ADP Chapter 1 + 2 Flashcards
What does the schedule of a dive depend on?
Descent rate Depth Ascent rate Breathing mix Bottom time
Why must we adhere to decompression stops?
Stops are necessary for nitrogen gas to be partially eliminated so that excessive nitrogen pressure is eliminated before surfacing
What is a virtual overhead?
When a decompression stop must be made - prevents the diver from coming straight to the surface
What makes up the other gases in air, apart from nitrogen and oxygen?
Argon
Water vapour
CO2
Neon, krypton and xenon (rare)
What are the measurements of pressure at sea level?
14.7 psi
1.0132 bar
760 mmHg
29.92 inHg
760 torr
What is gauge pressure?
Effect of atmospheric pressure has been zeroed out
Reads 0 at 1 bar
What is absolute pressure?
Pressure that includes the atmosphere above (1 bar at sea level)
Describe nitrogen gas
Colourless, odourless and tasteless
100ml of water can dissolve 2.4ml of nitrogen at standard temperature and pressure
What are the effects of nitrogen on body?
Excess freely dissolved nitrogen enters fatty substances of membranes of neurones, interferes with conduction, reducing excitability = narcosis
Dissolving and diffusing nitrogen into tissues of body - if released in free form it can cause pain and nerve system disruption
When do you find anoxia in diving?
Steel cylinder with rusted inside uses up O2
CCR units that are not properly maintained
What is the range of long term low dose oxygen exposure?
0.6 bar and 1.0 bar
Loraine Smith effect (pulmonary o2 toxicity)
When does the oxygen clock start?
Pressures over 1.0 bar
What is the Paul Bert effect?
CNS oxygen toxicity
What depths do you reach CNS toxicity with?
Air = 66.5m EAN32 = 40m EAN40 = 30m EAN50 = 22m EAN80 = 9m 100% O2 = 6m
When is a 2 hour surface interval required?
If diver exceeds 80% of single dive exposure
