Flashcards in RDP Deck (28):
What is halftime?
Time in minutes for a compartment to go halfway from its beginning tissue pressure to full
Fast vs slow tissues
Fast - absorb and release nitrogen quickly. Shorter halftime
What is the m value?
Maximum tissue pressure allowed to be left in a compartment after a dive
The faster the compartment, the shorter the half life, the higher the M value (more nitrogen allowed on surfacing)
M value is max value of inert gas pressure that a hypothetical tissue compartment can tolerate before showing symptoms of DCS
Also called: limits for tolerated over pressure, critical tensions and supersaturation limits
What are pressure groups on the RDP?
Representation of the amount of nitrogen absorbed
How are NDLs determined?
By the tissue compartment that reaches its m value first
On deep dives you have short NDLs as fast tissues reach m value first
On shallower dives you have longer NDLs as slow tissues reach m value first
What is the controlling department?
The compartment that reaches the m value first
What is the difference between the RDP and US Navy tables?
RDP: no deco stop, 14 compartments, 60 minute surface credit halftimes, faster gas washout, 6 hours to be clear of nitrogen after a dive. Designed for multiple dives a day with shorter surface intervals, gives longer bottom times on multiple dives - for recreational divers
US Navy tables: stage decompression, 6 compartments, 120 minute surface credit halftimes, slower gas washout, 12 hours to be clear of nitrogen. Designed for less dives a day with longer surface intervals (military)
How was the RDP developed?
Developed in 1987 and tested in 1988 by Dr Raymond Rogers working with DSAT (Diving Science And Technology)
Why was the USN tables originally the standard?
Making tables was difficult without computers
Many sports divers began as military divers
USN tables were widely available
Spencer limits, EE washout
Approx same M values as RDP so similar NDLs
During SI, all compartments release nitrogen at surface at their underwater halftime rate
EE = exponential exponential
Means repetitive deep dives require shorter SI than RDP but repetitive shallow dives require longer SI than RDP
Can permit dives that are not tested to work
Spencer limits, 60 minute washout
Similar NDLs to RDP
At surface, all compartments 60 mins or faster washout at 60 min rate (like RDP), all slower compartments washout at their underwater halftime rate
Dives similar to what RDP allows
Buhlmann limits, EE washout
Further reduced M values so more conservative NDLs
All compartments washout at underwater halftime rate
Uwatec and Scubapro computers
General rules for using the RDP
Pressure groups can not be swapped with other tables
Plan dives in cold water 4m deeper than actual
Plan deepest dive first
Limit max depths to experience level
When planning 3 or more dives a day, if the end pressure group after any dive is W or X, min SI is 1 hour. If it ends on Y or Z, min SI is 3 hours
Limit following dives to 30m or less
Safety stop at 5m for 3 mins on all dives
Always make a safety stop: after any dive below 30m, any time you will surface within 3 pressure groups of NDL, when a dive is made to any limit (black box) on the RDP
What are the depth limits for each diver grade?
Open water 18m
Deep specialty 40m
Emergency deco procedures
8 mins at 5m must be done if NDL is exceeded by 5 mins or less, and diver must stay out of the water for 6 hours
If NDL is exceeded by more than 5 mins, then do 15 mins at 5m minimum, and diver must stay out of the water for 24 hours
Dives deeper than 40m
Ascend to 5m (at 18m a minute) and do a 8 min deco stop, and diver must be out of water for 6 hours
Missed deco stop
Remain out of water, breathe O2 and do not go back in for 24 hours
Diving at altitude
Over 300m above sea level requires training
Add 4% to depth for every 300m above sea level
Flying after diving
Minimum of 12 hours
For multiple dives a day, deeper dives or dives going into deco, 18 hours is recommended
What is Pyle's method for calculating deep stops?
Calculate a decompression profile using normal software
Take distance from bottom of dive to first deco stop and find mid point
This is deep stop - spend 2-3 mins here
Recalculate decompression profile including deep stop
If distance between deep stop and first deco stop is more than 30ft, add a second deep stop between the first deep stop and the first deco stop
Repeat until there is less than 30ft between deep stops and first deco stop
Workman M values
Established linear relationship between depth pressure and the tolerated inert gas pressure in each tissue compartment
Buhlmann M value
Same as Workmanship but based on absolute pressure not depth pressure
Both hands joined above head on surface means?
What do you need to use theoretical depth tables?
Altitude of the dive
What is a visual inspection?
Checking inside tank and lubricating and checking o rings
What type of depth gauge is useful at altitude?
Coral has a symbiotic relationship with which organism?