WorksheetsRevision
Total questions: 54
Worksheet time: 27mins
What is the estimated percentage of electricity used by air-conditioning system in Singapore building sector?
10%
30%
50%
70%
Duct systems are classified with respect to velocity and
Density.
humidity.
pressure.
temperature.
4 factors affecting thermal comfort are air temperature, air movement and air cleanliness
odour
humidity
air change
air volume
Which type of duct has the advantage of cheaper material cost?
Oval ducts
Round ducts
Square ducts
Rectangular ducts
Air-conditioning system of the building shall be sustainable, efficient and effective to
reduce operating cost.
shorten system lifespan.
minimise occupants’ comfort.
increase energy consumption.
In compliance with Singapore Standard for indoor air quality (IAQ), measurement of IAQ parameters should be made on
2 hours basis.
4 hours basis.
6 hours basis.
8 hours basis.
Before servicing of any refrigerant system/electrical system, it is advisable to
switch off all power.
stop all production works.
look for a qualified engineer.
seek the help of the operator.
The primary purpose of a duct system is to
filter re-circulated room air.
increase room temperature.
reduce moisture content in the space.
deliver and remove air within conditioned space.
The respective condenser water entering and leaving temperature is
8°C and 12°C.
16°C and 20°C.
21°C and 26°C.
29.5°C and 35°C.
An office building is fully air-conditioned during the operation hours. What is the temperature range of the office in compliance with Singapore Standard Code of Practice SS553:2016?
11°C – 18°C.
17°C – 20°C.
23°C – 25°C.
25°C – 28°C.
The method that can be adopted to increase air quantity of an air-conditioned space is to
introduce more outdoor air.
lower the speed of fan motor.
increase the numbers of supply air diffusers.
reduce unnecessary fitting to decrease the system resistance.
Water-cooled packaged air-conditioners can be divided into 2 main categories namely
air and water sections
discharge and suction sections.
high and low pressure sections.
air handling and refrigeration sections.
If chilled water temperature of an air-conditioning system is increased by 1°C, the energy consumption of that system can be reduced by
2%
3%
4%
5%
Calculate the chiller efficiency if its cooling capacity is 1000RT and the electrical ...
The chiller efficiency is 0.7 kW/RT.
The chiller efficiency is 1.2 kW/RT.
The chiller efficiency is 2.5 kW/RT.
The chiller efficiency is 3.0 kW/RT.
If the chiller efficiency is 0.5 and the cooling power is 500kW.
0.2.
0.5.
2.0.
7.0.
Air handling unit typically contains mixing box, air filter, dehumidifier, fan, motor and
condenser.
cooling coil.
compressor.
condensing unit.
AHU air filter shall be cleaned and washed every
day.
month.
quarter.
year.
Poor maintenance of air-conditioning system shall
reduce system efficiency.
improve system efficiency.
increase equipment life span.
maintain occupants thermal comfort.
Condenser water quality is to be tested quarterly to
eliminate flooding.
maintain water flowrate.
ensure temperature is within range.
prevent scale and corrosion build up.
The component that is able to minimise heat flow into the cooled interior of the air handling unit is a/an
accumulator.
vibration isolator.
thermal insulation.
flexible connection.
If the supply air in their office is not cold enough. What is the likely reason for this problem?
Fan bearing is worn out.
Chilled water flowrate is insufficient.
Air velocity in the AHU is more that 2.5m/s.
The height of AHU condensate pipe is insufficient.
One of the effects of air pollutants and poor indoor air quality in the office building is:
Increased risk of respiratory problems
Improved concentration
Enhanced air freshness
Boosted immune system
21. is
lost of productivity.
positive pressurised room.
increase room temperature.
Improved occupants thermal comfort.
In VRF air-conditioning system, compressor speed can vary by changing the frequency of the power supply to the compressor because of the
inverter.
VAV box.
volume control damper.
differential pressure gauge.
The method to prevent any liquid refrigerant from flowing back into the compressor suction in VRV air-conditioning system is
oil receiver is installed.
control valve is fully open.
increase size of oil separator.
ensure the accumulator has sufficient capacity.
How often is the AHU condensate drain pan cleaned?
Daily.
Monthly.
Quarterly.
Yearly.
How often is condenser water quality tested?
Daily.
Monthly.
Quarterly.
Yearly.
Maintenance carried out periodically to ensure equipment is in good operating condition is known as
routine maintenance.
planned maintenance.
corrective maintenance.
breakdown maintenance
What type of testing tool can be used to check for electrical component degradation?
Acoustic.
Pressure.
Thermographic.
Vibration.
What type of testing analysis to be used in order to detect the likely of AHU fan belt slippage?
Acoustic.
Pressure.
Thermografic.
Vibration.
Discuss the function of BMS central station.
Receive signals from field devices.
Send or receive data directly to controllers.
Able to print either reports or online alarms.
Provide user interface with the control system.
The function of a motor is to convert
power into kinetic energy.
power into mechanical energy.
electrical energy into fluid dynamic.
electrical energy into mechanical energy.
One of the advantages of using building management system is because it
improves security.
reduces material wastage.
eliminates carbon emission.
increases occupants comfort level.
Cavitation in pumps may cause
higher fluid flowrate.
reduction in capacity.
increase in suction pressure.
decrease in fluid temperature.
Recently many occupants of building XYZ complain that they suffer from sore throat, headache and running nose. What can be the likely cause of this sickness?
Humidity level of the occupied space is 65%.
The temperature of occupied spaces is reduced.
The fresh air supplied in the conditioned space increases.
Improper maintenance of the building air-conditioning system.
One of the controlled variable used in air-conditioning system application is
Temperature
Voltage
Current
Speed
What is another function of BAS besides controlling?
Locating.
Playing.
Reporting.
Running.
If an air-conditioning system fails, it can have significant financial consequences due to
reduce manpower cost.
extended equipment life span.
extended downtime for repairs.
lower temperature in air-con spaces.
What will occur when a fan coil unit cools air?
Compression.
Condensation.
Evaporation.
Leakage.
In order to prevent any liquid refrigerant from flowing back into the compressor suction, accumulator shall have
efficient sensor.
pressure gauge.
metering device.
sufficient capacity.
The voltage rating for a three-phase motor is
115V.
230V.
415V.
500V.
If a pump fails to deliver the liquid, it may be due to
dirt in bearing.
foundation not rigid.
mechanical seal defect.
wrong rotating direction.
To avoid energy waste and overworking of an air-conditioning system, maintenance plan should be based on
humidity.
energy bill.
system cost.
system down time.
One of the advantages of using VRV/VRF air-conditioning system is
accessible.
shorter lifespan.
energy efficiency.
high operation cost.
When an equipment is isolated for repairs, it is important to ________
covered it.
removed it.
tag and lock it.
inform supervisor.
When performing maintenance work, it is important that all metal parts of air-conditioning mechanisms should be ________
cleaned.
covered.
grounded.
protected.
Which type of gloves is used, when handling system components after a compressor motor-burnt out?
Cotton.
Leather.
Plastic.
Rubber.
The three analysis tools use for predictive maintenance are vibration, acoustic and
humidity.
pressure.
thermographic.
carbon detection.
Analysing vibration in rotating components of any machine can provide a remarkably detailed picture of many different
heat problems.
thermal problems.
acoustic problems.
mechanical problems.
49. Scale formation in water piping of an air-conditioning system will
reduce heat transfer efficiency
increase water flow rate
prevent corrosion completely
improve cooling performance
Which of the following actions will reduce the water flow rate?
reduce the water flow rate.
increase the water flow rate.
increase the system efficiency.
reduce the power consumption.
The effectiveness of a cooling tower can be improved by
lowering wet bulb temperature of the leaving air.
lowering wet bulb temperature of the entering air.
Increasing dry bulb temperature of the leaving air.
increasing dry bulb temperature of the entering air.
The advantage of the constant air volume system is
initial cost is high.
complex in design.
operating cost is low.
maintenance is easier.
The VAV terminal box of a VAV system should be set to a minimum opening of
10%
20%
30%
40%
