from ore, such as iron (ferrous), copper, aluminium, lead, zinc. Ferrous These are metals that contain iron. They are magnetic and will corrode easily if not treated (ferrous oxide or rust). Alloys A mixture of two or more metals, these are commonly used in the plumbing industry. Brass – copper and zinc Bronze – copper and tin Gunmetal – copper, tin and zinc Steel – iron and carbon. Non-ferrous metals Any metal that does not contain iron (copper, lead, zinc, aluminium etc).  QUESTION TASK List down how many different types of metals will we use as a plumber! If you have listed as many as you can then list where you find them! Plastics There are many different plastics that plumbers use on a daily basis. They can be used for cold water, hot water, central heating, guttering, above ground drainage and below ground drainage. Thermoplastic Made from polymer resin; can be heated and re- shaped but become brittle when frozen, (guttering). These plastics are recyclable. There are many types of thermoplastics, which are suitable for different situations.  Thermoplastics PVCu Unplasticised polyvinyl Not suitable for hot water chloride Solvent weld Cold water Push fit Soil pipes Waste and overflow pipes Guttering and downpipe MDP Medium density Degrades in sunlight E polyethylene Fusion welded Underground mains (blue) Push fit CWSC Compression HDPE High density polyethylene Degrades in sunlight Underground mains Fusion welded (black) Push fit Compression Thermoplastics Polypropyle Waste pipes Degrades in direct ne Overflow sunlight CWSC Feels slightly greasy to the touch Not solvent welded Polybutylen Cold water Push fit e Hot water Compression Central heating Not solvent welded ABS Commercial water Solvent welded Acrylonitril Waste Degrades in sunlight e Overflow Butadiene Styrene Thermosetting These are rigid plastics that can cope with high temperatures, but are non recyclable. Formica and bakelite are examples. Mass is an amount of substance. It is measured in kilograms Weight is the force of gravity pulling on a mass: 1 kg = 10N (9.81N) Weight is a force, it is measured in newton's, not kilograms. weight = mass x gravity Our weight alters if we go to the moon – as gravity is much less on the moon – but our mass stays the same. Gravity is a force of attraction between masses. Gravity is a property of mass; the bigger the mass, the bigger the gravity. On earth, gravity is 9.81N; on the moon, which is a smaller planet, it is only 1.6N. Density Solid materials of the same size and shape can have a completely different weight because their molecules are more tightly packed together. To find the density of an object, use the following formula: Heat transfer through differing materials can vary according to their density, like a heat exchanger. Dry to wet Boiler Dry to dry Warm air unit Wet to dry Radiator Wet to wet DHWC Heated molecules pass on heat to the adjoining material, which in turn heats up. Some materials are better at conducting heat than others. Eg metal (copper) is a good conductor of heat but wood is not. Relative density is when we compare the mass of material. We say: Water has a density of 1 This means that any solid or liquid with a density of more than 1 will sink, and any solid or liquid with a density of less than 1 will float. We say: Air has a density of 1 This means that any gas with a density of more than 1 will sink, and any gas with a density of less than 1 will rise. Relative density Polythene 0.90 Float Water 1.00 uPVC 1.28 Sink Aluminium 2.70 Sink Cast Iron 7.90 Sink Copper 8.90 Sink Natural gas 0.6 Rise Air 1.0 Mix Propane 1.5 Sink Butane 2.0 Sink Solid materials are made up of many molecules. How these molecules are arranged, and how they behave under certain conditions, will determine the properties of that material: Strength Hardness Malleability Ductility Elasticity Durability Thermal expansion Conductivity (thermal and electrical). Strength Tensile strength: how strong is it when stretched or pulled? Some will stretch and some will break – plastic, metal, concrete. Like all forces, it is measured in N/m2 or pascals. Strength Compressive strength: how strong is a material when it is crushed? Some will shatter, others distort. Strength Shear strength: how strong is a material when forces are opposing? Scissors, and ripping apart, are examples. Ductile Sometimes known as toughness. How much can a material be pulled, pushed or stretched without breaking? Copper is very ductile, as we bend copper tube into shape. Malleability How much can a material be compressed without fracturing? If we hammer or roll a material, will it change shape without cracking? Lead is very malleable, as it can be bossed into shape. Hardness This is the resistance of a material to bending, scratching, abrasion or cutting. Try to cut: Wood Copper LCS Diamond Specific heat capacity How much energy is required to heat something up It is the amount of heat required to raise 1kg of a substance through 10C. Specific heat values change as the temperature increases. For plumbers, it may be important to work out how much heat is needed to heat a volume of water from one temperature to another. Specific heat capacity Specific heat value x kg x temperature rise 1kg of water to rise 50C 4.186 x 1 x 5 = 20.93 KJ/kg/0C Kilojoules/kilogram/degrees centigrade PROPERTIES OF PLUMBING MATERIALS Specific heat capacity Water 4.186KJ/kg Aluminium 0.887KJ/kg Cast iron 0.554KJ/kg Zinc 0.397KJ/kg Copper 0.385KJ/kg Lead 0.125KJ/kg Mercury 0.125KJ/kg Note: water requires a high energy input to heat. How much energy is required to raise 150 litres of water from 100C to 500C? 4.186 x 150 x 40 = 25116KJ  Coefficient of linear expansion How much does a piece of material expand by when heated? In every installation, plumbers need to take into consideration the expansion of materials: when hot water flows through pipes; when the material is in the sun or in the shade. Plastic guttering expands the most out of all installations. Creaking pipework under floors is due to expansion and contraction. Coefficient of linear expansion Length of material x the temperature rise x the coefficient of expansion for that material. Plastic uPVC 0.00018 Lead 0.000029 Copper 0.000016 Steel 0.000011 How much will a 6 metre length of plastic guttering expand by, if the temperature rises by 100C? 6000mm x 10 x 0.00018 = 10.8mm Corrosion All materials will corrode over time. The amount and speed of the corrosion will depend on the material’s resistance and environment. Wet conditions Gases Dissimilar metals Acids (chemicals) Heat UV Corrosion The most common form of corrosion is rust (ferrous oxide). Rust occurs when water, iron and oxygen are together. LCS pipework – only for central heating, is unprotected where inhibitor is used. Cast iron central heating pump – only used with inhibitor. Preventing corrosion Inhibitor protects iron in central heating systems (annual check). Galvanised coating protects LCS from environment and oxygen in the water (life, if coating is not damaged). Painting cast iron guttering, downpipes and central heating pipes protects the metal from atmospheric corrosion (regular maintenance). Denso tape protects LCS pipes from external environment and underground (20 years). Corrosion Enamelling: pressed steel baths, cast iron baths and appliance casings.  Corrosion Dezincification is another form of corrosion that can occur within a plumbing and heating system. Brass (copper and zinc) components can have zinc leached out, as fresh water passes through them. It leaves the brass fitting weak and brittle, quite often covered in white powder (zinc oxide). Modern brass components are dezincification resistant and have DZR or DZ stamped on them. Corrosion Electrolytic corrosion happens where dissimilar metals are in contact with each other – through the presence of an electrolyte. In a plumbing system, there are many different metals in contact, ie you may have copper and LCS pipework, a cast iron pump, brass compression fittings, an aluminium heat exchanger etc. Because the pipes are filled with water (electrolyte), they are all in contact. So, as the water flows, it creates an electric current which dissolves the weakest metal. Corrosion Electromotive series Electrolytic corrosion: the further away metals are in Copper cathode the electromotive series, Tin the quicker the electrolytic Lead corrosion takes place. Cadmium In a hot water cylinder, we Iron install a sacrificial anode Chromium made of magnesium. For a central heating Zinc system, they can go in Aluminium the boiler. Magnesium anode Cathode DESTROYS the ANODE! Corrosion Pitting: after a solder joint is made, if flux is not cleaned off the outside of the tube and flushed out of the inside of the copper tube at the commissioning stage, the copper could be affected by: Type 1 pitting corrosion on the inside of the tube. Erosion: is the wearing away of pipes and fittings due to the flow of water or gas? Turbulence (over 3m/s flow rate) can increase erosion (hot and cold water pipework). Burrs are left on tube ends. Blue water corrosion can occur in a new system, which is allowed to stand dormant for a period while it is filled with water. Plastics: Can be effected by: Heat: Thermal movement and distortio UV: Sunlight degrading Oxygen: Degrading Light: Yellowing of plastic Chemicals: Degrading CHECK YOUR KNOWLEDGE WITH THESE QUESTIONS. 1. What is a ferrous metal? 2. What is a non ferrous metal? 3. what is a alloy? 4. Give a example of a thermoplastic? 5. What is gravity equal to? 6. What is specific heat capacity measured in? 7. What is the relative density of water? 8. What is corrosion? 9. how can you prevent corrosion? 10. What is blue water corrosion? TRAFFIC LIGHT IT: WHERE IS YOUR LEARNING AT? Red = I have not really understood the content we have studied today (write down 2 questions that you need help with) Amber = I have understood the content on Effective Questionning (write down 1 one question you need to clarify) Green = I have understood all the content (write down one example from what we have studied)