Advanced Nitrox Chapter 5-8 Flashcards
What is the formula for Boyle’s law?
P1 V1 = P2 V2
What is the formula for Dalton’s law?
Pg = Fg x P Pg = partial pressure of gas Fg = fraction of gas P = total pressure
What is a best mix calculation?
Made to plan for breathing gas needs for a specific dive
Fg = Pg/ P
How do you work out MOD?
Calculation to determine max depth to which a particular mixture can be dived
P = Pg/ Fg
How do you work out a partial pressure?
Calculation to determine partial pressure of a gas being breathed by a diver
Pg = Fg x P
How do you work out equivalent air depth?
(fN2) x (D + 10) / 0.79
-10
= EAD
What is the 40% oxygen rule?
Any regulator can be used with nitrox up to 40% mix
All cylinders used with nitrox must be o2 cleaned
What is compressor cleaning?
Compressors should not be used on mixes over 21% without being prepared
What is cylinder cleaning?
Titanium and aluminium cylinders should not be used for nitrox
Cylinder must be cleaned of all hydrocarbons
How can you minimise risk to equipment?
Turn valves on slowly
Maintain level of cleaning present
Never put cleaned equipment back in use after use with non-compatible gases
What air should be put in a cleaned cylinder?
Only filled with oxygen compatible air (hyper pure or modified grade E air)
Goes through filtration to remove hydrocarbons
How should oxygen cleaned cylinders be used with air?
Must be cleaned prior to use with mixes over 40%
What are computer generated dive tables?
Allow detailed dive planning
Do not allow any flexibility or modification
Need to integrate conservative procedures
Describe personal dive computers
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
Describe programmable dive computers
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
What do you need to include in your dive plan?
Gas requirements
Oxygen limits and calculations
Nitrogen limits and strategy for tracking dive
Thermal considerations
What is respiratory minute volume (RMV)?
Amount of gas a diver moves in and out of their lungs in 1 minute
What will RMV depend on?
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
How can you calculate RMV?
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
What is the cylinder baseline?
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
Why is RMV important?
Allows for more complete dive planning
Critical for CCR divers in order to calculate bailouts
What is oxygen planning?
Calculate and plan CNS exposure and OTUs
Numbers should be within acceptable limits
What are nitrogen limitations?
Dive tables can be used to plan for nitrogen exposure
What are thermal considerations?
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
