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Volume 4 Environmental Control Systems > URE Questions > Flashcards

URE Questions Flashcards

1
Q

Refrigeration is the process of

A. Adding a cold substance to eliminate heat.
B. Removing heat from where it is not wanted.
C. Circulating a substance to absorb heat intensity.
D. Varying the density of heat to ensure heat transfer.

A

B. Removing heat from where it is not wanted.

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2
Q

Heat intensity indicates

A. The speed of the molecules in a substance.
B. The amount of heat something can contain.
C. How many British thermal units are present.
D. How much heat is required to liquefy a substance.

A

A. The speed of the molecules in a substance.

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3
Q

Heat will transfer from a hotter substance to a colder substance until

A. Electrical energy is moved.
B. All molecules are moving at the same speed.
C. Molecular movement stops completely at absolute zero.
D. The pressure in a system is removed and it slowly drops.

A

B. All molecules are moving at the same speed.

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4
Q

If a gauge reading indicates 10 pounds per square inch gauge (psig), this means

A. Atmospheric pressure is 10 psig.
B. The pressure is 10 psig above atmospheric pressure.
C. The pressure is 4.7 psig below atmospheric pressure.
D. The system pressure and atmospheric pressure together is 10 psig

A

B. The pressure is 10 psig above atmospheric pressure.

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5
Q

What personal protective equipment must be worn whenever exposure to liquid refrigerant is possible?

A. Leather gloves only.
B. Splash-proof goggles and rubber goggles.
C. Splash-proof goggles and leather gloves.
D. Impact goggles, rubber gloves, and rubber apron.

A

C. Splash-proof goggles and leather gloves

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6
Q

Why would we need a refrigerant to be stable?

A. We must be able to pinpoint and repair large leaks.
B. The condensing pressures in the system are too low.
C. It is constantly changing states throughout the system
D. It could deteriorate the inside of the refrigerant system.

A

C. It is constantly changing states throughout the system.

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7
Q

What can happen if the refrigerant R-22 mixes with moisture in the refrigerant system?

A. It will cause the oil and refrigerant to separate.
B. It will leak through gasket joints installed in the system.
C. Hydrochloric acid could cause compressor motor to burnout.
D. The refrigerant will leak out when the moisture is removed.

A

C. Hydronic acid could cause compressor motor to burnout

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8
Q

When heat is transferred by conduction, the heat is transferred by

A. Direct contact
B. Movement of air or liquid
C. The movement of electricity
D. Waves from a central source

A

A. Direct contact

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9
Q

When the substance is in the process of changing states, what happens to the substances temp?

A. The temp remains the same as latent heat is transferred.
B. The temp remains the same as sensible heat is transferred.
C. The temp increases until all of the substance has changed state.
D. The temp decreases until all of the substance has changed state.

A

A. The temp remains the same as latent heat his transferred.

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10
Q

What action takes place at the condensing point in the brine chiller’s condenser?

A. The refrigerant begins turning into a gas.
B. The refrigerant begins turning into a liquid.
C. All of the refrigerant has turned into a gas.
D. All of the refrigerant had turned into a liquid.

A

B. The refrigerant begins turning into a liquid.

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11
Q

What slowly takes place as the refrigerant travels between the condenser and expansion valve?

A. Saturation
B. Subcooling
C. Superheating
D. Desuperheating

A

B. Subcooling

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12
Q

The refrigerant leaving the evaporator is

A. A low-pressure/low-temperature gas.
B. A low-pressure/low-temperature liquid.
C. A high-pressure/high-temperature gas.
D. A high-pressure/high-temperature liquid.

A

A. A low-pressure/low temperature gas.

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13
Q

What heat transfer process is taking place in the brine chiller’s condenser?

A. Air-to-brine heat transfer.
B. Refrigerant-to-Air heat transfer.
C. Air-to-refrigerant heat transfer.
D. Brine-to-refrigerant heat transfer.

A

B. Refrigerant-to-Air heat transfer.

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14
Q

A refrigerant compressor is considered hermetic if

A. The compressor operates from the rotary motion of a motor pulley attached to a a lever mechanism.
B. The motor and compressor are contained in one shell, but the internal components can be repaired.
C. The motor and compressor are contained in one shell, and the internal components cannot be accessed.
D. The motor and the compressor are separated, and the compressor operates from a belt attached to the motor.

A

C. The motor and compressor are contained in one shell, and the internal components cannot be accessed.

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15
Q

In a scroll compressor, what happens to the refrigerant once it reaches the center of the stationary scroll?

A. The gaseous refrigerant is discharged through the discharge port.
B. Crescent shaped pockets are made smaller compressing the refrigerant.
C. The liquid refrigerant is compressed by the two scrolls coming together.
D. The suction of the compressor creates a vacuum rotating the orbital scroll.

A

A. The gaseous refrigerant is discharged through the discharge port.

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16
Q

What would happen if the air temperature across the refrigerant condenser is high?

A. Heat transfer will increase as the temperature equalizes.
B. The expansion valve will open fully bypassing the condenser.
C. The refrigerant will vaporize faster due to latent heat of condensation.
D. Heat transfer will decrease as it approaches the temperature of the refrigerant.

A

D. Heat transfer will decrease as it approaches the temperature of the refrigerant.

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17
Q

Having a heat exchanger on the refrigerant condenser ensures

A. Refrigerant vaporizes before the filter-drier.
B. Gaseous refrigerant enters the receiver tank.
C. Only liquid refrigerant leaves the condenser.
D. The superheat is sufficient entering the compressor.

A

C. Only liquid refrigerant leaves the condenser

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18
Q

What is the main advantage of the safety relief valve over the rupture disk in providing pressure relief to the refrigerant system?

A. The rupture disk only operates off refrigerant temperature.
B. The rupture disk contains lead and is difficult to dispose of.
C. The safety relief valve will close when the overpressure is released.
D. The safety relief valve will vent all refrigerant protecting the system.

A

C. The safety relief valve will close when the overpressure is released.

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19
Q

The moisture indicator sight glass will indicate the system is operating normally, free of moisture, if the sight glass is

A. Clear with a green dot in the center.
B. Clear with a black dot in the center.
C. Cloudy with a green dot in the center.
D. Cloudy with a black dot in the center.

A

A. Clear with a green dot in the center.

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20
Q

How does the equalizer line keep the thermostatic expansion valve (TXV) from flooding and starving the evaporator for refrigerant.

A. The equalizer line forces the TXV spring to make small corrections instead of drastic ones.
B. The TXV balances equalizer pressure with thermal bulb expansions to fully open or fully close.
C. The equalizer line balances the refrigerant entering the TXV to the refrigerant leaving the TXV.
D. It monitors the latent heat of vaporization and balances it against the subcooling for a steady flow.

A

A. The equalizer line forces the TXV spring to make small corrections instead of drastic ones.

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21
Q

What would cause the programmable logic controller (PLC) to shut down the brine chiller in an emergency?

A. Refrigerant discharge pressure exceeds 370 pounds per square inch gauge (psig).
B. Refrigerant superheat exceeds 8 degrees Fahrenheit.
C. Refrigerant evaporator pressure falls to 200 psig.
D. Refrigerant suction pressure falls to 20 psig.

A

A. Refrigerant discharge pressure exceeds 370 pounds per square inch gauge (psig).

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22
Q

Why is the compound manifold gauge assembly (MGA) connected to the low side of the system?

A. To see if the discharge pressure is creating a vacuum
B. To see if the compressor is drawing the system into a vacuum
C. The evaporator pressures will be displayed as subcooling on the gauge.
D. The pressures on the low side of the system are too low for a high-pressure gauge.

A

B. To see if the compressor is drawing the system into a vacuum.

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23
Q

What action must you take before zeroing the gauges on a manifold gauge assembly (MGA)?

A. Purge contaminants
B. Ensure the hoses are disconnected
C. Connect it to the suction side of the system.
D. Verify the gauge has been previously calibrated.

A

B. Ensure the hoses are disconnected.

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24
Q

When purging contaminants from the manifold and gauge assembly (MGA) hoses, when you open the valve on the receiver tank, the

A. Refrigerant in the receiver tank forces contaminants out of the hoses.
B. Receiver tank draws the hoses into a cabin removing the contaminants.
C. Vacuum in the refrigerant system forces contaminants into the receiver tank.
D. Refrigerant from the system flushes the hoses when the calves are back seated.

A

B. receiver tank draws the hose into a vacuum removing the contaminants.

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25
Q

Once the electronic leak detector has stabilized, the leak detector is passed along the refrigerant lines at

A. 1 inch per second, keeping the probe tip 1/4 inch from the surface.
B. 2 inch per second, keeping the probe tip 1 inch from the surface.
C. 3 inch per second, keeping the probe tip 1 3/4 inch from the surface.
D. 4 inch per second, keeping the probe tip 2 1/4 inch from the surface.

A

A. 1 inch per second, keeping the probe tip 1/4 inch from the surface.

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26
Q

When using a nitrogen bottle and regulator to check for leaks in a refrigerant system, a leak is indicated if

A. 300 pounds per square inch gauge (psig) of pressure holds for at least two hours.
B. 300 psig of pressure holds for at least one hour.
C. You lose 2 psig of pressure in an hour, with the regulator off.
D. You lose 2 psig of pressure in two hours with the regulator on.

A

C. You lose 2 psig of pressure in an hour, with the regulator off.

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27
Q

How does a gauge tube cause a display on the micron gauge?

A. The vacuum level is converted into an electrical signal.
B. The electrical pulses indicate positive pressure on the diaphragm.
C. The vacuum passes through the tube and causes bellow movement.
D. The bellow’s movement of the gauge tube causes the vacuum to display.

A

A. The vacuum level is converted into an electrical signal.

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28
Q

How are the switches on the gas detector selected when using the gas calibrator kit?

A. Remotely, by the missile combat crew.
B. Remotely, using the pressure regulator.
C. By pressing the buttons with your fingers.
D. By touching a magnetic stick to the button.

A

D. By touching a magnetic stick to the button.

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29
Q

In order for the gas detector to display the proper reading for the correct level of lower explosive limit (LEL), it must be calibrated to know what

A. The LEL alarm threshold should be.
B. Types of gasses that create high-level LEL.
C. 0 percent LEL and 50 percent LEL looks like.
D. 0 percent LEL and 100 percent LEL looks like.

A

C. 0 percent LEL and 50 percent LEL looks like.

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30
Q

A digital manometer measures static pressure by

A. Comparing static pressure to absolute pressure.
B. Sensing the pressure difference between two points.
C. Displaying both inches of water and inches of mercury.
D. Indicating how far below atmospheric pressure a reading is.

A

B. Sensing the pressure difference between two points.

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31
Q

When using the wet/dry manometer, you tighten the hoses between the manometer and the brine flow Venturi valves when

A. The required reading is obtained.
B. Liquid brine starts escaping the hoses.
C. Connecting them to the flow venturi valves.
D. The pressure reading needs to be smoothed out.

A

B. Liquid brine starts escaping the hoses.

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32
Q

Why is the use of a thermometer unnecessary when using the temperature control test set?

A. The temperature display is calibrated.
B. The temperature display is an approximation.
C. There is no place to put a thermometer probe.
D. The system will have displayed the temperature.

A

A. The temperature display is calibrated.

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33
Q

When is the temperature in the temperature control test set (TCTS) well considered stable?

A. When the set temperature is reached.
B. 6 minutes after reaching the set temperature.
C. 60 minutes after reaching the set temperature.
D. When deflection meter stabilizes in the center.

A

B. 6 minutes after reaching the set temperature.

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34
Q

Why is a light source needed with the fiber-optic test set?

A. The light source sets the fiber-optic repeater source as a reference reading.
B. An additional light source boosts the fiber-optic signal traveling through the cable.
C. The power meter measures the impedance between a good signal and a bad signal.
D. There is no light traveling through the cables to be tested with the system de-energized.

A

D. There is no light traveling through the cables to be tested with the system de-energized.

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35
Q

What precaution must be observed when handling or working with fiber-optic cables?

A. Never exceed a 2-inch bend radius or the glass inside the cable will break.
B. Always use infrared eye protection when working with unshielded cables.
C. Always use electrostatic discharge caps when capping fiver-optic cable ends.
D. Never attach an ST-connector to a V-pin cable or electrical shorts could result.

A

A. Never exceed a 2-inch bend radius or the glass inside the cable will break.

36
Q

When testing a fiber-optic cable, if the power meter display shows a signal loss of more than 5 decibels, what action should be taken first?

A. Verify the reading against a known-good cable to verify the meter is set up properly.
B. Boost the light source to 880 nanometers to see if the decibel loss gets higher.
C. Replace the cable and return the bad one to base for refurbishment.
D. Clean the cable ends with isopropyl alcohol and a lint-free cloth.

A

D. Clean the cable ends with isopropyl alcohol and a lint-free cloth.

37
Q

Before inserting a thermometer probe into a thermometer well in the brine system, always ensure

A. The wells are full of liquid.
B. There are no contaminants in the well.
C. The brine expansion tank valve is open.
D. Refrigerant is not circulating into the well.

A

A. The wells are full of liquid.

38
Q

What does the programmable logic controller (PLC) use to ensure a slow response instead of a rapid response causing major fluctuations in the system?

A. Analog input/output module.
B. Proportional-integral-derivative controllers.
C. The controlnet daughter-card’s node address.
D. A fiber-optic repeater adapter to slow signals.

A

B. Proportion-integral-derivative controllers.

39
Q

When replacing the controlnet daughtercard, why must the node address be set to “1”?

A. This indicates it receives commands from address “0”?
B. This indicates it is the host for the communications network.
C. To ensure communication with the programmable logic controller.
D. To enable parameters to be sen on the panel display as address “2”.

A

B. This indicates it is the host for the communication network.

40
Q

How does the programmable logic controller (PLC) know when a damper actuator has repositioned?

A. A milliamp feedback signal is returned through an analog input/output module.
B. A positioning sensor converts the voltage to amps and signals the panel display.
C. The controlnet adapter on that circuit biases the fiber-optic repeater to signal the PLC.
D. A feedback signal of 10 volts drains until the actuator has reached its desired position.

A

A. A milliamp feedback signal is returned through an analog input/output module.

41
Q

An analog feedback signal from a pressure sensor to the programmable logic controller (PLC) will be determined by the

A. Suction pressure at the refrigerant compressor.
B. Signal from a fiber-optic signal conditioner.
C. Brine flow through the brine system.
D. Amount of airflow through a duct.

A

D. Amount of airflow through a duct.

42
Q

The fiber-optic repeater adapter

A. Is the fiber-optic source for pressure sensors.
B. Extends the length of the controlnet network.
C. Is used to amplify the fiber-optic signal to a damper actuator.
D. Connects to the fiber-optic repeater via interconnecting cable.

A

B. Extends the length of the controlnet network.

43
Q

The controlnet adapter connects to the fiber-optic repeater adapter through

A. Coaxial cable.
B. Standard wiring.
C. A fiber-optic cable.
D. A back-plane connector.

A

A. Coaxial cable.

44
Q

The fiber-optic signal conditioner

A. Sends excitation light pulses to a temperature sensor.
B. Amplifies the fiber-optic signal from the controlnet daughtercard.
C. Transmits feedback signals to a damper actuator based on pressure.
D. Powers a binary input module to show a reading on the panel display.

A

A. Sends excitation light pulses to a temperature sensor.

45
Q

The condenser fan will NOT start until

A. Pressure switch (PSW)-1 closes when discharge pressure is sufficient.
B. Pressure sensor (PSR)-1 responds when conditioning airflow is sufficient.
C. Temperature switch (TSW)-1 closes when brine temperature is high enough.
D. Temperature sensor (TSR)-3 responds when conditioned air temperature is low enough.

A

A. Pressure switch (PSW)-1 closes when discharge pressure is sufficient.

46
Q

When the head pressure control calve opens at 100 pounds per square inch (PSI), refrigerant flow will bypass the

A. Compressor
B. Receiver tank
C. Condenser coils
D. Hot gas bypass valve.

A

C. Condenser coils.

47
Q

The programmable logic controller (PLC) performs a normal brine chiller shutdown by

A. De-energizing a binary input, causing the solenoid valves in the brine system to open.
B. Energizing an analog output circuit, causing the condenser fan dampers to stop airflow.
C. De-energizing a binary output, causing solenoid valves in the refrigerant system to close.
D. Energizing a binary input, signaling the air handler to shut down, stopping the brine chiller.

A

C. De-energizing a binary output, causing the solenoid valves in the refrigerant system to close.

48
Q

What is the purpose of the flow Venturi in the brine system?

A. Provide a means for a technician to check brine flow.
B. Limit the flow of brine to help control the temperature.
C. Keep the brine from freezing in the underground piping.
D. Create enough pressure for brine to travel to the air handler.

A

A. Provide a means for a technician to check brine flow.

49
Q

Brine is added to the system at the

A. Evaporator
B. Brine pump
C. Strainer valve
D. Expansion tank

A

D. Expansion tank

50
Q

The brine strainer in the brine system is designed to filter out

A. Acid
B. Moisture
C. Sediment
D. Refrigerant

A

C. Sediment

51
Q

What action occurs after the refrigerant compressor motor starter K-2 energizes?

A. The brine pump starts because K-2 X1 contacts close.
B. The low-pressure switch closes automatically to start the compressor.
C. The crankcase heater de-energizes because the K-2 X2 contacts open.
D. The hot gas bypass valve begins sending refrigerant to the condenser.

A

C. The crankcase heater de-energizes because the K-2 X2 contacts open.

52
Q

Before the programmable logic controller (PLC) will start the brine chiller, what other component must be operating?

A. Exhaust fan.
B. Launch tube heater fan.
C. Air handler motor starter.
D. Damper positioning relay.

A

C. Air handler motor starter.

53
Q

The programmable logic controller (PLC) performs a normal brine chiller shutdown if the

A. Air handler shuts down due to insufficient airflow.
B. The launch tube heater shuts down on high temperature.
C. Temperature switch (TSW)-1 opens due to high temperature.
D. Low-pressure cutout (LPC)-1 opens due to low-suction pressure.

A

A. air handler shuts down due to insufficient airflow.

54
Q

In wings 3 and 5 ventilating air subsystems, why do dampers D-14 and D-13B fully close when the room temperature is below 68 degrees Fahrenheit?

A. Allow fresh air to enter the room
B. Prevent heat from escaping the room
C. Prevent fresh air from entering the room.
D. Allow heat from the engine to enter the room

A

B. Prevent heat from escaping the room.

55
Q

In wings 3 and 5 ventilating air subsystem, why is damper D-17 closed when the room temperature is above 72 degrees?

A. Keep fresh air from entering the room
B. Maintain the Diesel engine temperature.
C. Allow heat from the brine chiller to enter the room.
D. Prevent heat from the engine from entering the room.

A

D. Prevent heat from the engine from entering the room.

56
Q

In wings 3 and 5 ventilation control panel, the exhaust fan starts automatically when the

A. Diesel run signal is sent directly to motor starter k-10
B. Lower explosive limit (LEL) is sensed to be above 45 percent.
C. Room temperature is sensed to be above 80 degrees Fahrenheit.
D. Makeup airflow is too high, causing return air to enter the room.

A

A. Diesel run signal is sent directly to motor starter K-10

57
Q

If the room heater thermostat senses the room temperature has fallen to 43 degrees Fahrenheit, it will

A. Send an alarm signal that the room is too cold.
B. Start the fan on high speed to better distribute heat.
C. Energize the first stage to help the ventilation subsystem.
D. Energize the heater’s second stage to provide additional heat.

A

D. Energize the heater’s second stage to provide additional heat.

58
Q

What air handler component is checked during periodic inspections using a manometer?

A. Pressure sensor calibration.
B. Air filter for proper airflow.
C. Fan assembly for proper rating.
D. Airflow through cooling coil dampers.

A

B. Air filter for proper airflow.

59
Q

The cooling coil bypass damper should fully close if the

A. Brine supply temperature is 35 degrees Fahrenheit.
B. Airflow to the racks is less than 0.15 inches of water (in Wg)
C. Launch tube temperature is greater than 80 degrees Fahrenheit.
D. Air temperature to the racks is greater than 57 degrees Fahrenheit.

A

D. Air temperature to the racks is greater than 57 degrees Fahrenheit.

60
Q

When the programmable logic controller (PLC) senses the k-4 motor starter energized, what other component is allowed to operate?

A. Brine chiller unit.
B. Launch tube heater fan.
C. Emergency air handler fan.
D. Exhaust fan in ventilation system.

A

A. Brine chiller unit.

61
Q

What does transformer T-2 in the air handler control panel do with its 120 volts alternating current (VAC) input?

A. Compensates for voltage drops across noise filters.
B. Steps it down to 24 CAC for use by the damper actuators.
C. Steps it down to 4 milliamp a for the combustible gas detector.
D. Converts it to 26 volts direct current (VDC) for the panel display.

A

B. Steps it down to 24 VAC for use by the damper actuators.

62
Q

How will the programmable logic controller (PLC) know the combustible gas detector has failed?

A. It will sense a 0 percent lower explosive limit (LEL)
B. The ground maintenance response (GMR)-27 will report
C. It’s signal is less than 4 milliamps for more than 300 seconds.
D. The binary output module on the gas detector will de-energize.

A

C. Its signal is less than 4 milliamps for more than 300 seconds.

63
Q

The air for the emergency air handler fan is drawn from

A. Ventilating air from the top of the launch tube.
B. Fresh air at the top of the personnel access shaft.
C. The lower level launcher equipment room (LER).
D. The makeup air system in the launcher support building (LSB).

A

C. The lower level launcher equipment room (LER).

64
Q

What powers the emergency air handler fan during its operation?

A. 24 volts alternating current (VAC) from the transformers in the panel.
B. 26 volts direct current (VDC) from the air handler control panel.
C. 120 VAC from circuit breaker in the LDB pane.
D. 32 VDC from the storage battery set.

A

D. 32 VDC from the storage battery set.

65
Q

When the system transfers normal air handler to emergency air handler operation, how are the normal and emergency isolation dampers switched for emergency operation?

A. Damper positioning relay K-8 de-energizes, allowing the dampers to reposition.
B. Damper positioning relay K-7 energizes, opening contacts to remove power from the actuators.
C. The programmable logic controller (PLC) will vary an analog signal to position them accordingly.
D. They will fully reposition with the application of voltage from the emergency air handler control panel.

A

B. Damper positioning relay K-7 energizes, opening contacts to remove power from the actuators.

66
Q

Temperature sensor (TSR)-4 will try to operate the launch tube heater coils if the launch tube temperature fell to

A. 58.5 degrees.
B. 66.5 degrees.
C. 70 degrees.
D. 75 degrees.

A

B. 66.5 degrees.

67
Q

What would occur if the temperature of the launch tube heating coils exceeded 135 degrees Fahrenheit?

A. A binary output would de-energize to signal an alarm.
B. A temperature switch would remain closed until it reaches 140 degrees Fahrenheit.
C. A binary output would de-energize to shut down the heating coils.
D. A temperature switch would open shutting down the heating coils.

A

D. A temperature switch would open shutting down the heating coils.

68
Q

In order for a ground maintenance response (GMR)-28 to report,

A. The launch tube temperature must be below 60 degrees for more than 15 seconds.
B. The launch tube temperature must be above 80 degrees for more than 30 seconds.
C. The conditioned air temperature must be below 50 degrees for more than 15 seconds.
D. The conditioned air temperature must be above 60 degrees for more than 30 seconds.

A

A. The launch tube temperature must be below 60 degrees for more than 15 seconds.

69
Q

Brine from the brine chiller unit enters the launch control center (LCC) to

A. Pickup any moisture removed from the LCC humidifier system.
B. Cycle through th emergency cooling coil during emergency mode operation.
C. Cool water in the chilled water storage tank to be used during emergency mode.
D. Cool the temperature of the air going to the racks if it exceeds 65 degrees Fahrenheit.

A

C. Cool water in the chilled water storage tank to be used during emergency mode.

70
Q

Why is more brine needed at a wing 1 missile alert facility (MAF) as compared to a wing 3 and 5 MAF?

A. The brine chiller unit at a wing 1 MAF is much larger.
B. The brine piping is longer since the brine chiller unit is topside.
C. The wing 1 heat load is larger, thus the brine expands and contracts more.
D. The refrigerant charge is higher, thus it needs more brine to keep it from freezing.

A

B. The brine piping is longer since the brine chiller unit is topside.

71
Q

In order for the missile alert facility (MAF) brine chiller to operate the

A. Air handler must be operating.
B. Supply fan must be operating.
C. Diesel engine must not be operating.
D. Personnel heat must not be operating.

A

A. Air handler must be operating.

72
Q

If the refrigerant discharge pressure is not above 140 pounds per square inch (psi) when the missile alert facility (MAF)brine chiller starts up, the

A. Brine pump will immediately shut down.
B. Refrigerant compressor will immediately shut down.
C. Supply fan will start to remove heat from the refrigerant.
D. Refrigerant will circulate until the pressure is above 140 psi.

A

D. Refrigerant will circulate until the pressure is above 140 psi.

73
Q

During a missile alert facility (MAF) normal brine chiller shutdown, the refrigerant compressor will stop operating

A. After the 10-minute pump down timer has elapsed.
B. When the suction pressure falls to 2-15 pounds per square inch (psi).
C. Immediately when the shutdown signal is noticed on the panel display.
D. When the programmable logic controller opens the binary output module.

A

B. When the suction pressure falls to 2-15 pounds per square inch (psi).

74
Q

Why does the room pressure change when the Diesel engine operates in the launch control equipment building (LCEB)?

A. It pulls the intake blast valve about 50 percent closed.
B. The air handler shuts down when the Diesel engine operates.
C. The exhaust fan will push more air out of the room than usual.
D. The makeup air fan operates on high speed and draws in more air.

A

C. The exhaust fan will push more air out of the room than usual.

75
Q

If the missile alert facility (MAF) Diesel engine is operating at 173 degrees Fahrenheit, the face damper closes and the bypass damper opens to

A. Keep air from removing heat from the radiator.
B. Balance the room pressure against the engine temperature.
C. Ensure a steady flow of air to remove heat from the coolant.
D.maintain the room temperature with Diesel engine operating.

A

A. Keep air from removing heat from the radiator.

76
Q

What two air sources are used by the missile alert facility (MAF) air handler fan?

A. Return air form the launch control equipment building (LCEB) and clean room air.
B. Return air from the launch control center (LCC) and makeup air.
C. Return air form the LCC and supply air from the intake shaft.
D. Makeup air and clean room air.

A

B. Return air form the launch control center (LCC) and makeup air.

77
Q

What is the purpose of switch (SW)-104 on the side of the air handler unit?

A. Provides lighting for the air handler intake plenum.
B. Provides a means to manually turn off the air handler.
C. Disables the clean room pressure circuit during maintenance.
D. Balances the airflow between the clean room and makeup system.

A

A. Provides lighting for the air handler intake plenum.

78
Q

What condition would NOT cause the air handler to shut down and transfer to emergency cooling unit operation?

A. Conditioned air temperature to the racks gets too high.
B. Conditioned airflow to the racks falls out of tolerance.
C. Emergency air handler switch set to HAND.
D. Clean room pressure falls out of tolerance.

A

D. Clean room pressure falls out of tolerance

79
Q

How is chilled water cycled through the emergency cooling unit in the launch control center (LCC)?

A. The brine pump in the brine chiller unit forces water through.
B. A direct current (DC) chilled water pump that starts in an emergency.
C. An alternating current (AC) chilled water pump that starts in an emergency.
D. It is gravity fed since the chilled water tank is higher than emergency cooling unit.

A

B. A direct current (DC) chilled water pump that starts in an emergency.

80
Q

How long will chilled water cool the air to the electronic racks during emergency mode operation?

A. Until the brine pump in the brine chiller unit shuts down.
B. Until all water has been cycled from the chilled water tank through the cooling coil.
C. As long as the chilled water pump is cycling water between the tank and cooling coil.,
D. As long as the chilled water pump is cycling brine between the tank and the evaporator.

A

B. Until all the water has been cycled from the chilled water tank through the cooling coil.

81
Q

If the emergency cooling unit is operating and primary power is available, the normal air handler is restored to operation when

A. The emergency cooling unit shuts down due to high temperature to the racks.
B. The condition that caused it to shut down no longer exists and the alarms rest.
C. Primary power cycles off and then on to reset the programmable logic controller.
D. Switch (SW)-106 on the emergency control panel is pressed to restart normal operation.

A

D. Switch (SW)-106 on the emergency control panel is pressed to restart normal operation.

82
Q

How does the programmable logic controller (PLC) determine what the humidity in the air to the racks is at a missile alert facility (MAF)?

A. It senses the temperature of the air leaving the cooling coil.
B. It uses an analog input/output module on the room humidifier.
C. A pressure sensor converts the humidity into a feedback signal.
D. It senses the temperature of the ambient air in the launch control center.

A

A. It senses the temperature of the air leaving the cooling coil.

83
Q

To determine the clean room pressure, a pressure sensor checks the difference in pressure between the clean room and

A. Makeup air system
B. Outside ambient air.
C. The launch control center (LCC).
D. The launch control equipment building (LCEB).

A

D. The launch control equipment building (LCEB).

84
Q

When operating the oxygen regeneration unit, the missile combat crew will know to swap out the canisters when the

A. Bell on the timer rings.
B. Sight glass shows empty.
C. Oxygen gauge on the console is low.
D. Auxiliary alarm panel shows an alarm.

A

A. Bell on the timer rings.

85
Q

Damping fluid is used in the oxygen regeneration unit for

A. Cooling the unit during operation.
B. Increase humidity of oxygen output.
C. Lubricating the hand crank and air pump.
D. Creating oxygen when it mixes with potassium.

A

C. Lubricating the hand crank and air pump.

Volume 4 Environmental Control Systems (1 decks)

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