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Haryana BSEH Secondary NSQF Plumbing study materials
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Haryana BSEH Secondary NSQF Plumbing practice questions

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Question 1Trade Safety, Tools and Equipment

Before starting work in a trench for a water supply pipeline, which safety measure is most important to prevent collapse of the trench walls?

  1. Removing all warning signs around the site
  2. Entering the trench without a helper above
  3. Stacking excavated soil on the trench edge
  4. Shoring or sloping the sides of the trench Correct answer.

Explanation

Trench walls can collapse suddenly and bury a worker, so the sides must be supported by shoring, or cut back to a safe slope, before anyone enters. Excavated soil must be kept well away from the edge to reduce surcharge loading.

Question 2Trade Safety, Tools and Equipment

A plumber must cut a soil pipe in a confined, poorly ventilated basement. Which precaution is appropriate before using a solvent cement or primer?

  1. Use the cement near an open flame to speed drying
  2. Seal the basement doors and windows to keep fumes inside
  3. Work alone so no one else is exposed
  4. Ensure forced ventilation and use suitable respiratory protection Correct answer.

Explanation

Solvent cements and primers release flammable and harmful vapours, so good ventilation and appropriate respiratory protection are needed in confined spaces. Ignition sources must be kept away because the vapours are flammable.

Question 3Trade Safety, Tools and Equipment

Which personal protective equipment is specifically intended to protect the eyes while chiselling or drilling a wall during pipe installation?

  1. Leather gloves
  2. Steel-toe boots
  3. Safety goggles Correct answer.
  4. Ear plugs

Explanation

Safety goggles shield the eyes from flying chips of masonry, concrete and metal produced by chiselling and drilling. Boots, ear plugs and gloves protect other parts of the body and do not guard the eyes.

Question 4Trade Safety, Tools and Equipment

Which hand tool is the correct choice for gripping and turning a pipe or fitting tightly without crushing it?

  1. Spirit level
  2. Hacksaw
  3. Cold chisel
  4. Pipe wrench Correct answer.

Explanation

A pipe wrench has serrated jaws that grip round pipe and apply turning force for tightening or loosening fittings. A hacksaw cuts, a level checks alignment, and a chisel cuts masonry or metal.

Question 5Trade Safety, Tools and Equipment

What is the main purpose of wearing a safety helmet on a plumbing construction site?

  1. To keep the head warm in winter
  2. To protect the eyes from dust
  3. To protect the head from falling objects and knocks Correct answer.
  4. To identify the trade of the worker

Explanation

A safety helmet absorbs the impact of falling objects and protects the head from knocks against structures. Colour coding may identify roles, but protection is its primary function.

Question 6Trade Safety, Tools and Equipment

Which fire extinguisher class is used for fires involving flammable liquids such as solvent cement and paint thinner?

  1. Class B Correct answer.
  2. Class F
  3. Class D
  4. Class A

Explanation

Class B extinguishers are intended for flammable liquid fires, which include solvents, paints and thinners used in plumbing work. Class A covers ordinary combustibles, Class D covers metals and Class F covers cooking oils.

Question 7Trade Safety, Tools and Equipment

A plumber needs to measure the internal diameter of a pipe end accurately. Which measuring tool is most suitable?

  1. Steel tape
  2. Plumb bob
  3. Try square
  4. Vernier caliper Correct answer.

Explanation

A vernier caliper has jaws that measure internal diameters to a fraction of a millimetre. A tape measures lengths, a try square checks squareness, and a plumb bob checks verticality.

Question 8Trade Safety, Tools and Equipment

While lifting a heavy cast iron pipe section, which technique best reduces the risk of back injury?

  1. Bend the knees, keep the back straight and hold the load close to the body Correct answer.
  2. Bend at the waist and lift with a jerking motion
  3. Keep the legs straight and reach the load far in front
  4. Twist the trunk while lifting to move the load sideways

Explanation

Bending the knees and keeping the back straight uses the strong leg muscles and keeps the load close, which reduces strain on the spine. Jerking, reaching far forward and twisting all increase the risk of injury.

Question 9Trade Safety, Tools and Equipment

Which tool is used to cut an internal thread in a metal pipe fitting?

  1. Pipe cutter
  2. Die
  3. Tap Correct answer.
  4. Reamer

Explanation

A tap cuts an internal thread inside a hole or fitting, while a die cuts an external thread on a pipe. A reamer smooths the cut end and a pipe cutter parts the pipe.

Question 10Trade Safety, Tools and Equipment

Why should a pipe cutter be tightened gradually in small increments while rotating it around the pipe?

  1. To make the cutting wheel last longer only
  2. To increase the diameter of the pipe
  3. To warm the pipe before threading
  4. To avoid flattening or deforming the pipe end Correct answer.

Explanation

Gradual tightening lets the cutting wheel score a clean groove without crushing the pipe wall. Over-tightening in one turn deforms the pipe end and produces a poor, out-of-round face.

Question 11Trade Safety, Tools and Equipment

When using a hacksaw to cut a steel pipe, what is the correct action at the end of the cut to avoid injury?

  1. Reduce pressure and support the off-cut piece Correct answer.
  2. Remove the blade while the saw is still moving
  3. Turn the pipe rapidly by hand
  4. Increase pressure sharply to finish quickly

Explanation

As the cut nears completion the blade can catch and the off-cut can fall, so pressure should be eased and the piece supported. Sudden force or removing the blade mid-stroke can cause cuts and injury.

Question 12Trade Safety, Tools and Equipment

Which safety device should be checked on a portable electric pipe threading machine before use?

  1. The emergency stop and the guard over rotating parts Correct answer.
  2. The paint finish on the machine body
  3. The length of the power cable only
  4. The colour of the foot switch

Explanation

Rotating dies and chucks can entangle clothing and hands, so guards and the emergency stop must be functional before operation. Cosmetic details and cable length do not control the main mechanical hazards.

Question 13Trade Safety, Tools and Equipment

A plumber is working on a live water main and needs to isolate it before repair. Which action should be taken first?

  1. Place a bucket under the joint and proceed
  2. Open a nearby tap and start dismantling the joint
  3. Loosen the union nut slightly to check pressure
  4. Close the isolating valve and confirm the line is depressurised Correct answer.

Explanation

The supply must be isolated and the line confirmed depressurised before any joint is opened, otherwise hot or pressurised water can cause scalding or injury. Opening a joint under pressure is dangerous.

Question 14Trade Safety, Tools and Equipment

What is the correct way to store a solvent cement container after use on site?

  1. Leave it open near the work area for quick reuse
  2. Place it in direct sunlight to dry out
  3. Store it beside a gas cylinder to save space
  4. Close the lid tightly and keep it in a cool, ventilated place away from ignition sources Correct answer.

Explanation

Solvent cement is flammable and volatile, so a tightly closed container stored cool, ventilated and away from ignition sources prevents fire and vapour build-up. Leaving it open or near heat increases the hazard.

Question 15Trade Safety, Tools and Equipment

A plumber is choosing a ladder to reach a high wall for pipe bracket fixing. Which practice is correct?

  1. Rest the ladder on loose bricks to gain extra height
  2. Carry the ladder while tools are balanced on the top rung
  3. Set the ladder on firm level ground at the recommended angle and secure the top Correct answer.
  4. Stand on the top two rungs to reach higher

Explanation

A ladder must stand on firm level ground at the correct angle, and securing the top prevents slipping. Improvised supports, standing on the top rungs and balancing tools all cause falls.

Question 16Trade Safety, Tools and Equipment

Which tool is best suited for checking that a newly installed vertical soil stack is truly vertical?

  1. Vernier caliper
  2. Plumb bob Correct answer.
  3. Torque wrench
  4. Hacksaw

Explanation

A plumb bob hangs a true vertical line, so the stack is compared against the string to confirm alignment. Calipers measure small dimensions, a torque wrench tightens fasteners, and a hacksaw cuts.

Question 17Trade Safety, Tools and Equipment

Two workers must move a long pipe through a narrow corridor. Which coordination practice best reduces the risk of injury?

  1. Agree on signals and lift together with one person directing the move Correct answer.
  2. Each worker moves at their own pace without talking
  3. Drag the pipe along the floor to avoid lifting
  4. One worker carries the whole load while the other walks ahead

Explanation

Coordinated lifting with agreed signals keeps the load balanced and prevents sudden strain or crushing when passing through confined spaces. Independent movement or dragging causes loss of control.

Question 18Trade Safety, Tools and Equipment

During a pressure test of a newly installed pipeline, a joint begins to weep. What is the safest immediate response?

  1. Continue the test and record the leak for later
  2. Apply sealant over the leak without reducing pressure
  3. Tighten the joint while it is still under full pressure
  4. Depressurise the line, then repair the joint before retesting Correct answer.

Explanation

A pressurised leak can suddenly fail and cause injury, so the line must be depressurised before the joint is repaired and the test repeated. Working on a live joint or smearing sealant over a leak is unsafe and ineffective.

Question 19Trade Safety, Tools and Equipment

A plumber finds the guard missing from a bench grinder used to sharpen chisels. What is the correct course of action?

  1. Use the grinder slowly without the guard
  2. Hold the chisel with one hand and cover the wheel with a cloth
  3. Wear gloves and use the grinder as normal
  4. Do not use the grinder until the guard is refitted Correct answer.

Explanation

A grinder guard contains fragments if the wheel bursts and prevents contact with the rotating wheel, so the machine must be taken out of use until it is refitted. Gloves or cloths cannot replace a guard and can snag on the wheel.

Question 20Trade Safety, Tools and Equipment

A plumber is about to use a gas welding torch to braze a copper joint in a workshop corner. Which combination of precautions is most appropriate before striking the flame?

  1. Wear cotton gloves and a face shield only, since brazing copper does not produce hot sparks or molten flux
  2. Point the torch tip towards the wall so the flame is shielded and bystanders cannot see the spark
  3. Check the hoses and regulator connections for leaks with soap solution, clear combustible material from the area, and keep a suitable fire extinguisher within reach Correct answer.
  4. Open the acetylene cylinder valve fully and leave the oxygen cylinder key in place so the flame can be adjusted quickly

Explanation

Before any flame work, the fuel and oxygen hoses, regulators and connections must be leak-tested with soapy water, never with a flame, and all combustible material must be removed from the zone. A fire extinguisher of the correct class must be kept immediately available because brazing throws sparks and hot flux. These checks address the main ignition and leak hazards of oxy-fuel equipment.

Question 21Plumbing Materials, Pipes and Fittings

Which material is most commonly used for making soil, waste and rainwater pipes in Indian buildings because it resists corrosion and is light in weight?

  1. Copper
  2. Galvanised steel
  3. PVC (polyvinyl chloride) Correct answer.
  4. Cast iron

Explanation

PVC is a rigid thermoplastic that resists acids, alkalis and soil chemicals, is light in weight and easy to joint with solvent cement, so it is the standard choice for soil, waste and rainwater lines. Cast iron, steel and copper are used for water supply or special duties but are heavier and costlier.

Question 22Plumbing Materials, Pipes and Fittings

A plumber needs a fitting to join two lengths of GI pipe in a straight line so that the joint can be opened later for maintenance. Which fitting is most suitable?

  1. Bend
  2. Elbow
  3. Union Correct answer.
  4. Reducer

Explanation

A union has three parts (two end nuts and a central body) and allows the joint to be unscrewed and remade without cutting the pipe, which is ideal where future dismantling is required. An elbow or bend changes direction, and a reducer changes diameter, so neither serves this purpose.

Question 23Plumbing Materials, Pipes and Fittings

Which standard designation correctly describes a GI pipe of 25 mm nominal bore?

  1. 20 mm GI pipe
  2. 25 mm GI pipe Correct answer.
  3. 32 mm GI pipe
  4. 15 mm GI pipe

Explanation

Nominal bore (NB) is the standard designation of a pipe's approximate internal diameter, so a 25 mm NB pipe is ordered and described as a 25 mm GI pipe. The designation is a nominal size and not the exact measured outside diameter.

Question 24Plumbing Materials, Pipes and Fittings

Which type of valve is installed at the entry of a water supply line to a building so that the entire supply can be shut off for repairs?

  1. Float valve
  2. Stop cock Correct answer.
  3. Air release valve
  4. Bib cock

Explanation

A stop cock is a screw-down valve fitted at the service entry or on a branch to isolate the supply completely during repairs. A bib cock is a tap for drawing water, a float valve controls tank filling, and an air release valve removes trapped air.

Question 25Plumbing Materials, Pipes and Fittings

Solvent cement jointing is the standard method of joining which of the following pipes?

  1. GI pipes
  2. Cast iron soil pipes
  3. PVC pipes Correct answer.
  4. Copper pipes

Explanation

PVC is a thermoplastic, so the solvent cement softens the surfaces of the pipe and socket and fuses them into a single leak-proof joint as it sets. Metal pipes such as GI, cast iron and copper cannot be joined this way and need threaded, flanged or soldered joints.

Question 26Plumbing Materials, Pipes and Fittings

What is the main purpose of a trap fitted below a wash basin?

  1. To hold a water seal that prevents foul gases from entering the room Correct answer.
  2. To increase the water pressure at the tap
  3. To filter out sand and grit from the water
  4. To reduce the noise of flowing water

Explanation

A trap retains a small body of water called the water seal, which blocks sewer gases and odours from passing back through the fixture into the room. The depth and retention of this seal are the basis of sanitary design.

Question 27Plumbing Materials, Pipes and Fittings

Which pipe material is preferred for carrying hot water in a building because it withstands high temperature without softening?

  1. Polyethylene
  2. Unplasticised PVC
  3. Copper Correct answer.
  4. Rigid PVC

Explanation

Copper has a high melting point and retains strength at domestic hot water temperatures, so it is widely used for hot water lines. Ordinary PVC and polyethylene soften at much lower temperatures and are limited to cold water or drainage duty.

Question 28Plumbing Materials, Pipes and Fittings

A plumber must cut an internal thread on a GI pipe end before fitting a socket. Which tool is used for this job?

  1. Pipe cutter
  2. Flaring tool
  3. Pipe wrench
  4. Die and stock Correct answer.

Explanation

A die held in a stock is rotated over the pipe end to cut an external (male) thread that matches the internal thread of the socket or fitting. A pipe cutter only severs the pipe, a pipe wrench only turns fittings, and a flaring tool is for flare joints on soft tubing.

Question 29Plumbing Materials, Pipes and Fittings

A 15 mm GI pipe is to be joined to a 20 mm GI pipe in a straight run. Which fitting should be used?

  1. Elbow
  2. Cap
  3. Coupling
  4. Reducer socket Correct answer.

Explanation

A reducer socket has one end threaded for the larger pipe and the other for the smaller pipe, so it makes a straight transition between two different nominal bores. A plain coupling joins equal sizes, an elbow changes direction, and a cap closes off a pipe end.

Question 30Plumbing Materials, Pipes and Fittings

Which property makes asbestos cement pipes unsuitable for modern plumbing installations in India?

  1. They cannot carry water under gravity
  2. They are very heavy and cannot be laid underground
  3. Their fibres pose a serious health hazard when cut or handled Correct answer.
  4. They dissolve completely in soft water

Explanation

Asbestos cement pipes were once used for drainage and water mains, but the asbestos fibres released during cutting, drilling and demolition are a recognised health hazard, so their use has been discontinued. They are actually light, durable and able to carry water by gravity.

Question 31Plumbing Materials, Pipes and Fittings

In a multi-storey building, a vertical soil stack is fitted with a vent pipe continued above the roof. What is the main function of this vent?

  1. To drain rainwater from the roof
  2. To admit fresh air for the occupants
  3. To allow easy inspection of the stack
  4. To balance air pressure in the stack and protect trap seals from siphonage Correct answer.

Explanation

The vent admits air into the stack so that the pressure in the pipe stays close to atmospheric when a large flow passes. Without it, a partial vacuum can siphon water out of fixture traps and break the water seal, allowing foul gas into the building.

Question 32Plumbing Materials, Pipes and Fittings

The water seal of a trap is 40 mm deep. Which condition will most likely break this seal?

  1. Self-siphonage caused by a long, steep fixture drain Correct answer.
  2. Fitting the trap close to the fixture outlet
  3. Use of a bottle trap instead of a P-trap
  4. Slow drainage of a wash basin

Explanation

A long, steep or poorly vented fixture drain can pull a partial vacuum behind the flowing water and siphon the trap seal away, which is called self-siphonage. Trap depth, trap type and proximity to the fixture affect seal retention but do not by themselves create a siphon.

Question 33Plumbing Materials, Pipes and Fittings

Which of the following is the correct reason for using a lead caulked joint on traditional cast iron soil pipe?

  1. To provide an electrical earth connection
  2. To reduce the weight of the pipe assembly
  3. To make the joint flexible and watertight by packing and caulking lead in the socket Correct answer.
  4. To allow the joint to be unscrewed during maintenance

Explanation

In a lead caulked joint, the annular space between the spigot and socket is packed with yarn and then filled with molten lead, which is caulked tight to give a flexible, watertight seal. It is a permanent joint and cannot be unscrewed.

Question 34Plumbing Materials, Pipes and Fittings

A plumber is selecting a float valve for a rooftop storage tank. Which fitting should be installed at the tank inlet so that the supply stops automatically when the tank is full?

  1. Non-return valve
  2. Gate valve
  3. Pressure reducing valve
  4. Ball float valve Correct answer.

Explanation

A ball float valve carries a hollow float on a lever arm; as the water level rises the float lifts and the lever closes the inlet, stopping the supply automatically at the set level. A gate valve needs manual operation, a pressure reducing valve controls pressure, and a non-return valve prevents backflow.

Question 35Plumbing Materials, Pipes and Fittings

Which of the following statements about the nominal bore (NB) of a pipe is correct?

  1. It is the length of one standard pipe length
  2. It is the exact outside diameter of the pipe
  3. It is an approximate internal diameter used as a standard size designation Correct answer.
  4. It is the exact wall thickness of the pipe

Explanation

Nominal bore is a standard size label that approximates the internal diameter of the pipe; the actual inside and outside diameters vary with the pipe schedule and wall thickness. It is not an exact dimension and is not related to pipe length.

Question 36Plumbing Materials, Pipes and Fittings

Which fitting is used to connect a branch pipe at 90 degrees to a main run of GI pipe while keeping the main run continuous?

  1. Cross
  2. Tee Correct answer.
  3. Nipple
  4. Socket

Explanation

A tee has a straight run through it and a side outlet at 90 degrees, so a branch can be taken off a continuous main without cutting it into two separate lines. A cross gives two opposite branches, a socket is a straight coupling, and a nipple is a short threaded piece.

Question 37Plumbing Materials, Pipes and Fittings

A plumber finds that a copper tube joint leaks at a soldered capillary fitting. Which cause is most consistent with a joint that was heated too quickly with a large flame?

  1. The solder used was of the lead-free type
  2. The flux was burnt before the solder could flow into the gap Correct answer.
  3. The fitting was cleaned with emery cloth
  4. The tube was cut with a hacksaw and not reamed

Explanation

Overheating burns the flux, so it can no longer dissolve oxides and draw solder into the capillary gap, leaving voids that leak. Cleaning the tube and fitting and applying gentle, even heat are the correct practices for a sound joint.

Question 38Plumbing Materials, Pipes and Fittings

Which type of pipe is best suited for laying a buried water supply main across a road where external loads are heavy?

  1. CPVC pipe
  2. Ductile iron pipe Correct answer.
  3. UPVC pressure pipe
  4. GI pipe

Explanation

Ductile iron has high strength and toughness, so it resists heavy external loads and traffic vibration when buried under a road. UPVC, GI and CPVC are lighter-walled materials better suited to normal buried or internal service with adequate bedding and protection.

Question 39Plumbing Materials, Pipes and Fittings

A wash basin trap has a seal depth of 75 mm. What is the practical consequence of this seal depth?

  1. The trap will act as a grease trap
  2. The seal is deeper than needed and increases the risk of foul odour from the trap body Correct answer.
  3. The trap will drain faster than a 50 mm seal trap
  4. The fixture will not drain at all

Explanation

A seal deeper than about 50 mm is unnecessary for a wash basin and holds a large body of stagnant water in the trap, which can itself become foul; standard practice limits seal depth to about 50 mm. Drainage speed is governed mainly by pipe size and fall, not seal depth.

Question 40Plumbing Materials, Pipes and Fittings

Which statement correctly distinguishes a coupling from a union in a GI pipe installation?

  1. A coupling is used only on PVC, whereas a union is used only on GI
  2. A coupling can be opened without disturbing the pipes, whereas a union cannot
  3. A coupling is a permanent screwed joint, whereas a union can be dismantled without cutting or unscrewing the pipe lengths Correct answer.
  4. A coupling changes pipe direction, whereas a union changes pipe size

Explanation

A coupling is a simple socket screwed onto two pipe ends, so dismantling it means unscrewing one of the pipes. A union has a central nut that can be loosened to separate the joint without moving either pipe, which is why it is placed where future maintenance access is needed.

Question 41Plumbing Materials, Pipes and Fittings

Which factor most directly decides the class or pressure rating of a UPVC water supply pipe?

  1. The wall thickness relative to the diameter Correct answer.
  2. The length of each pipe section
  3. The type of solvent cement used
  4. The colour of the pipe

Explanation

The pressure rating of a thermoplastic pressure pipe depends on the ratio of wall thickness to diameter: a thicker wall for the same diameter gives a higher class and working pressure. Colour, length and cement type do not determine the pressure rating.

Question 42Plumbing Materials, Pipes and Fittings

In a building drainage system, why are inspection chambers and rodding eyes provided at intervals along the drain?

  1. To collect rainwater separately from the soil drain
  2. To support the drain pipes in the trench
  3. To increase the velocity of flow in the drain
  4. To allow access for clearing blockages and inspecting the drain condition Correct answer.

Explanation

Inspection chambers and rodding eyes give access points where a rod or drain-cleaning tool can be inserted to remove obstructions and where the drain can be visually examined. They are placed at changes of direction, junctions and intervals along long runs for this maintenance purpose.

Question 43Plumbing Materials, Pipes and Fittings

A plumber must join a 32 mm GI pipe to a 32 mm copper pipe where the joint may need to be opened for maintenance. Which arrangement is technically sound?

  1. Weld the copper pipe directly to the GI pipe
  2. Solvent cement the two pipes directly together
  3. Thread the copper pipe and screw it into a GI socket
  4. Use a dielectric union or a flanged adaptor with an insulating gasket Correct answer.

Explanation

Dissimilar metals in contact with water form a galvanic couple, and the less noble metal corrodes; an insulating gasket or dielectric union breaks the electrical path and also allows the joint to be dismantled. Direct threading or welding of copper to GI is impractical and would not stop galvanic corrosion.

Question 44Plumbing Materials, Pipes and Fittings

A vertical stack serving several floors discharges a large flow. Which combination best protects the trap seals on the lower floors?

  1. Providing a vent pipe and limiting the length of the branch drains Correct answer.
  2. Reducing the stack diameter and removing the vent
  3. Increasing the branch gradient sharply and fitting shallow traps
  4. Fitting a grease trap on each branch

Explanation

Adequate venting keeps stack pressure close to atmospheric, and short branch drains limit the suction developed behind the flow, so trap seals stay intact. Reducing the stack, steepening branches or using shallow traps all increase the risk of siphonage and seal loss.

Question 45Plumbing Materials, Pipes and Fittings

Why is a non-return valve fitted on the delivery line of a pump that lifts water to an overhead tank?

  1. To reduce the pump speed automatically
  2. To release air trapped in the delivery pipe
  3. To measure the quantity of water delivered
  4. To prevent water from flowing back through the pump when it stops Correct answer.

Explanation

When the pump stops, the column of water in the delivery pipe tends to run back; a non-return valve closes against this reverse flow and protects the pump and priming. Speed control, flow measurement and air release are done by other devices.

Question 46Plumbing Materials, Pipes and Fittings

A plumber needs to join two lengths of 25 mm high-density polyethylene (HDPE) water main in a trench. Which jointing method is most suitable for this buried pipeline?

  1. Butt fusion using a heated plate Correct answer.
  2. Soldering with lead-free solder
  3. Solvent cementing with PVC cement
  4. Threading with a die and fitting a socket

Explanation

HDPE is a thermoplastic that cannot be threaded or solvent-cemented reliably, so the standard field method for joining buried HDPE mains is heat butt fusion, which melts both pipe ends and fuses them into a continuous joint as strong as the pipe wall.

Question 47Plumbing Materials, Pipes and Fittings

A plumber is installing a drainage line and needs a fitting that allows the pipe to change direction by 45 degrees in a soil stack run. Which fitting is appropriate?

  1. A 45 degree bend Correct answer.
  2. A straight coupling
  3. A concentric reducer
  4. A tee with a 90 degree branch

Explanation

A bend is a drainage fitting designed to change the direction of the pipeline, and a 45 degree bend gives a gentler change of direction than a 90 degree bend, which reduces the risk of solids settling and blockage in the drain.

Question 48Plumbing Materials, Pipes and Fittings

A plumber is laying a UPVC soil pipe and wants to allow for thermal expansion between two fixed supports. Which provision is most appropriate?

  1. Use a longer length of pipe and avoid any joints
  2. Insert a socket-and-spigot joint left partly unseated with a gap so the spigot can slide Correct answer.
  3. Weld the pipe ends rigidly to the supports
  4. Clamp the pipe tightly at every support to prevent movement

Explanation

UPVC expands and contracts with temperature change, so the pipe run must be allowed to move. Leaving a controlled expansion gap in a push-fit socket joint, or fitting a dedicated expansion joint, lets the spigot slide inside the socket without stressing the pipe or the supports.

Question 49Plumbing Materials, Pipes and Fittings

A plumber is selecting a valve for a cold water distribution line where the flow must be shut off quickly and the valve should give a clear visual indication of whether it is open or closed. Which valve type best meets this requirement?

  1. A gate valve
  2. A float valve
  3. A ball valve with a lever handle Correct answer.
  4. A pressure reducing valve

Explanation

A ball valve uses a quarter-turn lever that shows at a glance whether the valve is open or closed, and it gives quick shut-off with low resistance to flow when fully open, which suits a cold water distribution line.

Question 50Plumbing Materials, Pipes and Fittings

A plumber is connecting a vitrified clay (stoneware) drain pipe to a PVC inspection chamber. Which property of vitrified clay pipe most influences how the joint must be made?

  1. Its smooth internal bore
  2. Its low thermal conductivity
  3. Its high resistance to chemical attack
  4. Its rigid, brittle nature with no flexibility at the joint Correct answer.

Explanation

Vitrified clay is rigid and brittle, so it cannot absorb differential settlement or movement the way a flexible plastic pipe can. Joints to a PVC chamber must therefore be made with a flexible adaptor or coupling that accommodates slight movement and prevents cracking at the connection.