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RBSE SS Voc Plumbing practice questions

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Question 1Plumbing Tools, Materials and Safety Practices

Which material is most commonly specified for buried sanitary drainage pipe because it resists corrosion and root intrusion at joints?

  1. Galvanized steel pipe
  2. Copper Type M tube
  3. PVC Schedule 40 pipe Correct answer.
  4. Cast iron soil pipe

Explanation

PVC is widely used for underground sanitary drainage because it resists corrosion in soil, is lightweight, and solvent-welded joints form a continuous seal that resists root intrusion. Cast iron and steel corrode over time, and copper is normally reserved for supply lines and above-ground drainage where specified.

Question 2Plumbing Tools, Materials and Safety Practices

A plumber must cut a 4-inch cast iron soil pipe in a trench. Which tool is the standard choice for a clean, square cut?

  1. Hacksaw with a 24-tooth blade
  2. Reciprocating saw with a wood blade
  3. Snap cutter
  4. Chain soil pipe cutter Correct answer.

Explanation

A chain soil pipe cutter uses hardened wheels and chain pressure to score and snap cast iron cleanly and squarely, which is the standard field method. A snap cutter is for plastic or copper, and a wood blade will not cut cast iron.

Question 3Plumbing Tools, Materials and Safety Practices

Before entering a below-grade vault suspected of containing sewer gas, what is the minimum required action?

  1. Leave the access hatch open and enter alone
  2. Test the atmosphere and provide ventilation and an attendant Correct answer.
  3. Enter quickly to finish before gas builds up
  4. Wear a dust mask and proceed

Explanation

Confined spaces must be tested for oxygen and hazardous gases before entry, ventilated, and monitored by an attendant outside. Sewer gas can contain hydrogen sulfide and methane, which can be immediately dangerous to life and health.

Question 4Plumbing Tools, Materials and Safety Practices

Which fitting is used to connect a branch drain into a horizontal main drain while directing flow in the direction of drainage?

  1. Street 45 elbow
  2. Sanitary tee
  3. Wye (Y) branch Correct answer.
  4. Test tee

Explanation

A wye fitting introduces a branch at a shallow angle so flow sweeps into the main in the direction of drainage, reducing clogging. A sanitary tee is intended for vertical-to-horizontal changes, and a test tee is for testing, not branching.

Question 5Plumbing Tools, Materials and Safety Practices

What is the primary purpose of a trap primer connected to a floor drain?

  1. To filter debris from the drain
  2. To keep the trap seal from evaporating Correct answer.
  3. To increase drain flow rate
  4. To vent the drain line

Explanation

A trap primer delivers a small amount of water to a floor drain trap so the water seal does not evaporate during long dry periods. Without the seal, sewer gas can enter the building.

Question 6Plumbing Tools, Materials and Safety Practices

Which PPE is specifically required when solvent-welding PVC pipe with primer and cement?

  1. Chemical-resistant gloves and eye protection Correct answer.
  2. Leather welding gloves
  3. Hearing protection
  4. Steel-toed boots only

Explanation

PVC primer and cement contain volatile solvents that irritate skin and eyes, so chemical-resistant gloves and safety glasses are the appropriate protection. Leather welding gloves are for heat, not chemicals.

Question 7Plumbing Tools, Materials and Safety Practices

A plumber is setting a 3-inch PVC drain line to maintain a standard slope. What fall per foot of run is typically specified for a 3-inch drain?

  1. 1/8 inch per foot Correct answer.
  2. 1/4 inch per foot
  3. 1/16 inch per foot
  4. 1/2 inch per foot

Explanation

Standard practice calls for 1/4 inch per foot on pipe 2 inches and smaller and 1/8 inch per foot on 3-inch and larger drains. A 3-inch line therefore uses 1/8 inch per foot to carry solids while keeping the trench grade reasonable.

Question 8Plumbing Tools, Materials and Safety Practices

Which tool is used to tighten a compression nut on a supply stop without crushing the fitting?

  1. Chain wrench
  2. Adjustable wrench Correct answer.
  3. Basin wrench
  4. Pipe wrench

Explanation

An adjustable wrench gives controlled jaw pressure that tightens a compression nut without crushing thin brass fittings. A pipe wrench has aggressive teeth that mar chrome, and a chain wrench is for large pipe.

Question 9Plumbing Tools, Materials and Safety Practices

A plumber needs to join a 2-inch copper supply line to a 2-inch PEX line. Which fitting type is appropriate?

  1. Push-to-connect transition fitting rated for both materials Correct answer.
  2. Solder-only copper coupling
  3. Threaded galvanized coupling
  4. Barbed insert fitting with no clamp

Explanation

Push-to-connect transition fittings are listed for joining copper to PEX and provide a mechanical seal on both materials. Solder couplings join copper only, and barbed insert fittings need a clamp and are used within PEX systems.

Question 10Plumbing Tools, Materials and Safety Practices

What is the purpose of dielectric unions when connecting copper pipe to steel pipe?

  1. To provide a test port
  2. To prevent galvanic corrosion between dissimilar metals Correct answer.
  3. To increase flow velocity
  4. To allow thermal expansion

Explanation

Dissimilar metals in contact with an electrolyte create a galvanic cell that corrodes the less noble metal. A dielectric union inserts an insulating barrier to break the electrical path and prevent that corrosion.

Question 11Plumbing Tools, Materials and Safety Practices

A plumber is installing a water heater and must provide a relief valve discharge pipe. Which installation is correct?

  1. Discharge pipe reduced to 1/2 inch to save space
  2. Discharge pipe routed upward to a floor drain
  3. Discharge pipe terminating 6 inches above a floor drain with no threads at the end Correct answer.
  4. Discharge pipe capped to prevent leaks

Explanation

The relief valve discharge must terminate through an air gap above a drain with an unthreaded end so it cannot be capped and so backflow is prevented. The pipe must not be reduced, trapped, or run uphill.

Question 12Plumbing Tools, Materials and Safety Practices

Which condition indicates that a PVC solvent-welded joint was made incorrectly?

  1. A uniform bead of cement around the joint
  2. Visible gaps or a dry joint at the socket Correct answer.
  3. Joint set within 30 seconds
  4. Pipe fully inserted to the shoulder

Explanation

A proper solvent weld shows a continuous bead of softened cement and full insertion. Visible gaps or a dry socket indicate insufficient cement or movement during cure, which will leak under pressure.

Question 13Plumbing Tools, Materials and Safety Practices

A crew is excavating a 5-foot-deep trench in unstable soil. Which safety measure applies?

  1. Stacking spoil at the trench edge
  2. Using a ladder only for exits deeper than 8 feet
  3. Sloping or shoring the trench walls Correct answer.
  4. Allowing workers to enter without protection if the trench is short

Explanation

Trenches 5 feet or deeper require protective systems such as sloping, shoring, or shielding unless the excavation is entirely in stable rock. Spoil should be kept back from the edge, and a ladder is required for access at 4 feet.

Question 14Plumbing Tools, Materials and Safety Practices

What does the term "developed length" refer to when sizing a drainage system?

  1. The vertical rise of the stack
  2. The horizontal distance only
  3. The total length of pipe measured along the centerline including fittings Correct answer.
  4. The distance to the property line

Explanation

Developed length is measured along the centerline of the pipe run, including the equivalent length added by fittings. It is used with fixture units to determine proper pipe sizing and venting.

Question 15Plumbing Tools, Materials and Safety Practices

Which test method is used to verify the integrity of a newly installed DWV system before closing walls?

  1. Visual inspection only
  2. Flow test with a garden hose
  3. Air test at 5 psi or water test with a 10-foot head Correct answer.
  4. Smoke test only

Explanation

DWV systems are commonly tested with a water test filling the system to a 10-foot head or an air test at about 5 psi held for a specified period. These tests reveal leaks that a visual check or simple flow test would miss.

Question 16Plumbing Tools, Materials and Safety Practices

A plumber is selecting a pipe material for a hot water heating loop that must resist oxygen diffusion. Which material is designed for this application?

  1. Standard PEX
  2. PVC Schedule 40
  3. PEX with an oxygen barrier Correct answer.
  4. Galvanized steel

Explanation

PEX with an oxygen barrier layer is manufactured for hydronic heating loops to prevent oxygen from diffusing through the wall and corroding ferrous components. Standard PEX allows oxygen passage, and PVC is not rated for hot hydronic service.

Question 17Plumbing Tools, Materials and Safety Practices

What is the function of a cleanout fitting in a drainage system?

  1. To provide access for clearing blockages Correct answer.
  2. To vent the stack
  3. To regulate water pressure
  4. To trap debris

Explanation

Cleanouts provide a removable plug giving access to the drain for rodding or jetting blockages. They are required at the base of stacks and at changes in direction so maintenance can be performed without cutting pipe.

Question 18Plumbing Tools, Materials and Safety Practices

A plumber must install a water service line under a driveway. Which practice protects the pipe from frost and traffic loads?

  1. Bury it at the minimum depth only
  2. Install below frost depth with proper bedding and, where required, a sleeve or casing Correct answer.
  3. Lay it directly on native soil without bedding
  4. Wrap it in plastic only

Explanation

Service lines must be placed below the local frost depth and bedded in suitable material to prevent point loading and settlement. Where crossing under driveways, a sleeve or casing may be required to protect against loads and allow replacement.

Question 19Plumbing Tools, Materials and Safety Practices

Which safety hazard is associated with lead-based solder used on older potable water lines?

  1. Increased water pressure
  2. Lead leaching into drinking water Correct answer.
  3. Frozen pipes
  4. Electrical shock

Explanation

Lead-based solder can leach lead into drinking water, posing a health hazard, which is why lead-free solder is now required for potable lines. The other options are unrelated to solder composition.

Question 20Plumbing Tools, Materials and Safety Practices

A plumber is installing a gas water heater in a garage. Which requirement applies to protect the ignition source?

  1. Install the heater directly on the floor
  2. Seal the combustion air openings
  3. Elevate the ignition source 18 inches above the floor Correct answer.
  4. Install a flexible connector through a wall

Explanation

In garages, water heaters with an ignition source must be elevated so the pilot or igniter is at least 18 inches above the floor to reduce the risk of igniting gasoline vapors, which are heavier than air. Flexible connectors must not pass through walls.

Question 21Plumbing Tools, Materials and Safety Practices

A plumber is sizing a vent for a fixture drain. What is the purpose of the vent's developed length limit?

  1. To control water pressure
  2. To ensure the vent can admit enough air to protect the trap seal Correct answer.
  3. To determine pipe color
  4. To limit the total fixture units

Explanation

Vent length and size limits ensure that the vent can supply air quickly enough to prevent trap siphonage when the fixture drains. Exceeding the developed length limit can break the trap seal.

Question 22Plumbing Tools, Materials and Safety Practices

A plumber discovers a leaking joint on a pressurized copper line inside a finished wall. What is the best first step?

  1. Increase pressure to reseat the joint
  2. Shut off the water, drain the line, and repair the joint properly Correct answer.
  3. Wrap the joint with tape
  4. Apply epoxy putty and close the wall

Explanation

Isolating and draining the line stops damage and allows a proper repair, such as cutting out and re-soldering or replacing the section. Temporary patches inside a finished wall risk hidden water damage and repeat failure.

Question 23Plumbing Tools, Materials and Safety Practices

What is the primary reason for using a trap arm with a proper fall and length limit?

  1. To reduce water usage
  2. To allow the trap to dry out
  3. To increase drain noise
  4. To prevent trap siphonage and backflow of sewer gas Correct answer.

Explanation

The trap arm slope and length limits ensure that air can enter behind the waste flow, preventing siphonage of the trap seal. A siphoned trap allows sewer gas to enter the building.

Question 24Plumbing Tools, Materials and Safety Practices

A plumber is choosing pipe insulation for a chilled water line to prevent condensation. Which property is most important?

  1. Flame spread rating only
  2. Color
  3. Closed-cell structure with a vapor barrier Correct answer.
  4. High compressive strength only

Explanation

Closed-cell insulation with a sealed vapor barrier limits moisture migration to the cold surface, preventing condensation and mold. Open-cell materials can absorb water vapor and lose insulating value.

Question 25Plumbing Tools, Materials and Safety Practices

A plumber must connect a fixture drain to a stack where the horizontal branch runs a long distance. Which fitting arrangement best preserves the trap seal?

  1. A sanitary tee installed horizontally
  2. A vent tee with no vent
  3. A double sanitary tee
  4. A wye plus a 45-degree elbow Correct answer.

Explanation

A wye plus a 45-degree elbow provides a smooth, sweeping transition that maintains flow and allows venting to protect the trap seal. A horizontal sanitary tee or unvented vent tee can promote siphonage and clogging.

Question 26Plumbing Tools, Materials and Safety Practices

When using a hand auger to clear a clogged lavatory trap, which practice helps prevent damage to the fixture or the cable?

  1. Apply steady pressure while rotating the cable clockwise Correct answer.
  2. Remove the trap and feed the cable directly into the drain
  3. Force the cable through the clog with rapid back-and-forth strokes
  4. Run the auger at high speed with a drill adapter

Explanation

A hand auger is designed to be turned clockwise with steady pressure so the cutting head engages the clog and pulls it back. Rapid back-and-forth strokes can kink the cable or scratch the fixture surface, and removing the trap is unnecessary for a trap clog. Using a drill adapter at high speed risks binding and damaging the cable or fixture.

Question 27Plumbing Tools, Materials and Safety Practices

Which safety practice is required before using a power drain-cleaning machine with a cable that may contact electrical wiring or a metal fixture?

  1. Wear rubber gloves and stand on a dry wooden board
  2. Ensure the machine is properly grounded and use a GFCI-protected outlet Correct answer.
  3. Operate the machine only with the cable fully extended
  4. Disconnect the machine's ground prong to avoid shock

Explanation

Power drain-cleaning machines must be grounded and plugged into a GFCI-protected circuit to reduce the risk of electric shock, especially when the cable may contact metal or wiring. Rubber gloves and a wooden board do not replace proper grounding, and removing the ground prong defeats the safety feature. The cable should not be fully extended during operation because that reduces control.

Question 28Plumbing Tools, Materials and Safety Practices

A plumber is selecting a pipe wrench for a 1-inch black iron gas line. Which feature is most important for safe and effective use?

  1. A wrench with a ratcheting mechanism for speed
  2. A wrench with a longer handle to increase leverage
  3. A wrench with a jaw capacity that fits the pipe and teeth in good condition Correct answer.
  4. A wrench with an aluminum handle for lighter weight

Explanation

A pipe wrench must have a jaw capacity that matches the pipe size and sharp teeth that bite into the pipe without slipping. Worn teeth or an undersized jaw can slip and cause injury or damage to the fitting. Handle material, handle length beyond the standard design, and ratcheting features are secondary to proper jaw fit and tooth condition.

Question 29Plumbing Tools, Materials and Safety Practices

When joining two lengths of PEX tubing with a crimp ring and fitting, which practice helps ensure a leak-free connection?

  1. Crimp the ring twice to ensure it is tight
  2. Leave the ring loose until after the system is pressurized
  3. Use a utility knife to bevel the tubing end before inserting the fitting
  4. Cut the tubing square and slide the ring to the correct distance from the end before crimping Correct answer.

Explanation

A square cut and correct ring placement are essential for a proper crimp on PEX. The ring must be positioned at the specified distance from the tubing end and crimped once with the correct tool. Double-crimping can damage the ring, beveling with a knife can create an uneven edge, and leaving the ring loose until pressurization will not create a seal.

Question 30Plumbing Tools, Materials and Safety Practices

A plumber is preparing to solder a copper joint in a confined space. Which combination of practices best reduces the risk of fire and exposure to flux fumes?

  1. Solder quickly to minimize the time the torch is lit
  2. Wear a dust mask and keep a bucket of water nearby
  3. Open a window and rely on natural air movement
  4. Use a fire watch, shield nearby combustibles, and provide mechanical ventilation Correct answer.

Explanation

Soldering in a confined space requires a fire watch, shielding of combustibles, and mechanical ventilation to remove flux fumes and reduce fire risk. Working quickly does not address fire hazards or fume exposure, and a dust mask does not filter flux fumes. Natural ventilation may be insufficient in a confined space, so mechanical ventilation is needed.

Question 31Water Supply Systems and Pipe Fitting

In a domestic cold water supply, what is the main purpose of the float-operated valve (ball valve) inside a cistern?

  1. To isolate the cistern for maintenance by manual turning
  2. To shut off the incoming supply once the cistern reaches its set water level Correct answer.
  3. To prevent backflow from the cistern into the mains pipe
  4. To release trapped air from the rising main during filling

Explanation

A float valve uses a buoyant float linked to a plunger or diaphragm; as water rises the float lifts and closes the inlet at the set level, then reopens as the level falls on draw-off. This maintains a stored reserve and controls refilling automatically. Air release and manual isolation are handled by separate fittings.

Question 32Water Supply Systems and Pipe Fitting

Which pipe material is most commonly specified for buried cold water service mains because it resists corrosion and is joined by solvent cement or push-fit fittings?

  1. uPVC Correct answer.
  2. Cast iron
  3. Galvanised mild steel
  4. Copper

Explanation

uPVC is widely used for buried cold water service pipes because it is corrosion resistant, light, and cheap, and joints are made with solvent cement or push-fit seals. It is limited to cold water because heat softens it. The other materials are used but are not joined by solvent cement.

Question 33Water Supply Systems and Pipe Fitting

What does the term 'static head' refer to in a cold water supply system?

  1. The volume of water stored in the roof tank
  2. The rate at which water discharges from a tap
  3. The pressure loss caused by friction as water flows through pipes
  4. The vertical height of water above the point of measurement Correct answer.

Explanation

Static head is the vertical distance from the free water surface to the point considered, converted to pressure by the height of the water column. It represents the pressure available when there is no flow. Friction loss only arises once water moves, so it is a separate, dynamic effect.

Question 34Water Supply Systems and Pipe Fitting

A stop tap is fitted on the incoming cold water service inside a dwelling. What is its primary function?

  1. To measure the volume of water consumed
  2. To prevent water hammer in the pipework
  3. To allow the householder or plumber to shut off the supply for repairs Correct answer.
  4. To reduce the pressure of the incoming main

Explanation

The internal stop tap (stopcock) is an isolation valve that lets the supply be turned off for maintenance or emergencies without affecting neighbours. It is not a pressure-reducing valve and does not meter flow. Water hammer is controlled by other means such as air chambers or arrestors.

Question 35Water Supply Systems and Pipe Fitting

Why is an air gap considered the most reliable form of backflow protection in a cold water storage arrangement?

  1. It filters suspended solids from the supply
  2. It physically separates the outlet from the flood level of the receiving vessel Correct answer.
  3. It maintains a constant downstream pressure
  4. It closes automatically when the pressure drops

Explanation

An air gap provides a physical, unobstructed space between the discharge outlet and the flood level of the receiving vessel, so backflow cannot occur even under siphonage or back pressure. Because it relies on geometry rather than moving parts, it does not fail in service. Mechanical devices can jam or be wrongly adjusted.

Question 36Water Supply Systems and Pipe Fitting

Which fitting is used to connect two pipes of different diameters in a straight run?

  1. Cap
  2. Reducer Correct answer.
  3. Elbow
  4. Equal tee

Explanation

A reducer is a fitting with different-sized ends that joins a larger pipe to a smaller one in line. An equal tee has all branches the same size, an elbow changes direction, and a cap closes a pipe end. Choosing the correct fitting keeps flow transitions smooth and joints sound.

Question 37Water Supply Systems and Pipe Fitting

What is the recommended minimum depth of cover for a buried cold water service pipe laid under a domestic garden to protect it from frost and damage?

  1. 150 mm
  2. 750 mm Correct answer.
  3. 1500 mm
  4. 300 mm

Explanation

Buried service pipes are normally laid at a depth of around 750 mm to keep them below the frost line and protect them from garden digging. Shallower cover risks freezing and mechanical damage. Much deeper burial is unnecessary and increases excavation cost.

Question 38Water Supply Systems and Pipe Fitting

In a cold water distribution system, what is the purpose of a draw-off tap (bib tap) fitted at the end of a branch?

  1. To control the flow of water delivered to the user Correct answer.
  2. To vent air from the distribution pipe
  3. To prevent contamination entering the branch
  4. To regulate the pressure in the branch pipe

Explanation

A draw-off or bib tap is the terminal outlet that the user opens to obtain water, controlling delivery at the point of use. Pressure regulation and air venting are functions of other components. Contamination prevention is achieved by backflow protection and good design, not by the tap itself.

Question 39Water Supply Systems and Pipe Fitting

A cold water cistern in a roof space supplies a tap 4 m below the water surface. Ignoring friction losses, what approximate pressure is available at the tap (take water density as 1000 kg/m3 and g as 9.81 m/s2)?

  1. 3.9 bar
  2. 0.039 bar
  3. 0.39 bar Correct answer.
  4. 39 bar

Explanation

Static pressure equals density times gravity times height: 1000 x 9.81 x 4 equals about 39 240 Pa, or roughly 0.39 bar. This is the pressure available with no flow. Friction losses in the pipe would reduce the pressure when the tap is opened.

Question 40Water Supply Systems and Pipe Fitting

During flow, a pressure gauge at the base of a riser reads less than the calculated static head. What is the most likely reason?

  1. Friction losses in the pipe reduce the pressure during flow Correct answer.
  2. The gauge is calibrated for a different fluid
  3. Static head increases when water moves
  4. The water density has fallen below 1000 kg/m3

Explanation

When water flows, friction along the pipe wall and fittings causes a pressure drop in the direction of flow, so the pressure at a point is lower than the static value. This is why system design must account for head loss. The other options misstate the physics of the situation.

Question 41Water Supply Systems and Pipe Fitting

A plumber must join a copper cold water pipe to a galvanised steel pipe in a run. What is the key concern that governs the choice of connection method?

  1. The joint must be made with solvent cement
  2. The steel pipe must always be larger than the copper
  3. Copper cannot be joined to steel under any circumstances
  4. Dissimilar metals can cause galvanic corrosion, so a dielectric or isolating fitting is used Correct answer.

Explanation

When copper and galvanised steel are in contact in the presence of water, galvanic corrosion can attack the less noble metal, here the zinc coating and steel. A dielectric union or isolating fitting breaks the electrical path and limits this. The joint is possible but must be made correctly.

Question 42Water Supply Systems and Pipe Fitting

A cistern feeding a cold water tap is fitted with a float valve that will not shut off and water overflows. Which fault is most likely?

  1. The tap has been left open
  2. The float has lost buoyancy or the valve seat is worn Correct answer.
  3. The cistern is too large for the building
  4. The supply pressure is too low

Explanation

Continuous overflow from a cistern fed by a float valve usually means the valve is not closing. A float that has filled with water and lost buoyancy, or a worn seat or washer, prevents shut-off. An open tap would lower the level rather than cause overflow.

Question 43Water Supply Systems and Pipe Fitting

Why are cold water storage cisterns required to have a warning or overflow pipe discharging to a visible external position?

  1. To increase the storage capacity of the cistern
  2. So that a failure of the float valve is noticed before water damage occurs Correct answer.
  3. To allow air to enter the cistern during draw-off
  4. To provide a second supply point for the building

Explanation

A warning pipe discharges overflow water to a conspicuous external point so that a faulty float valve or overfilling is seen early. This limits the risk of water damage inside the building. It does not add capacity or supply, and air entry is handled by the vent.

Question 44Water Supply Systems and Pipe Fitting

A plumber is installing a cold water supply to an outside tap. Which measure best protects the mains supply from contamination?

  1. Fit a pressure-reducing valve on the branch
  2. Fit a double check valve or an air gap at the outlet Correct answer.
  3. Install a stop tap at the tap position
  4. Use a larger diameter pipe to the tap

Explanation

An outside tap is a backflow risk because a hose can be submerged in contaminated water and siphon or back-pressure into the supply. A double check valve or a suitable air gap provides the required protection. Pipe size, pressure reduction and isolation do not prevent backflow.

Question 45Water Supply Systems and Pipe Fitting

In a cold water system, what is the function of an expansion or vent pipe connected from a cistern or cylinder arrangement?

  1. To raise the pressure at the taps
  2. To increase the flow rate at the outlets
  3. To allow for the expansion of water and to release air without allowing contamination in Correct answer.
  4. To filter the water before distribution

Explanation

A vent or expansion pipe provides a path for expanding water and released air, and its open end above the cistern prevents contamination from entering. It does not boost flow or pressure. Filtration is a separate treatment function.

Question 46Water Supply Systems and Pipe Fitting

Which of the following best describes the purpose of a pressure-reducing valve on a cold water supply entering a building from a high-pressure main?

  1. To lower and stabilise the downstream pressure to a safe working level Correct answer.
  2. To increase the pressure at the outlets
  3. To measure the volume of water used
  4. To prevent air from entering the system

Explanation

A pressure-reducing valve throttles the incoming flow to maintain a set lower downstream pressure, protecting fittings and reducing noise and wear. It does not increase pressure or meter consumption. Air exclusion is handled by proper venting and design.

Question 47Water Supply Systems and Pipe Fitting

A plumber needs to connect a branch into an existing cold water main while keeping the run in service. Which fitting arrangement is most appropriate?

  1. An elbow at the branch point
  2. A tee fitted with an isolating valve on the branch Correct answer.
  3. A reducer in the straight run
  4. A cap on the end of the main

Explanation

A tee creates the branch, and an isolating valve on the branch allows the new connection to be worked on without draining the main. A cap, reducer or elbow does not create a controllable branch. This arrangement keeps the main in service during the work.

Question 48Water Supply Systems and Pipe Fitting

What is the main reason for installing a water meter on the incoming cold water service to a dwelling?

  1. To measure and record the volume of water consumed for billing Correct answer.
  2. To reduce the pressure of the supply
  3. To prevent backflow into the mains
  4. To filter debris from the supply

Explanation

A water meter measures the volume passing through it so consumption can be recorded and billed. It does not regulate pressure, prevent backflow or filter debris. Those functions belong to other fittings in the system.

Question 49Water Supply Systems and Pipe Fitting

A cold water cistern is positioned in a loft and supplies a shower on the floor below. The measured static pressure at the shower is low. Which change would most directly increase the available static pressure?

  1. Increase the diameter of the branch pipe to the shower
  2. Fit a larger float valve in the cistern
  3. Raise the cistern to increase the height of water above the shower Correct answer.
  4. Reduce the size of the cistern

Explanation

Static pressure at an outlet is proportional to the vertical height of water above it, so raising the cistern increases the head and therefore the pressure. Larger pipes reduce friction loss during flow but do not raise static pressure. Float valve size and cistern capacity do not change head.

Question 50Water Supply Systems and Pipe Fitting

In cold water pipework, why are bends and elbows kept to a minimum and made with generous radius where possible?

  1. To increase the static head in the system
  2. To make the pipe easier to paint
  3. To allow the pipe to expand more freely
  4. To reduce friction losses and turbulence at changes of direction Correct answer.

Explanation

Sharp changes of direction create turbulence and additional friction loss, lowering pressure at the outlets. Generous-radius bends reduce this loss and quieten flow. Static head is set by height, and expansion and painting are unrelated concerns.