CHAT SUP STUDY

Question 1

10 metres seawater equals how much pressure?

Answer 1

1 bar

Question 2

Formula for absolute pressure (metric)?

Answer 2

(Depth ÷ 10) + 1 = bar absolute

Question 3

33 feet seawater equals?

Answer 3

1 atmosphere (ata)

Question 4

When must absolute pressure be used?

Answer 4

Gas consumption and partial pressure calculations

Question 5

Normal diver breathing rate?

Answer 5

35 litres per minute

Question 6

Emergency diver breathing rate?

Answer 6

40 litres per minute

Question 7

Gas reclaim loss allowance?

Answer 7

5 litres per minute

Question 8

Gas consumption formula?

Answer 8

Absolute pressure × breathing rate

Question 9

Gas consumption at 30 msw (normal)?

Answer 9

4 bar × 35 = 140 l/min

Question 10

Time available formula?

Answer 10

Gas available ÷ gas consumption

Question 11

Gas volumes must be measured at what pressure?

Answer 11

Surface equivalent (free gas)

Question 12

Free gas volume formula?

Answer 12

Floodable volume × pressure

Question 13

Pressure used in free gas volume calculation?

Answer 13

Absolute pressure

Question 14

Emergency breathing rate for bail-out?

Answer 14

40 litres per minute

Question 15

Bail-out rule of thumb?

Answer 15

1 minute per 10 metres (33 feet) of umbilical

Question 16

Regulator drive pressure allowance?

Answer 16

10 bar (150 psi)

Question 17

Available pressure formula?

Answer 17

Start pressure − changeover pressure

Question 18

When is regulator drive pressure subtracted?

Answer 18

Bail-out and emergency supplies

Question 19

Dalton’s Law formula?

Answer 19

Partial pressure = absolute pressure × gas fraction

Question 20

ppO2 of air at surface?

Answer 20

0.21 bar

Question 21

Sum of all partial pressures equals?

Answer 21

Absolute pressure

Question 22

Typical working ppO2 range?

Answer 22

0.4 to 1.3 bar

Question 23

Saturation living ppO2 range?

Answer 23

0.5 to 0.8 bar

Question 24

Low oxygen partial pressure causes?

Answer 24

Hypoxia

Question 25

High oxygen partial pressure causes?

Answer 25

Oxygen toxicity

Question 26

CO2 conversion from ppm to percent?

Answer 26

ppm ÷ 10

Question 27

Acceptable chamber CO2 level?

Answer 27

Less than 5 millibar

Question 28

Charles’ Law formula?

Answer 28

P1/T1 = P2/T2

Question 29

Temperature scale used in gas laws?

Answer 29

Absolute (Kelvin or Rankine)

Question 30

Effect of cold water on gas cylinders?

Answer 30

Pressure drops

Question 31

Which law explains partial pressures?

Answer 31

Dalton’s Law

Question 32

Which law explains decompression?

Answer 32

Henry’s Law

Question 33

Which law explains temperature effects?

Answer 33

Charles’ Law

Question 34

Who has authority to stop the dive?

Answer 34

The diving supervisor

Question 35

Supervisor appointment must be?

Answer 35

Formal and in writing

Question 36

Biggest gas calculation mistake?

Answer 36

Using gauge instead of absolute pressure

Question 37

Emergency gas calculation mistake?

Answer 37

Using 35 instead of 40 litres per minute

Question 38

Hidden bail-out gas killer?

Answer 38

Cold temperature reducing pressure

Question 39

Gauge pressure vs absolute pressure?

Answer 39

Gauge excludes atmospheric pressure; absolute includes it

Question 40

Absolute pressure formula (imperial)?

Answer 40

(Depth ÷ 33) + 1 = ata

Question 41

When is gauge pressure used?

Answer 41

Quad volumes and chamber pressurisation

Question 42

When is absolute pressure mandatory?

Answer 42

Diver gas consumption and partial pressures

Question 43

Free gas volume definition?

Answer 43

Gas volume expanded to surface pressure

Question 44

Emergency gas consumption formula?

Answer 44

Absolute pressure × 40 l/min

Question 45

Normal gas consumption formula?

Answer 45

Absolute pressure × 35 l/min

Question 46

Why is emergency rate higher?

Answer 46

Cold shock and stress

Question 47

What pressure is unavailable in bail-out bottles?

Answer 47

Ambient pressure plus regulator drive pressure

Question 48

Regulator drive pressure value?

Answer 48

10 bar or 150 psi

Question 49

Bail-out time formula?

Answer 49

Available gas ÷ (absolute pressure × 40)

Question 50

Gas volume formula for cylinders?

Answer 50

Cylinder volume × pressure

Question 51

64 × 50 litre quad floodable volume?

Answer 51

3

Question 52

Free gas volume of quad formula?

Answer 52

Floodable volume × pressure

Question 53

Why are quads changed early?

Answer 53

To avoid reaching unavailable pressure

Question 54

Typical quad changeover pressure?

Answer 54

40 bar (50 bar for deep dives)

Question 55

Partial pressure decimal rule?

Answer 55

Percentage ÷ 100

Question 56

ppO2 formula?

Answer 56

Absolute pressure × oxygen fraction

Question 57

ppO2 of 21% at 30 msw?

Answer 57

0.84 bar

Question 58

Total partial pressures must equal?

Answer 58

Absolute pressure

Question 59

ppm to partial pressure rule?

Answer 59

Divide ppm by 1

Question 60

ppm to percentage rule?

Answer 60

Divide ppm by 10

Question 61

Acceptable chamber CO2 limit?

Answer 61

Below 5 millibar

Question 62

Absolute temperature conversion (C)?

Answer 62

°C + 273 = Kelvin

Question 63

Absolute temperature conversion (F)?

Answer 63

°F + 460 = Rankine

Question 64

Charles’ Law meaning?

Answer 64

Pressure varies directly with temperature

Question 65

Hot fill then cold water effect?

Answer 65

Pressure drop

Question 66

Henry’s Law meaning?

Answer 66

Gas dissolved proportional to partial pressure

Question 67

Lower inert gas partial pressure causes?

Answer 67

Shorter decompression

Question 68

Equivalent air depth relates to?

Answer 68

Nitrogen narcosis and decompression

Question 69

Emergency bail-out sizing rule?

Answer 69

1 minute per 10 m of umbilical

Question 70

Bail-out at depth gives?

Answer 70

Minutes not hours

Question 71

Why cold water reduces bail-out time?

Answer 71

Lower cylinder pressure

Question 72

Who controls gas management?

Answer 72

Diving supervisor

Question 73

Who can abort a dive?

Answer 73

Diving supervisor

Question 74

What must be in writing?

Answer 74

Supervisor appointment

Question 75

What pressure is used for gas consumption?

Answer 75

Absolute pressure

Question 76

What pressure is used for quad volume?

Answer 76

Gauge pressure

Question 77

Main oral exam calculation trap?

Answer 77

Mixing gauge and absolute pressure

Question 78

Most common emergency mistake?

Answer 78

Using normal breathing rate

Question 79

Surface pressure in bar?

Answer 79

1 bar

Question 80

Surface pressure in ata?

Answer 80

1 atmosphere

Question 81

Why absolute depth is used?

Answer 81

Simplifies partial pressure calculations

Question 82

Absolute depth formula (msw)?

Answer 82

Depth + 10

Question 83

Absolute depth formula (fsw)?

Answer 83

Depth + 33