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HVAC CDC's > Volume 4 > Flashcards

Volume 4 Flashcards

1
Q

(601) How is static electricity best controlled?
a. 100% cotton clothing.
b. Avoiding flammable leaks.
c. Visually inspect static electricity.
d. Grounding, bonding, humidifying.

A

d. Grounding, bonding, humidifying.

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2
Q

(601) Grounded wires carrying off static charges
a. bonds with static charges.
b. creates an electrical hazard.
c. increases the difference in electrical potential.
d. neutralizes the difference in electrical potential.

A

d. neutralizes the difference in electrical potential.

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3
Q

(601) A fuel spill should be reported when how many gallons or more is leaked or spilled?
a. 5.
b. 10.
c. 25.
d. 35.

A

c. 25.

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4
Q

(601) A leak of 35 gallons should be reported to the state regulator within
a. 24 hours.
b. 48 hours.
c. 72 hours.
d. 1 week.

A

a. 24 hours.

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5
Q

(602) When the viscosity of an oil is decreased, how does it affect the oil?
a. Worse for atomization.
b. More difficult to flow.
c. Harder to pump.
d. Easier to pump.

A

d. Easier to pump.

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6
Q

(602) Which type of condition could cause a blocked burner?
a. Clean oil.
b. Sludge in oil.
c. Low viscosity.
d. Very low viscosity.

A

b. Sludge in oil.

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7
Q

(603) Which procedure is best to use for efficiency if the tank is below the level of the burner?
a. A two-stage pump with a three-pipe system.
b. A single-stage pump with a two-pipe system.
c. A two-stage pump with a single-pipe system.
d. A two-stage pump with a two-pipe system.

A

d. A two-stage pump with a two-pipe system.

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8
Q

(603) Why is a galvanized pipe not used with fuel lines?
a. It can cause corrosion problems.
b. Because it will begin to conduct electricity.
c. Galvanized pipe is too restrictive to oil flow.
d. The galvanized steel explodes on contact with fuel oil.

A

a. It can cause corrosion problems.

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9
Q

(603) Why is a gate valve located on the tank side of the strainer?
a. To protect the tank during cleaning.
b. To permit greater flow to the strainer.
c. To collect sludge before it hits the strainer.
d. So that the suction line is isolated when cleaning the strainer.

A

d. So that the suction line is isolated when cleaning the strainer.

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10
Q

(604) Liquefied petroleum gas (LPG) is stored and transported in
a. its liquid state.
b. its solid state.
c. its gaseous state.
d. a mixture of natural gas.

A

a. its liquid state.

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11
Q

(604) Ten percent of a liquefied petroleum gas (LPG) tank is not filled to
a. save gas for another tank.
b. accommodate for expansion.
c. accommodate for contraction.
d. accommodate for freezing temperatures.

A

b. accommodate for expansion.

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12
Q

(605) The action that happens to the safety shutoff valve in the main burner line once a pilot flame is detected is it
a. remains closed until a technician opens it.
b. locks out for safety.
c. is opened.
d. is closed.

A

c. is opened.

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13
Q

(605) Which device removes any accumulated gas in the combustion chamber burner?
a. Blower.
b. Dampers.
c. Reset switch.
d. Venturi effect.

A

a. Blower.

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14
Q

(606) What are the three categories of gas supply systems?
a. Low, high, and superheated.
b. Ultralow, low, and medium.
c. Low, mid-level, and high.
d. Low, medium, and high.

A

d. Low, medium, and high.

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15
Q

(607) Identify what you would use to determine if water is in the oil.
a. Vent caps.
b. Oil level gauge.
c. Five cups of water dye.
d. Tank stick with water finding paste.

A

d. Tank stick with water finding paste.

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16
Q

(608) Identify all the necessary elements that must be present for combustion?
a. Heat and air.
b. Air and fuel.
c. Heat and a spark.
d. Heat, air, and fuel.

A

d. Heat, air, and fuel.

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17
Q

(608) How much of the flue gases are made up of nitrogen?
a. 59%.
b. 66%.
c. 79%.
d. 88%.

A

c. 79%.

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18
Q

(608) Why is carbon monoxide undesirable in flue gases, besides the fact that it is dangerous?
a. Its presence in flue gases represents a waste of fuel.
b. When it is present there is less than 20% efficiency.
c. When it is present there is less than 30% efficiency.
d. Its presence in flue gases means that combustion is not taking place.

A

a. Its presence in flue gases represents a waste of fuel.

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19
Q

(608) The turndown of a burner is the ratio of the
a. maximum firing rate to carbon dioxide.
b. minimum firing rate to the average firing rate.
c. carbon monoxide to excess air and pure oxygen.
d. maximum firing rate to the minimum firing rate.

A

d. maximum firing rate to the minimum firing rate.

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20
Q

(609) Identify the relationship between excess air and complete combustion.
a. Excess air will blow the flame out and stop combustion.
b. It is less than what is needed for theoretical combustion.
c. Excess air is needed for complete combustion.
d. Excess air saves heat from leaving the stack.

A

c. Excess air is needed for complete combustion.

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21
Q

(609) The condition that affects infiltration losses is the volume of
a. make up air.
b. inside air that stays indoors.
c. outside air that escapes outside.
d. outside air that leaks through cracks and crevices.

A

d. outside air that leaks through cracks and crevices.

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22
Q

(610) A pressure-gun burner achieve flame turbulence by
a. modulating the gas control valve.
b. fully closing and then opening the fuel valve.
c. causing straight air flow as it leaves the gun tube.
d. causing the air to whirl as it leaves the gun tube.

A

d. causing the air to whirl as it leaves the gun tube.

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23
Q

(611) The effect too much air has on a flame is that it makes it
a. short, noisy, and keeps it near the burner.
b. short, noisy, and tends to pull away from the burner.
c. short, quiet, and tends to pull away from the burner.
d. long, noisy, and tends to pull away from the burner.

A

b. short, noisy, and tends to pull away from the burner.

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24
Q

(611) Identify the cause of a high CO2 reading during combustion.
a. Zero air supplied for combustion.
b. Insufficient draft and over firing.
c. Sufficient draft and over firing.
d. No fuel or gas in the supply line.

A

b. Insufficient draft and over firing.

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25
Q

(612) Where does the signal to open and close a gas valve come from on modern equipment?
a. Manually operated switches.
b. Manually operated valves.
c. Pneumatic devices.
d. Control board.

A

d. Control board.

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26
Q

(613) How does an inspirating burner bring in primary air?
a. Large fans.
b. Venturi action.
c. Forced draft action.
d. Pulse burner principles.

A

b. Venturi action.

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27
Q

(613) The pulse burner introduce gas and air
a. in operating phases.
b. every 30 seconds.
c. in one single phase.
d. every 45 seconds.

A

a. in operating phases.

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28
Q

(613) Where does gas and primary air mix in a premixing burner?
a. Before they reach the burner port.
b. After they reach the burner port.
c. In the combustion chamber.
d. Inside the burner port.

A

a. Before they reach the burner port.

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29
Q

(613) How long will an intermittent pilot stay lit?
a. During the entire run period.
b. During ignition sequences.
c. For 2 to 5 seconds.
d. Never.

A

a. During the entire run period.

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30
Q

(614) The mixture of air is affected by a reduced gas velocity because it allows for
a. incomplete mixing before it exits the burner ports.
b. complete mixing before it exits the burner ports.
c. complete mixing after it exits the burner ports.
d. partial mixing after it exits the burner ports.

A

b. complete mixing before it exits the burner ports.

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31
Q

(615) What affects the voltage generated by a thermocouple?
a. Ignition detection.
b. Temperature sensed by fan controls.
c. Temperature sensed at the limit control switch.
d. Temperature difference between hot and cold junctions.

A

d. Temperature difference between hot and cold junctions.

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32
Q

(615) The relationship between a sensing thermocouple and a standing pilot is the
a. pilot ignites the thermocouple.
b. thermocouple lights the pilot.
c. thermocouple senses the standing pilot and determines if it is lit correctly.
d. standing pilot senses the thermocouple and determines if it is lit correctly.

A

c. thermocouple senses the standing pilot and determines if it is lit correctly.

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33
Q

(615) Hot-surface ignitors are located in relation to gas flow by a location in which
a. air will pass over it when the gas valve closes.
b. gas will pass over it when the gas valve opens.
c. gas will pass over it when the gas valve closes.
d. gas will avoid it when the gas valve opens.

A

b. gas will pass over it when the gas valve opens.

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34
Q

(615) The way the control module can determine if the glow coil is hot enough to ignite the fuel is due to the resistance of
a. fan pressure.
b. limit control.
c. glow coil or a time delay.
d. solenoid coil or a time delay.

A

c. glow coil or a time delay.

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35
Q

(615) A solid-state device can detect the presence of a flame because the pilot flame conducts the
a. current to the grounded pilot.
b. voltage to the grounded pilot.
c. current to the grounded motor.
d. current to the grounded bearings.

A

a. current to the grounded pilot.

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36
Q

(616) Which type of work is checked for completion during the pre-operational inspection of a gas burner?
a. Troubleshooting.
b. Operations Management work.
c. Operation of the motor and burner.
d. Installation, repair and cleanup work.

A

d. Installation, repair and cleanup work.

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37
Q

(616) Identify what the thermocouple is inspected for during a pre-operational inspection?
a. Carbon deposits, corrosion or heat damage.
b. Proper insulation of hot junction.
c. Ensure flame will not be near it.
d. Proper output voltage.

A

a. Carbon deposits, corrosion or heat damage.

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38
Q

(616) How long should you wait for gas to clear from the combustion chamber?
a. 5 minutes.
b. 15 minutes.
c. 35 minutes.
d. 24 hours to be safe.

A

a. 5 minutes.

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39
Q

(617) How often should you remove, dismantle, and clean a main burner?
a. Never.
b. Every 10 years.
c. Every 2 months.
d. At least once a year.

A

d. At least once a year.

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40
Q

(618) A forced draft affect oil burners because it
a. decreases oil flow.
b. increases their oil burning capacity.
c. decreases their oil burning capacity.
d. forces them to be converted to gas burners.

A

b. increases their oil burning capacity.

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41
Q

(618) The effect a nozzle has on high pressure oil passing through it is it
a. will not affect the oil due to high pressures.
b. creates a star shaped flow.
c. produces a fine mist.
d. blocks flow.

A

c. produces a fine mist.

42
Q

(618) A gun type burner get its 10,000 volt electric spark from the
a. fan limit switch once it closes.
b. step-down transformer.
c. step-up transformer.
d. solenoid valve.

A

c. step-up transformer.

43
Q

(618) Where is the high pressure gun type nozzle’s angle of spray located?
a. On the nozzle’s filter.
b. Inside the nozzle filter.
c. On the side of the nozzle.
d. Near the outlet of the nozzle.

A

c. On the side of the nozzle.

44
Q

(619) What is the combustion chamber inspected for during an oil burner pre-operational inspection?
a. Cabinet insulation.
b. Pools of unburned oil.
c. Proper asbestos insulation.
d. Proper opening and closing.

A

b. Pools of unburned oil.

45
Q

(619) Which action should be taken if pools of unburned oil have flooded the combustion chamber?
a. Remove the burn and light the pool of oil.
b. Light the burner to burn off the flooded oil.
c. Light the burner and run out of the boiler room.
d. Soak it up with rags and purge the combustion chamber.

A

d. Soak it up with rags and purge the combustion chamber.

46
Q

(620) How is the spark moved into the path of the oil spray?
a. Through gas pressure.
b. Air from the fan will blow the spark into the path.
c. The solenoid valve will provide a “push” to the spark.
d. The electrodes automatically move to put spark in pathway.

A

b. Air from the fan will blow the spark into the path.

47
Q

(620) Which action should follow an air or oil pressure adjustment?
a. Flue gas analysis.
b. Seasonal shutdown.
c. Nozzle spray check.
d. Pre-operational inspection.

A

a. Flue gas analysis.

48
Q

(621) How do commercial burners vary their firing rate?
a. Pneumatically only.
b. Decreasing water supply.
c. Electrically or electronically according to the load demand.
d. Electrically or electronically according to the outlet temperatures.

A

c. Electrically or electronically according to the load demand.

49
Q

(622) Why should you not use photocells to detect gas flames?
a. Liquefied petroleum gas (LPG) is too heavy of a gas and “fogs up” the photocell.
b. Because a well-adjusted gas flame emits too little visible light.
c. Gas flames are too dangerous to be used around photocells.
d. Natural gas corrodes the photocell.

A

b. Because a well-adjusted gas flame emits too little visible light.

50
Q

(622) How does a cad cell detect light from an oil flame?
a. Light-sensitive lead.
b. Light-sensitive cadmium sulfide.
c. Light-sensitive aluminum.
d. Light-resistive aluminum sulfide.

A

b. Light-sensitive cadmium sulfide.

51
Q

(622) A factor the flame rod system depend upon is the
a. fuel oil’s viscosity.
b. solenoids ability to conduct current.
c. flames ability to conduct current when an electrical potential is applied across it.
d. flames ability to increase resistance when an electrical potential is applied across it.

A

c. flames ability to conduct current when an electrical potential is applied across it.

52
Q

(623) The purpose of the preignition function is to ensure
a. a spark before prepurge.
b. there is an arc when the blower starts.
c. there is an arc when the oil starts to flow.
d. there is an arc when the oil stops flowing.

A

c. there is an arc when the oil starts to flow.

53
Q

(624) What is a common cause of overheating the heat exchanger on a gas fired burner?
a. The blower not running.
b. Thermostat problems.
c. Low fire conditions.
d. Proper air flow.

A

a. The blower not running.

54
Q

(625) Identify the purpose of the draft hood.
a. Make up for force of air the blower cannot create.
b. Maintain constant head on the combustion system.
c. Prevent a constant head on the combustion system.
d. Maintain fluctuating head on the combustion system.

A

b. Maintain constant head on the combustion system.

55
Q

(625) Which device(s) creates the resistance that blowers must overcome?
a. Pilot piping.
b. Solenoid valves.
c. Combination gas valves.
d. Furnace air passageways, filters, and ductwork.

A

d. Furnace air passageways, filters, and ductwork.

56
Q

(625) Where does return air enter on an upflow furnace?
a. Inside the combustion chamber.
b. Through the top of the blower compartment.
c. Through the top or side of the blower compartment.
d. Through the bottom or side of the blower compartment.

A

d. Through the bottom or side of the blower compartment.

57
Q

(625) Negative pressure is corrected in a well-sealed building by installing
a. another combustion fan.
b. a negative pressure kit.
c. an additional blower.
d. a make-up air unit.

A

d. a make-up air unit.

58
Q

(626) How is the furnace fan control connected with the blower motor?
a. Induction.
b. In series.
c. In parallel.
d. Magnetic field.

A

b. In series.

59
Q

(627) When the thermostat is turned down past the ambient temperatures the burner should
a. enter ignition carryover.
b. start trial for ignition.
c. turn on.
d. shut off.

A

d. shut off.

60
Q

(627) Which action is the first step in checking the safety limit control?
a. Turn power OFF and disconnect the blower circuit.
b. Turn power OFF and connect the blower circuit.
c. Turn power ON and connect the blower circuit.
d. Turn power ON and disconnect the blower circuit.

A

a. Turn power OFF and disconnect the blower circuit.

61
Q

(628) Which type of control is not usually located on the radiant heater?
a. Air pressure switch.
b. Ignition control.
c. Transformer.
d. Thermostat.

A

d. Thermostat.

62
Q

(629) Which inspection process is performed after the radiant heater pre-operational inspection?
a. Safety check.
b. Gas line check.
c. Gases in the air.
d. Operational test.

A

d. Operational test.

63
Q

(629) How many seconds should the thermostat be turned off to take the system out of lockout?
a. 20.
b. 60.
c. 80.
d. 90.

A

b. 60.

64
Q

(630) What should be done before making any thermostat adjustments for a forced air furnace?
a. Ensure the blower functions properly.
b. Ensure bearings are not overheating.
c. Ensure no exposure from heat or too cold from windows, doors or drafts.
d. Ensure there is a lot of exposure from heat or too cold from windows, doors or drafts.

A

c. Ensure no exposure from heat or too cold from windows, doors or drafts.

65
Q

(630) The fan’s OFF temperature setting is generally set for how many degrees above the desired room temperature
a. 0 to 5° F.
b. 3 to 5° F.
c. 5 to 10° F.
d. 15 to 20° F above.

A

c. 5 to 10° F.

66
Q

(630) If you need to remove soot from the heat exchanger, what would you use?
a. Your hands.
b. Garden hose.
c. Vacuum cleaner.
d. Pressure washer.

A

c. Vacuum cleaner.

67
Q

(631) How is a radiant heater’s combustion air intake inspected?
a. Disconnect air intake and inspect internally using a flashlight.
b. Connect vent pipe and inspect externally using a flashlight.
c. Disconnect air intake and inspect externally for weight.
d. Connect air intake and inspect internally using a level.

A

a. Disconnect air intake and inspect internally using a flashlight.

68
Q

(632) Which effect does an increase in pressure have on the boiling point?
a. It decreases it.
b. It cuts it in half.
c. It increases it.
d. It keeps it the same.

A

c. It increases it.

69
Q

(632) Which formula is correct when you need to determine the temperature of water in a steam boiler?
a. psi x 14 + 98.
b. psi x 14 + 199.
c. square root of the psi x 14 + 198.
d. square root of the psi x 18 + 298.

A

c. square root of the psi x 14 + 198.

70
Q

(633) Where is the internal feed pipe located in a steam boiler?
a. Out of the water space near, but not touching, the bottom of the steam drum.
b. Out of the water space near, but not touching, the top of the steam drum.
c. In the water space near, but not touching, the bottom of the steam drum.
d. In the water space near, but not touching, the top of the steam drum.

A

c. In the water space near, but not touching, the bottom of the steam drum.

71
Q

(634) What must the mechanical draft systems overcome?
a. Gas pressure.
b. Oil pressure.
c. All draft losses.
d. Close gas valves.

A

c. All draft losses.

72
Q

(635) Water-hammer is avoided in the piping system by using
a. flashtanks.
b. globe valves.
c. tandem valves.
d. blowdown valves.

A

a. flashtanks.

73
Q

(635) What does the probe-type low water cutoff depend on to operate?
a. Steam.
b. The Seebeck effect.
c. The flow of oil in its gears.
d. The flow of a low electrical current.

A

d. The flow of a low electrical current.

74
Q

(636) Feedwater attaches to discharge below the boiler water line so it
a. can be drained quicker.
b. disturbs normal water circulation.
c. increases the heat load on the boiler.
d. doesn’t disturb normal water circulation.

A

d. doesn’t disturb normal water circulation.

75
Q

(636) The check valve location is in the feed line
a. near the drain.
b. near the boiler.
c. near the radiators.
d. near the gas main.

A

b. near the boiler.

76
Q

(637) Why are condensate returns necessary?
a. To keep surge tanks 100% full.
b. Because some steam converts back to water.
c. To provide hot condensate for heating systems.
d. Because steam would never condense without them.

A

b. Because some steam converts back to water.

77
Q

(638) Thermostatic traps react to a difference in
a. volume between steam and fuel oil.
b. current between steam and condensate.
c. pressure between steam and condensate.
d. temperature between steam and condensate.

A

d. temperature between steam and condensate.

78
Q

(638) Condensate is subcooled in a thermostatic trap by allowing
a. no condensate to stay in the trap.
b. it to back up in the trap and a portion of the upstream drip leg piping.
c. it to back up in the radiator and a portion of the upstream drip leg piping.
d. it to back up in the radiator and a portion of the downstream drip leg piping.

A

b. it to back up in the trap and a portion of the upstream drip leg piping.

79
Q

(638) Which action does condensate trapped in a coil prevent?
a. Steam in the surge tank.
b. Even steam distribution.
c. The burner from firing.
d. Condensate from heating radiators.

A

b. Even steam distribution.

80
Q

(639) Which return water temperatures are condensing boilers designed to support?
a. Low.
b. High.
c. Ultra-low.
d. Ultra-high.

A

a. Low.

81
Q

(639) Why are the internal parts and stack of a condensing boiler constructed of corrosion resistant material?
a. Because condensing boilers are smaller.
b. Because of the paints used with these boilers.
c. Because the condensation can become corrosive.
d. The burners with these boilers create corrosive gases.

A

c. Because the condensation can become corrosive.

82
Q

(640) Why are make-up water requirements low in a closed boiler system?
a. It is vented to the atmosphere.
b. The water is open to the atmosphere.
c. The water circulates in the closed system.
d. Closed boilers never need make-up water.

A

c. The water circulates in the closed system.

83
Q

(640) Which characteristic affects the amount of water that flows through a pressure regulator?
a. Pipe length.
b. Stack length.
c. Spring tension.
d. Burner efficiency.

A

c. Spring tension.

84
Q

(640) Identify the proper position of bypass valves during normal operation.
a. 25% open.
b. 50% open.
c. 100% open.
d. Closed.

A

d. Closed.

85
Q

(641) The action that will happen to the safety relief valve if the boiler and system rises above the set pressure of the valve is it will
a. open.
b. close 25%.
c. close 50%.
d. close 100%.

A

a. open.

86
Q

(641) Identify the relationship between an aquastat’s pump control and cool water on a boiler.
a. The control prevents the circulation of any water.
b. The control prevents the circulation of hot water.
c. The control increases the circulation of cool water.
d. The control prevents the circulation of cool water.

A

d. The control prevents the circulation of cool water.

87
Q

(641) Which connection prevents air and gases that are released from the heated water in the boiler, from entering the distribution system?
a. Steam traps.
b. The diptube.
c. The drain valve.
d. The blowdown valve.

A

b. The diptube.

88
Q

(642) Which device operates the switch that stops power to the main burner on a float-type low water cutoff?
a. Float.
b. Probe.
c. Thermistor.
d. Thermocouple.

A

a. Float.

89
Q

(642) Which device does a hot water system use to handle the expansion and contraction of water?
a. Blowdown valve.
b. Expansion valve.
c. Expansion tank.
d. Check valves.

A

c. Expansion tank.

90
Q

(643) Which type of tests should water gauge glasses be checked for during a pre-operational inspection?
a. Insulation.
b. Ensure they are muddied and dirty.
c. Hit glass with hammer to test its strength.
d. Clear visibility of the gauge glasses from the operating floor.

A

d. Clear visibility of the gauge glasses from the operating floor.

91
Q

(644) Which position should the inlet and outlet valves of the circulators be in when filling a boiler system?
a. Open.
b. Closed.
c. 30% open.
d. Remove these valves while filling the boiler.

A

a. Open.

92
Q

(645) Identify what must be done if an expansion tank loses its air cushion.
a. The tank must be charged.
b. It must be filled 100% with air.
c. It should be placed in a vacuum.
d. It must be filled 100% with water.

A

a. The tank must be charged.

93
Q

(645) How is only the water level raised in an expansion tank?
a. Open the air vent valve until desired water level is obtained.
b. Open the blowdown valve until desired water level is obtained.
c. Close the air vent valve until desired water level is obtained.
d. Open the safety relief valve until desired water level is obtained.

A

a. Open the air vent valve until desired water level is obtained.

94
Q

(646) How is diesel fuel supplied to the combustion chamber on a WH–400 system?
a. Venturi action.
b. Manual hand valve.
c. A belt driven fuel pump.
d. A motor-driven fuel pump.

A

d. A motor-driven fuel pump.

95
Q

(647) How is the fuel mist ignited in a WH–400 system?
a. Sparks from the electrodes.
b. The BCU lights the mist with 120 volts.
c. The HCU lights the mist with 120 volts.
d. Sparks from the solenoid valve and HCU.

A

a. Sparks from the electrodes.

96
Q

(648) When will the heat control switch (HCU) energize the fuel burner motor and spark igniter on 130K heater?
a. After a 15 second delay.
b. After a 15 minute delay.
c. If sensor temperature is higher than programmed value.
d. If sensor temperature is lower than programmed value.

A

d. If sensor temperature is lower than programmed value.

97
Q

(648) Identify what the burner control unit do after ignition on a 130K heater.
a. Monitors combustion through a photocell.
b. Immediately initiates post purge.
c. Immediately initiates pre purge.
d. A 35 second safety recycle.

A

a. Monitors combustion through a photocell.

98
Q

(649) Identify the maximum circuit breaker size for a 130K heater.
a. 3A.
b. 15A.
c. 20A.
d. 35A.

A

c. 20A.

99
Q

(649) When does the “protective overheating switch-off” occur on a 130K heater?
a. When combustion won’t start.
b. When air flows freely in ducts.
c. When fuel solenoid valve is stuck closed.
d. When airflow is blocked by kinked ducts or blocked main air blower intake.

A

d. When airflow is blocked by kinked ducts or blocked main air blower intake.

100
Q

(649) Which state will occur if the burner control unit (BCU) locks out and is reset three times during the same burner cycle on a 130K heater?
a. Lock-up.
b. Latch-up.
c. Closed-up.
d. Opened-up.

A

b. Latch-up.

HVAC CDC's (5 decks)

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