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Mine Rescue Training > BG4 Parts And Functions Summary > Flashcards

BG4 Parts And Functions Summary Flashcards

1
Q

What is the BG4?

A

A self-contained closed-circuit, oxygen (O2) breathing apparatus that allows the wearer to work in an irrespirable atmosphere for up to four hours.

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2
Q

What type of pressure does the BG4 use?

A

Positive pressure apparatus.

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3
Q

How long can the BG4 allow a wearer to work in an irrespirable atmosphere?

A

Up to four hours.

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4
Q

What are the four major systems of the BG4?

A
  • Pneumatics
  • Breathing loop
  • Electronics
  • Backplate and harness assembly
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5
Q

What does the fully charged steel O2 cylinder provide?

A

400 litres of O2 at a pressure of 200 bar.

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6
Q

What is the purpose of the O2 pressure reducer?

A

Reduces high pressure O2 from the oxygen cylinder into medium pressure O2.

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7
Q

What is the constant dosage of O2 supplied to the breathing loop?

A

1.5 to 1.9 L/min.

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8
Q

What happens when excessive breathing demand occurs?

A

Additional medium pressure O2 is supplied to the breathing loop by the minimum (demand) valve.

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9
Q

What is the rate at which the manually operated by-pass valve injects O2 into the breathing loop?

A

50 L/min.

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10
Q

How is carbon dioxide (CO2) removed from exhaled air?

A

Using soda lime located in the refillable CO2 scrubber canister.

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11
Q

What effect does the scrubbing process have on inhaled air?

A

It produces heat which increases the temperature of inhaled air.

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12
Q

What is used to cool the heated air before inhalation?

A

An air cooler that uses ice.

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13
Q

What helps ensure low breathing resistance in the BG4?

A
  • Cooled air
  • Larger diameter breathing hoses
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14
Q

What occurs if the breathing loop becomes over pressurized?

A

A pressure relief valve vents exhaled air.

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15
Q

How is accumulated moisture released from the breathing loop?

A

Via the moisture relief valve.

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16
Q

What does the electronic monitoring system in the BG4 comprise?

A
  • Sensor
  • Switchbox
  • Sentinel
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17
Q

What does the electronic monitoring system continuously measure?

A

The pressure in the O2 cylinder.

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18
Q

What happens when residual (low) pressure is reached in the BG4?

A

An alarm is generated.

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19
Q

What design aspect of the backplate and harness assembly enhances wearer comfort?

A

Ergonomic design.

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20
Q

What do quick connect latches and easy adjust straps reduce?

A

The amount of time and energy the wearer must expend in donning and doffing the apparatus.

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21
Q

What is the main function of the Sentinel?

A

To provide information to the wearer regarding O2 cylinder pressure, time until low pressure alarm, high pressure leak test results, battery test results, low pressure alarms, and no pressure warning.

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22
Q

What does the Sentinel indicate regarding O2 cylinder pressure?

A

It indicates the current O2 cylinder pressure.

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23
Q

What does the Sentinel display about time?

A

It displays the time remaining until the first low pressure alarm.

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24
Q

What does the Sentinel indicate about the high pressure leak test?

A

It indicates the results of the high pressure leak test.

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25
Q

What does the Sentinel provide information on regarding the battery?

A

It indicates the results of the battery test.

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26
Q

What type of alarms does the Sentinel provide?

A

It provides low pressure alarms and a no pressure warning.

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27
Q

At what pressure does the first low pressure alarm activate?

A

55 bar.

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28
Q

What occurs during the first low pressure alarm at 55 bar?

A

The Sentinel beeps intermittently for 30 seconds and red LEDs flash.

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29
Q

At what pressure does the second low pressure alarm activate?

A

10 bar.

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30
Q

What happens during the second low pressure alarm at 10 bar?

A

The Sentinel beeps continuously and the red LEDs flash until it switches off.

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31
Q

What does the no pressure warning indicate?

A

It indicates that the O2 cylinder is closed or empty.

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32
Q

What pressure level triggers the no pressure warning?

A

<1.40 mbar.

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33
Q

What sound does the Sentinel make for the no pressure warning?

A

It beeps once.

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34
Q

What visual indication accompanies the no pressure warning?

A

The red LEDs flash.

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35
Q

What is the function of the pressure relief valve?

A

Prevents over-pressurization of the breathing loop.

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36
Q

Where is the pressure relief valve mounted?

A

Physically mounted to the frame of the BG4 at the breathing bag.

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37
Q

How does excess air exit the breathing loop?

A

Routed from the breathing loop at the scrubber canister along a clear tube to the valve.

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38
Q

What happens when there is too much air in the breathing loop?

A

The breathing bag over-inflates, pushing the pressure plate against the relief valve tappet.

39
Q

At what pressure range does the pressure relief valve open?

A

Between 2.0 and 5.0 millibars (mbar).

40
Q

What is the consequence of the pressure relief valve opening?

A

Expels the excess air into the atmosphere.

41
Q

Which components of the pressure relief valve are interchangeable?

A

Internal components with those of the moisture relief valve.

42
Q

What connects the Pressure Relief Valve to the Switchbox?

A

A blue line.

43
Q

Fill in the blank: The pressure relief valve is part of the _______.

A

[breathing loop]

44
Q

What is the function of the O2 pressure reducer?

A

Distributes high and medium pressure O2 to the breathing loop

The O2 pressure reducer is crucial for regulating oxygen flow and pressure in breathing apparatus.

45
Q

What activates the electronics of the O2 pressure reducer?

A

High pressure from the O2 cylinder

This activation is essential for the proper functioning of the breathing system.

46
Q

What is the medium pressure output range of the O2 pressure reducer?

A

4.0 bar to 4.4 bar

This range is vital for maintaining safe and effective oxygen delivery.

47
Q

At what pressure does the relief valve activate in the O2 pressure reducer?

A

6.0 bar

This prevents over pressurization, ensuring safety during operation.

48
Q

What is the flow rate of O2 replaced from the breathing loop under normal operation?

A

1.5 to 1.9 L/min

This constant dosage is important for maintaining adequate oxygen levels.

49
Q

What happens when the minimum (demand) valve is activated?

A

Medium pressure O2 is supplied to the valve at a flow rate of 80 L/min

This allows for increased oxygen delivery when needed.

50
Q

What flow rate does the manually operated by-pass valve inject O2 into the breathing loop?

A

50 L/min

This feature provides an additional oxygen supply when required.

51
Q

How is the O2 pressure reducer connected to the O2 cylinder?

A

By a hand-tightened connector

This ensures a secure and leak-free connection.

52
Q

Where is the minimum valve located?

A

On the right side of the breathing bag

53
Q

What triggers the activation of the minimum valve?

A

Breathing loop pressure drops to between 0.1 and 2.5 mbar

54
Q

What happens when the minimum valve is activated?

A

Injects additional O2 into the breathing loop

55
Q

What causes pressure drop in the breathing loop?

A

Excessive breathing demand or a leak in the system

56
Q

How much O2 does the minimum valve provide to the breathing loop?

A

Approximately 80 L/min

57
Q

What color is the medium pressure O2 line connecting the minimum valve to the O2 pressure reducer?

A

Yellow

58
Q

Which component is connected to the constant dosage metering orifice via a blue medium pressure O2 line?

A

Air cooler

59
Q

What does the clear line connect in the system?

A

Pressure Relief Valve to the Switchbox

60
Q

Fill in the blank: A clear O2 line joins the manually operated bypass valve to the ______ in the O2 pressure reducer.

A

constant dosage metering orifice

61
Q

What colors of lines carry O2 from the pressure reducer to various components of the BG4?

A

Yellow, blue, and clear

62
Q

What is the function of the breathing bag assembly in the BG4?

A

Holds the breathing bag in place with a retaining bar

The breathing bag assembly includes essential components for maintaining a proper breathing environment.

63
Q

What components are attached to the breathing bag?

A
  • CO2 scrubber canister
  • Air cooler
  • Minimum valve
  • Moisture relief valve

These components work together to regulate the air quality within the breathing loop.

64
Q

What is the capacity of the breathing bag?

A

5.5 litres

The breathing bag is designed to accommodate a significant volume of air for breathing.

65
Q

What material is the breathing bag made from?

A

Yellow puncture-resistant polyurethane

This material is chosen for its durability and resistance to punctures.

66
Q

How does the breathing bag generate positive pressure?

A

With the aid of two large springs

The springs assist in maintaining airflow throughout the breathing loop.

67
Q

What components make up the breathing bag assembly?

A
  • Two springs
  • Pressure plate
  • Breathing bag

These components work together to ensure effective breathing mechanics.

68
Q

Where is the pressure relief valve mounted?

A

Physically mounted to the frame of the BG4 at the breathing bag

Its location is critical for monitoring and controlling pressure within the breathing loop.

69
Q

What is the purpose of the pressure relief valve?

A

Prevents over-pressurization of the breathing loop

This is vital to ensure the safety and functionality of the breathing system.

70
Q

What happens when too much air enters the breathing loop?

A

The breathing bag over-inflates, pushing the pressure plate against the relief valve tappet

This action opens the valve to expel excess air into the atmosphere.

71
Q

At what pressure does the pressure relief valve open?

A

Between 2.0 and 5.0 millibars (mbar)

This pressure range is crucial for maintaining optimal operation of the breathing bag.

72
Q

Are the internal components of the pressure relief valve interchangeable with any other valve?

A

Yes, with those of the moisture relief valve

This interchangeability allows for easier maintenance and repairs.

73
Q

What connects the Pressure Relief Valve to the Switchbox?

A

A blue line

This connection integrates the breathing loop with the electronic control system.

74
Q

What is the function of the moisture relief valve?

A

Drains moisture that accumulates in the breathing bag

The valve activates when the pressure in the moisture trap is between 15 - 25 millibars (mbar) and drains moisture into the atmosphere.

75
Q

Where is the moisture relief valve located?

A

At the bottom of the breathing bag

It is attached to the frame of the BG4 with a retaining clip.

76
Q

What prevents soda lime particles from entering the moisture relief valve?

A

A sintering filter

The filter is located at the top of the valve housing.

77
Q

True or False: The internal components of the moisture relief valve are interchangeable with those of the pressure relief valve.

A

True

78
Q

What is the purpose of the air cooler in the breathing loop?

A

Lowers the temperature of the inhaled breathing air

This reduces the physical strain on the wearer.

79
Q

Where is the air cooler located in relation to the breathing bag and inhalation hose?

A

Between the breathing bag and the inhalation hose

It is secured to the frame by a roller clamp.

80
Q

What type of system enriches the breathing loop with O2 at the air cooler?

A

Constant dosage system

81
Q

Fill in the blank: The air cooler is a simple _______ that helps regulate the temperature of inhaled air.

A

[heat exchanger]

82
Q

What is the connection method between the air cooler and the inhalation hose?

A

Quarter turn bayonet ring

83
Q

What feature of the ice chamber prevents condensate and melted ice from entering the body of the BG4?

A

Cover on the ice chamber

84
Q

How is the air cooler attached to the breathing bag?

A

Sleeve and collar connection

85
Q

What are the molding seams on the hose connection used for?

A

Ensure proper alignment with the inhalation hose during assembly

86
Q

What happens to the air cooler when filled with preformed ice?

A

Lowers the temperature of the inhaled breathing air

87
Q

What is the breathing rate mentioned in the text?

A

30 L/min

88
Q

At what ambient temperature can the breathing air temperature be maintained below 37°C?

A

24°C (75°F)

89
Q

For how long can the breathing air temperature be maintained below 37°C?

A

Up to 4 hours

90
Q

What factors affect how long the ice lasts and the air cooler remains effective?

A

Air temperature and breathing rate

91
Q

What will reduce available service time for the ice packs?

A

Ice packs which are small, broken up or not completely frozen

92
Q

What temperature can the breathing air rise above if ice packs are not effective?

A

37°C (98°F)

93
Q

What modification is required for the BG4 Plus air cooler?

A

Must be modified to fit into the older BG4

Mine Rescue Training (16 decks)

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