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IESL Part III study materials
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IESL Part III practice questions

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Question 1Agriculture and Plantation Engineering

In a tea factory, the 'withered leaf' moisture content targeted before rolling is most commonly about:

  1. 30–35%
  2. 85–90%
  3. 55–60% Correct answer.
  4. 70–75%

Explanation

Withering removes water so that leaf becomes pliable for rolling. Standard practice brings fresh leaf from roughly 75–80% moisture down to about 55–60%, a loss of about 25% of fresh weight, at which point the leaf is flaccid but not brittle.

Question 2Agriculture and Plantation Engineering

The primary purpose of maintaining a legume cover crop in a rubber plantation interrow is to:

  1. eliminate the need for any fertiliser application
  2. increase latex flow by shading the tapping panel
  3. fix atmospheric nitrogen and suppress weeds Correct answer.
  4. raise the water table for the tap roots

Explanation

Leguminous covers such as Pueraria and Mucuna add nitrogen through symbiosis and form a dense mat that competes with weeds. They also reduce erosion and improve soil organic matter, which is why they are standard in immature rubber clearings.

Question 3Agriculture and Plantation Engineering

A coconut triangle in Sri Lanka refers to the area bounded approximately by which three towns?

  1. Kandy, Nuwara Eliya and Badulla
  2. Jaffna, Mannar and Vavuniya
  3. Galle, Matara and Hambantota
  4. Kurunegala, Puttalam and Chilaw Correct answer.

Explanation

The coconut triangle is the traditional production belt in the north-western and western lowlands, centred on Kurunegala with Puttalam and Chilaw as the coastal vertices. It reflects the concentration of suitable rainfall and sandy soils in that region.

Question 4Agriculture and Plantation Engineering

In paddy cultivation, 'land preparation' with puddling is primarily carried out to:

  1. harden the soil to support machinery
  2. increase soil aeration for root respiration
  3. raise soil pH before basal fertiliser
  4. reduce percolation losses and control weeds Correct answer.

Explanation

Puddling destroys soil structure and creates a low-permeability layer that reduces downward water loss in flooded rice. The standing water layer also suppresses most germinating weeds, giving the crop a competitive advantage.

Question 5Agriculture and Plantation Engineering

The recommended practice for tapping a mature rubber tree is to cut:

  1. horizontally across the panel at any convenient height
  2. deep into the wood to reach the cambium
  3. to a depth just short of the cambium, following the bark spiral Correct answer.
  4. vertically down the trunk from the first branch

Explanation

Latex vessels lie in the bark's inner layers, so the cut should remove a thin shaving ending just before the cambium. Cutting into the cambium or wood damages the tree and yields little latex, while the standard tapping cut follows a descending spiral.

Question 6Agriculture and Plantation Engineering

Which soil moisture condition is most suitable for sowing most tropical field crops by hand?

  1. Permanent wilting point
  2. Field capacity to slightly below it Correct answer.
  3. Saturated, with free water standing on the surface
  4. Air-dry, below hygroscopic coefficient

Explanation

Sowing at or near field capacity gives seed enough moisture for imbibition while leaving air-filled pores for respiration. Saturated soil causes anaerobic rot, and dry soil prevents germination entirely.

Question 7Agriculture and Plantation Engineering

In agricultural engineering, the term 'unit draft' of a tillage implement refers to the draft per unit of:

  1. forward speed
  2. engine power
  3. cross-sectional area of soil disturbed Correct answer.
  4. implement mass

Explanation

Unit draft is the soil resistance per unit of soil cross-section cut, typically expressed in kN per square metre or similar. It allows draft to be estimated for different depths and widths without full-scale field testing.

Question 8Agriculture and Plantation Engineering

Which irrigation method is generally most water-use efficient on a level, closely spaced row crop such as chilli?

  1. Drip irrigation Correct answer.
  2. Wild flooding
  3. Furrow irrigation
  4. Basin flooding

Explanation

Drip delivers water directly to the root zone and minimises evaporation, runoff and deep percolation. On level, closely spaced crops it can achieve much higher application efficiency than surface methods.

Question 9Agriculture and Plantation Engineering

A tea smallholder observes that a block of seedlings has pale yellow leaves with veins remaining green, and the soil pH is 4.2. Which corrective action is most appropriate?

  1. Apply a foliar magnesium spray and address the acidity separately Correct answer.
  2. Flush the bed with saline water
  3. Apply urea to stimulate new growth
  4. Apply agricultural lime to raise pH to about 5.5

Explanation

Interveinal chlorosis with green veins is a classic symptom of magnesium deficiency, which is aggravated by low pH. A foliar magnesium spray gives rapid correction while the underlying acidity is managed with dolomitic lime, which also supplies magnesium.

Question 10Agriculture and Plantation Engineering

In a coconut plantation, the recommended planting density for tall varieties under rainfed conditions is approximately:

  1. 25 palms per hectare
  2. 65 palms per hectare Correct answer.
  3. 400 palms per hectare
  4. 175 palms per hectare

Explanation

Tall coconuts are usually planted at about 7.5 to 8 metres triangular spacing, giving roughly 160 to 180 palms per hectare; however, standard rainfed recommendations often quote about 65 per hectare for wider spacing under dry conditions, and the accepted figure for tall varieties in the triangle is around 175 palms per hectare.

Question 11Agriculture and Plantation Engineering

A rubber smallholder wants to minimise tapping-panel disease. Which combination of practices is most effective?

  1. Tapping on the recommended spiral with rest days and panel hygiene Correct answer.
  2. Tapping at midday when latex flow is highest
  3. Tapping deeper into the cambium and tapping daily
  4. Applying fungicide to the panel only after the panel is exhausted

Explanation

Panel diseases such as mouldy rot and black stripe are favoured by wounding, moisture and repeated tapping. Following the recommended cut, allowing rest days and keeping the panel clean reduces infection pressure and preserves yield.

Question 12Agriculture and Plantation Engineering

In a rice field, a farmer applies 100 kg of urea (46% N) per hectare. How much elemental nitrogen is supplied?

  1. 4.6 kg
  2. 100 kg
  3. 216 kg
  4. 46 kg Correct answer.

Explanation

The nitrogen content is found by multiplying the fertiliser mass by its N percentage: 100 kg × 0.46 = 46 kg N. This is the standard way to compare fertiliser rates across sources such as urea, ammonium sulphate and TSP.

Question 13Agriculture and Plantation Engineering

Which factor most strongly determines the choice of a tractor-implement matching for a two-wheel tractor on a paddy farm?

  1. Colour and brand of the implement
  2. Available drawbar power and soil resistance at working depth Correct answer.
  3. Age of the operator
  4. Number of gears in the gearbox

Explanation

Implement matching balances the power the tractor can deliver at the drawbar against the draft required by the soil at the chosen depth and width. If the implement is too large the engine stalls or wheel slip rises; too small and capacity is wasted.

Question 14Agriculture and Plantation Engineering

A plantation manager wants to reduce soil erosion on a 15% slope planted with tea. Which engineering measure is most directly appropriate?

  1. Increasing the tapping frequency
  2. Applying a higher rate of nitrogen
  3. Constructing contour drains and retaining bunds Correct answer.
  4. Planting in up-and-down rows

Explanation

On sloping land, contour-aligned drains intercept runoff and lead it safely away, while bunds reduce flow velocity and trap sediment. These structures address the erosion process directly, unlike agronomic or harvesting changes.

Question 15Agriculture and Plantation Engineering

In tea manufacture, the purpose of the 'roll' or rotorvane stage is to:

  1. dry the leaf to final moisture
  2. ferment the leaf fully
  3. rupture cell walls so enzymes and substrates mix Correct answer.
  4. separate the leaf from the stalk

Explanation

Rolling or rotorvane action macerates the withered leaf, breaking cell walls so that polyphenol oxidase can contact catechins. This sets up the oxidation (fermentation) stage that develops colour and flavour.

Question 16Agriculture and Plantation Engineering

A field trial compares three fertiliser treatments with four replicates in a randomised complete block design. What is the primary purpose of blocking?

  1. To increase the number of treatments
  2. To remove known field heterogeneity from the error term Correct answer.
  3. To guarantee a significant result
  4. To reduce the number of replicates needed

Explanation

Blocks group plots that are similar, for example along a soil gradient, so that variation between blocks is accounted for separately. The residual error is reduced, giving a more sensitive test of treatment differences.

Question 17Agriculture and Plantation Engineering

Which physiological process explains why rice can survive prolonged soil flooding while most upland crops cannot?

  1. Rice roots contain aerenchyma that transports oxygen internally Correct answer.
  2. Rice stomata remain closed throughout the day
  3. Rice leaves have a waxy cuticle that prevents gas exchange
  4. Rice roots exclude all water uptake

Explanation

Rice forms aerenchyma, a network of gas-filled channels that carries oxygen from the shoot to the roots under anaerobic soil conditions. Upland crops lack this adaptation and suffer root hypoxia in waterlogged soil.

Question 18Agriculture and Plantation Engineering

In a plantation, a pest infestation is found to have developed resistance to a single insecticide after repeated applications. Which management strategy best slows resistance?

  1. Mixing the insecticide with a fertiliser
  2. Rotating among insecticides with different modes of action Correct answer.
  3. Applying the insecticide more frequently
  4. Increasing the dose of the same insecticide

Explanation

Resistance builds when the same mode of action is applied repeatedly, selecting resistant individuals. Rotating modes of action, together with non-chemical controls, reduces selection pressure and delays resistance.

Question 19Agriculture and Plantation Engineering

A coffee grower in the mid-country wet zone notices leaf rust. Which statement about the disease is accurate?

  1. It affects only the roots and never the leaves
  2. It is caused by a virus and spreads only through pruning tools
  3. It is caused by a fungus and is favoured by high humidity and shade Correct answer.
  4. It is eliminated by increasing soil pH above 8

Explanation

Coffee leaf rust is a fungal disease caused by Hemileia vastatrix, which thrives in humid, shaded conditions and produces orange powdery pustules on the underside of leaves. Management combines resistant varieties, canopy management and timely fungicide use.

Question 20Agriculture and Plantation Engineering

A tea estate wants to estimate the yield of a block from a sample. Which sampling approach gives the most representative estimate?

  1. Harvesting only the edge rows near the road
  2. Selecting the tallest bushes in the block
  3. Sampling only after heavy rain
  4. Taking a random sample of plucking points across the block Correct answer.

Explanation

Representativeness requires that every part of the block has an equal chance of being sampled. A random sample across the block avoids the bias introduced by edges, tall bushes or weather events.

Question 21Agriculture and Plantation Engineering

A farmer applies 200 kg of a 12-24-12 compound fertiliser per hectare. How much P2O5 is applied?

  1. 24 kg
  2. 48 kg Correct answer.
  3. 72 kg
  4. 12 kg

Explanation

The middle figure of the N-P-K analysis is the percentage of P2O5. Multiplying 200 kg by 0.24 gives 48 kg of P2O5 per hectare.

Question 22Agriculture and Plantation Engineering

In a sprinkler irrigation system, the uniformity of water application is best improved by:

  1. Reducing the pipe diameter
  2. Selecting nozzle spacing matched to the wetted diameter and pressure Correct answer.
  3. Removing the pressure regulator
  4. Increasing the operating pressure indefinitely

Explanation

Sprinkler uniformity depends on overlapping the wetted patterns correctly. Spacing nozzles at the recommended fraction of wetted diameter, at the design pressure, gives an even distribution; excessive pressure causes misting and poor overlap.

Question 23Agriculture and Plantation Engineering

A plantation soil has a bulk density of 1.4 g/cm3 and a particle density of 2.6 g/cm3. What is the approximate porosity?

  1. 26%
  2. 54%
  3. 36%
  4. 46% Correct answer.

Explanation

Porosity = 1 − (bulk density / particle density) = 1 − (1.4 / 2.6) = 1 − 0.538 = 0.462, or about 46%. This is typical for a medium-textured agricultural soil.

Question 24Agriculture and Plantation Engineering

A tractor develops a drawbar pull of 8 kN while moving at 6 km/h. What is the approximate drawbar power?

  1. 26.7 kW
  2. 13.3 kW Correct answer.
  3. 4.8 kW
  4. 48 kW

Explanation

Drawbar power = force × speed. Converting 6 km/h to 1.667 m/s and multiplying by 8 kN gives about 13.3 kW. Consistent SI units are essential in this calculation.

Question 25Agriculture and Plantation Engineering

A tea factory processes 10,000 kg of fresh leaf at 78% moisture and withers it to 60% moisture. What is the approximate withered leaf mass?

  1. 8,200 kg
  2. 6,000 kg
  3. 5,500 kg Correct answer.
  4. 7,800 kg

Explanation

Dry matter is conserved: 10,000 × 0.22 = 2,200 kg. At 60% moisture the dry matter is 40% of the withered mass, so mass = 2,200 / 0.40 = 5,500 kg.

Question 26Agriculture and Plantation Engineering

A young rubber plantation is to be established on a slope where surface runoff is expected during the monsoon. Which land-preparation practice best reduces soil loss before the canopy closes?

  1. Deep ploughing up and down the slope to encourage rapid infiltration
  2. Constructing a single large drainage channel at the bottom of the block
  3. Establishing cover crops in the inter-row spaces and along the contour Correct answer.
  4. Burning the existing vegetation and leaving the soil bare until planting

Explanation

Ground cover intercepts raindrop energy and slows surface flow, and contour-aligned strips trap sediment moving downslope, so cover cropping is the standard protective measure during the immature phase. Bare soil after burning is highly erodible, and a single downslope channel removes water without reducing detachment on the slope itself.

Question 27Agriculture and Plantation Engineering

A coconut estate plans supplementary irrigation for a mature palms block. The available water supply is limited and the soil is a deep sandy loam. Which combination of scheduling approach and application method is most appropriate?

  1. Irrigate only when palms show visible wilting, using overhead sprinklers in the heat of the day
  2. Irrigate at fixed calendar intervals using flood basins around each palm
  3. Schedule from pan evaporation and tensiometer readings, applying water through drip or micro-sprinklers Correct answer.
  4. Apply a single heavy irrigation at the start of the dry season by furrow along the palm rows

Explanation

Scheduling from evaporation and soil-moisture readings replaces guesswork with measured crop demand, and localized drip or micro-sprinkler delivery limits losses from evaporation, deep percolation and wetting of unproductive ground. Sandy loam holds limited plant-available water, so frequent, measured, localized applications suit it better than large intermittent flooding.

Question 28Agriculture and Plantation Engineering

A tea factory receives 5,000 kg of fresh leaf at 76% moisture and withers it to 68% moisture (both on a wet basis). Assuming no dry-matter loss, what is the approximate mass of withered leaf?

  1. 4,600 kg
  2. 3,400 kg
  3. 3,750 kg Correct answer.
  4. 4,250 kg

Explanation

Dry matter in the fresh leaf is 5,000 x 0.24 = 1,200 kg, and this is unchanged by withering. At 68% moisture the dry matter is 32% of the final mass, so the withered mass is 1,200 / 0.32 = 3,750 kg.

Question 29Building Services Engineering

In a low-rise building drainage system, what is the primary function of the vent pipe connected to a soil stack?

  1. To provide a secondary path for stormwater drainage
  2. To increase the discharge velocity inside the stack
  3. To carry away condensate forming on the outside of the stack
  4. To equalise air pressure in the system and protect trap seals from siphonage Correct answer.

Explanation

A vent pipe admits air to the drainage system so that pressure fluctuations caused by falling water are equalised. Without adequate venting, partial vacuum in the stack can siphon the water seal from traps, allowing foul air into the building. Venting therefore protects trap seals rather than carrying water or improving flow velocity.

Question 30Building Services Engineering

Which statutory document in Hong Kong sets out the minimum requirements for the design and installation of fire service installations in buildings?

  1. The Buildings Ordinance and its associated regulations Correct answer.
  2. The Waterworks Ordinance
  3. The Electricity Ordinance
  4. The Factories and Industrial Undertakings Ordinance

Explanation

Fire service installations in buildings fall under the Buildings Ordinance and the regulations made under it, together with codes of practice issued by the Buildings Department. The other ordinances govern electricity supply, water supply, and occupational safety respectively, and do not set building fire service standards.

Question 31Building Services Engineering

A room has a sensible heat gain of 12 kW and a latent heat gain of 3 kW. What is the sensible heat ratio (SHR) of the room load?

  1. 0.75
  2. 0.25
  3. 1.25
  4. 0.80 Correct answer.

Explanation

The sensible heat ratio is the sensible load divided by the total load, so SHR = 12 / (12 + 3) = 0.80. The value indicates the proportion of the cooling load that changes dry-bulb temperature, with the remainder being latent. It is used to select and check the apparatus dew point of the cooling coil.

Question 32Building Services Engineering

In a chilled water system, what is the main purpose of a differential pressure bypass valve across the supply and return headers?

  1. To regulate the chilled water temperature leaving the chiller
  2. To prevent reverse flow through the cooling tower
  3. To drain the system during maintenance
  4. To maintain minimum chiller evaporator flow as terminal units close Correct answer.

Explanation

As two-way terminal valves close, system flow falls and evaporator flow can drop below the chiller manufacturer's minimum. A differential pressure bypass valve opens at a set pressure difference to recirculate water and keep evaporator flow above that minimum. It does not control chilled water temperature or drain the circuit.

Question 33Building Services Engineering

Which type of fire sprinkler system has pipes normally filled with air under pressure, with water admitted only after a sprinkler operates?

  1. Deluge system
  2. Pre-action system
  3. Wet pipe system
  4. Dry pipe system Correct answer.

Explanation

In a dry pipe system the piping upstream of the control valve holds compressed air, and the drop in pressure when a sprinkler fuses opens the dry pipe valve to admit water. This arrangement suits spaces where water in the pipes could freeze. Wet pipe systems are permanently water-filled and deluge systems open all heads simultaneously.

Question 34Building Services Engineering

What is the principal reason a fire lift lobby is provided with a fire-rated enclosure and positive pressurisation?

  1. To keep the lift car interior at a comfortable temperature
  2. To increase the rated speed of the lift
  3. To reduce the electrical load of the lift motor
  4. To prevent smoke from entering the escape route and lift lobby Correct answer.

Explanation

A protected fire lift lobby with pressurisation maintains a positive pressure relative to adjacent areas so that smoke cannot migrate into the lobby. This preserves a tenable environment for occupants and firefighters using the lift during an emergency. Thermal comfort, motor load, and lift speed are unrelated to this design measure.

Question 35Building Services Engineering

The maximum demand of an installation is 120 kVA at a power factor of 0.8. What is the active power demand?

  1. 96 kW Correct answer.
  2. 150 kW
  3. 120 kW
  4. 60 kW

Explanation

Active power equals apparent power multiplied by power factor, so 120 kVA × 0.8 = 96 kW. The remaining 72 kvar is reactive power. Confusing kVA with kW would give the incorrect answer of 120 kW.

Question 36Building Services Engineering

Which earthing arrangement is described by a system in which the neutral of the supply is earthed and the exposed conductive parts of the installation are connected to separate earth electrodes?

  1. IT
  2. TT Correct answer.
  3. TN-C-S
  4. TN-S

Explanation

In a TT system the supply neutral is earthed at the source, but the installation's exposed conductive parts are connected to a local earth electrode that is independent of the supply earth. This differs from TN systems, where protective conductors are connected back to the earthed neutral. In an IT system the supply is either unearthed or earthed through a high impedance.

Question 37Building Services Engineering

In a domestic hot water system, what is the function of a thermostatic mixing valve at the outlet of a calorifier?

  1. To limit the delivered water temperature to a safe level Correct answer.
  2. To measure the volume of hot water drawn
  3. To prevent backflow into the cold water supply
  4. To increase the storage temperature of the cylinder

Explanation

A thermostatic mixing valve blends hot and cold water to deliver a controlled, safe outlet temperature, reducing the risk of scalding. It does not raise storage temperature or meter consumption. Backflow prevention is the role of a separate check or non-return valve.

Question 38Building Services Engineering

A pump delivers 10 L/s against a total head of 20 m. Taking water density as 1000 kg/m³ and gravitational acceleration as 9.81 m/s², what is the hydraulic power output?

  1. 19.6 kW
  2. 1.96 kW Correct answer.
  3. 196 kW
  4. 0.196 kW

Explanation

Hydraulic power equals density × gravitational acceleration × flow rate × head, so 1000 × 9.81 × 0.010 × 20 = 1962 W, about 1.96 kW. The flow must be converted from litres per second to cubic metres per second. Shaft power would be higher because of pump efficiency.

Question 39Building Services Engineering

Which luminaire characteristic best describes the ratio of luminous flux leaving the luminaire to the luminous flux of the lamps it contains?

  1. Utilisation factor
  2. Light output ratio Correct answer.
  3. Luminous efficacy
  4. Glare index

Explanation

The light output ratio expresses how much of the lamp flux escapes the luminaire, accounting for absorption and reflection losses within the fitting. Luminous efficacy measures lumens per watt, and the utilisation factor relates flux reaching the working plane to that emitted. Glare index describes visual discomfort rather than efficiency.

Question 40Building Services Engineering

Which of the following is the most appropriate method for controlling the speed of a standard squirrel-cage induction motor driving a variable-flow pump?

  1. A star-delta starter
  2. A variable frequency drive Correct answer.
  3. A soft starter
  4. A direct-on-line starter

Explanation

A variable frequency drive changes the supply frequency to the motor, allowing continuous speed control and reducing power consumption at part load. Star-delta, direct-on-line, and soft starters only affect starting current and cannot vary running speed. For a variable-flow pump, speed control is the efficient means of matching output to demand.

Question 41Building Services Engineering

What is the primary purpose of a building management system in a commercial building?

  1. To provide emergency lighting during a power failure
  2. To supply standby power to fire service installations
  3. To monitor and control building services plant for efficient operation Correct answer.
  4. To treat domestic water for potable use

Explanation

A building management system supervises and controls mechanical and electrical plant, gathering data and adjusting operation to maintain conditions efficiently. It does not itself generate emergency lighting or standby power, nor does it treat water. Those functions belong to dedicated systems that the building management system may only monitor.

Question 42Building Services Engineering

A natural ventilation strategy relies on the stack effect. Which combination of conditions produces the greatest buoyancy-driven airflow through a vertical shaft?

  1. A short shaft with equal inside and outside temperatures
  2. A tall shaft with a large temperature difference between inside and outside Correct answer.
  3. A tall shaft with equal inside and outside temperatures
  4. A short shaft with a small temperature difference

Explanation

Buoyancy pressure in a shaft increases with shaft height and with the density difference between the internal and external air, which is driven by temperature difference. A taller shaft and a larger temperature difference therefore both increase the driving pressure and the resulting airflow. Equal temperatures remove the driving force entirely.

Question 43Building Services Engineering

In a plumbing system, what is the purpose of an air gap at a cold water storage tank inlet?

  1. To allow the tank to overflow safely
  2. To reduce the noise of water entering the tank
  3. To measure the inflow rate
  4. To prevent contamination of the supply by backflow or backsiphonage Correct answer.

Explanation

An air gap provides a physical separation between the inlet and the maximum water level, so that no backflow or backsiphonage can draw contaminated water into the supply. It is a fundamental backflow prevention measure. Overflow is handled separately by a warning or overflow pipe.

Question 44Building Services Engineering

Which gas is commonly used as a clean extinguishing agent for total flooding of occupied spaces containing sensitive electronic equipment?

  1. Carbon dioxide
  2. Dry nitrogen
  3. Halon 1301
  4. HFC-227ea Correct answer.

Explanation

HFC-227ea is a clean agent that extinguishes fire without leaving residue and is designed for use in occupied spaces at concentrations that remain safe. Carbon dioxide is hazardous to occupants at extinguishing concentrations, and halon production is phased out under environmental controls. Nitrogen reduces oxygen and is not suitable for occupied spaces.

Question 45Building Services Engineering

A room requires a sound pressure level reduction of 20 dB at a boundary. Which measure is most effective at reducing airborne noise transmission between two rooms?

  1. Increasing the mass of the separating wall Correct answer.
  2. Opening a small transfer grille in the wall
  3. Increasing the reverberation time in the source room
  4. Adding a porous acoustic foam layer to the wall surface

Explanation

Airborne sound transmission through a separating element is governed mainly by its mass per unit area, following the mass law, so increasing wall mass raises transmission loss. Porous foam absorbs sound within a room but adds little to the separating element's transmission loss. A transfer grille would create a flanking path and reduce performance.

Question 46Building Services Engineering

Which of the following describes the function of a pressure reducing valve on a high-rise building's water supply?

  1. To prevent water hammer in the riser
  2. To measure the flow through the riser
  3. To maintain a lower, controlled downstream pressure despite high supply pressure Correct answer.
  4. To boost pressure to upper floors

Explanation

A pressure reducing valve throttles the flow to maintain a set lower downstream pressure, protecting fittings and outlets from excessive pressure in tall buildings. Boosting pressure requires a pump, and water hammer protection is provided by accumulators or surge vessels. Flow measurement is done by a meter.

Question 47Building Services Engineering

In a cooling tower, what is the primary purpose of the drift eliminator?

  1. To prevent biological growth in the basin
  2. To reduce the loss of water droplets entrained in the exhaust air Correct answer.
  3. To increase the cooling range of the tower
  4. To reduce the fan noise level

Explanation

Drift eliminators are baffles that capture water droplets carried in the air stream, reducing water loss and preventing Legionella-bearing aerosol from being released. They do not themselves increase cooling range or control biological growth. Noise reduction is achieved by fan and casing design.

Question 48Building Services Engineering

Which condition must be satisfied for a fire service installation to be accepted as an alternative solution under a performance-based fire engineering approach?

  1. It must demonstrate equivalent or better safety than the prescribed standard Correct answer.
  2. It must use the same materials as the prescribed standard
  3. It must be approved by the building owner alone
  4. It must be cheaper than the prescribed standard

Explanation

Performance-based design allows alternative solutions where engineering analysis shows that the fire safety objectives are met to a level equivalent to or better than the deemed-to-satisfy provisions. Cost and material identity are not acceptance criteria. Approval requires submission to and acceptance by the building authority.

Question 49Building Services Engineering

A lift installation serves a 30-storey office building. Which quantity is normally used to express the handling capacity of the lift system?

  1. The maximum travel speed of the lift car
  2. The number of stops per floor
  3. The percentage of building population transported in five minutes Correct answer.
  4. The rated load of the lift car in kilograms

Explanation

Handling capacity is expressed as the percentage of the building population that the lift system can transport during the peak five-minute period. It depends on car capacity, speed, number of stops, and round trip time. Car speed and rated load are input parameters rather than the capacity measure itself.

Question 50Building Services Engineering

In a drainage system, what is the purpose of a rodding eye or access chamber?

  1. To allow air to enter the drain for ventilation
  2. To measure the flow rate in the drain
  3. To provide access for clearing blockages in the drain Correct answer.
  4. To prevent the entry of stormwater into the foul drain

Explanation

Rodding eyes and access chambers provide points at which maintenance staff can insert rods or cleaning equipment to clear blockages and inspect the drain. Ventilation is provided by the vent pipe system, and flow measurement uses a separate device. Preventing stormwater entry is achieved by the drainage layout and traps.