Advanced Nitrox Chapter 5-8

Question 1

What is the formula for Boyle’s law?

Answer 1

P1 V1 = P2 V2

Question 2

What is the formula for Dalton’s law?

Answer 2

Pg = Fg x P
Pg = partial pressure of gas
Fg = fraction of gas 
P = total pressure

Question 3

What is a best mix calculation?

Answer 3

Made to plan for breathing gas needs for a specific dive

Fg = Pg/ P

Question 4

How do you work out MOD?

Answer 4

Calculation to determine max depth to which a particular mixture can be dived
P = Pg/ Fg

Question 5

How do you work out a partial pressure?

Answer 5

Calculation to determine partial pressure of a gas being breathed by a diver
Pg = Fg x P

Question 6

How do you work out equivalent air depth?

Answer 6

(fN2) x (D + 10) / 0.79
-10
= EAD

Question 7

What is the 40% oxygen rule?

Answer 7

Any regulator can be used with nitrox up to 40% mix

All cylinders used with nitrox must be o2 cleaned

Question 8

What is compressor cleaning?

Answer 8

Compressors should not be used on mixes over 21% without being prepared

Question 9

What is cylinder cleaning?

Answer 9

Titanium and aluminium cylinders should not be used for nitrox
Cylinder must be cleaned of all hydrocarbons

Question 10

How can you minimise risk to equipment?

Answer 10

Turn valves on slowly
Maintain level of cleaning present
Never put cleaned equipment back in use after use with non-compatible gases

Question 11

What air should be put in a cleaned cylinder?

Answer 11

Only filled with oxygen compatible air (hyper pure or modified grade E air)
Goes through filtration to remove hydrocarbons

Question 12

How should oxygen cleaned cylinders be used with air?

Answer 12

Must be cleaned prior to use with mixes over 40%

Question 13

What are computer generated dive tables?

Answer 13

Allow detailed dive planning
Do not allow any flexibility or modification
Need to integrate conservative procedures

Question 14

Describe personal dive computers

Answer 14

Allow for multiple gas mixes and greater flexibility
Can modify in real time during dive
Must make sure an modification to existing dive plan is done so by taking into account all of the other parameters

Question 15

Describe programmable dive computers

Answer 15

Some interface with personal computer and some use controls on dive computer
Most allow you to increase level of conservatism
No room for pushing limits as they calculate in real time

Question 16

What do you need to include in your dive plan?

Answer 16

Gas requirements
Oxygen limits and calculations
Nitrogen limits and strategy for tracking dive
Thermal considerations

Question 17

What is respiratory minute volume (RMV)?

Answer 17

Amount of gas a diver moves in and out of their lungs in 1 minute

Question 18

What will RMV depend on?

Answer 18

Change depending on equipment used, temperature of water and amount of diving done by the diver, whether it is working portion of dive or decompression

Question 19

How can you calculate RMV?

Answer 19

Diver swims at constant depth for set period of time

Looking at pressure of gas breathed over a period of time, corrected for depth and converted to volume used at surface

Question 20

What is the cylinder baseline?

Answer 20

Way to figure out constant for each cylinder
Calculated as volume per unit of pressure
Wet volume x fill pressure = volume of gas in cylinder

Question 21

Why is RMV important?

Answer 21

Allows for more complete dive planning

Critical for CCR divers in order to calculate bailouts

Question 22

What is oxygen planning?

Answer 22

Calculate and plan CNS exposure and OTUs

Numbers should be within acceptable limits

Question 23

What are nitrogen limitations?

Answer 23

Dive tables can be used to plan for nitrogen exposure

Question 24

What are thermal considerations?

Answer 24

In technical diving, running out of heat is as critical as running out of gas
Plan based on water temp, number of dives in the day, thermal protection, weather, depth, personal thermal characteristics and mission needs