Chapter 7 - Decompression Tables And Computers Flashcards
What are the decompression tables dependent on?
The theoretical tissue compartments
What are some of the different decompression tables?
British RNPL table
United States Navy
Canadian diving tables
What did Haldane do?
Examined the times for nitrogen in the various tissue compartments to half. He called this the half life
What does the buhlmann tables show compared to US navy tables?
Shows saturated tissues in a different colour which returns to normal colour when the off gassing has reduced the nitrogen load sufficiently
What does dive time mean?
Times from leaving the surface to returning to 6m or the first stop on the final ascent
What does ascent check depth mean?
A pause is made to check that the dive has been conducted according to plan - usually 6m
What does depth mean?
The deepest point of the dive - metres
What does descent rate mean?
Maximum - 30 mins per meter
What does ascent rate mean?
Maximum 15 meters per minute to check depth
What does surfacing code mean?
The code just after surfacing from a dive
What does current tissue code mean?
Before a second dive, the surface interval is applied to the last dives code to produce the current tissue code
What does surface interval mean?
Time from arriving on surface after dive 1 to leaving surface on repetitive dive
What does no stop dive mean?
Doesn’t require decompression stops
What is a decompression dive?
One that requires a decompression stop
What is a decompression stop?
Time spent at a specific depth for a specific duration during the ascent which allows the diver to unload excess nitrogen
What are level 1 decompression tables used for?
> 984 mb atmospheric pressures at sea level
What are level 2-4 tables used for?
Diving at altitude or reduced atmospheric pressure
What is the repetitive dive depth?
A dive made within 6 hours of another dive - the deepest point of the dive in metres
What is a pressure group?
A method of defining the amount of nitrogen in the divers system throughout a series of repetitive dives
What does RNT mean?
The residual nitrogen time
How do you calculate the total bottom time (TBT) when diving with PADI?
Residual nitrogen time + actual bottom time
When must a safety stop be completed with PADI?
If the dive was to 30m or deeper
The pressure group st the end of the dive is within 3 pressure groups of the no decompression limit
The dive is up to the limit of the recreational dive planner
What is a decompression schedule?
Description of the dive given as max depth/ bottom time
18 m / 20 mins
What are the considerations that must be made for different conditions that may occur during diving operations?
Repetitive dives with deco stops Short surface interval periods Multi level diving Diving at altitude Incorrect ascent procedures followed
What should you add to the depths when diving at altitudes of
100-300m
300-2000m
2000-3000m?
- 25
- 3
- 5
