Next Meeting: Tuesday, October 21, 2014
Andrews University, Biology Amphitheater, Price Hall, Berrien Springs, MI
Meeting starts: 7:30 p.m. (Every 3rd Tuesday of every month except December)
Greet attending members, Introduce visitors, Present specific Club Related information,
Discuss general dive related news, Present any Show & Tell, Open the floor for discussion of current diving experiences and lessons learned if any, Pizza at Roma’s after meeting closure. Free copies of “Diver Training” magazine will be available at this meeting.
Last Meeting Highlights:
There were 13 members and 1 visitor (John Nedoba) in attendance, highlights of the early September Mackinaw & Cheboygan wreck and grubbing dive week were discussed, mentioned two items provided to the Cheboygan Museum, identified & discussed dives made in Gull Lake, Saint Joseph river, and Lake Michigan, Kevin A. provided a nice run down on multiple shallow water wrecks on the West side of Michigan, Mary B brought up for discussion the possibility of a Pumpkin dive (Oct), reminder of the clubs annual Turkey Dive (Nov 29), mentioned Wolf’s Marine Scuba & Boating miscellaneous sale, Jim S spoke about the current status of Wreck Buoy permits (re: SWMUP), Sir Larry spoke about cleaning your B.C., and under Lessons Learned per Richard C “If you have ear issues make sure you go to an ear specialist.”
Safety Tip of the Month:
OXTOX: If You Dive Nitrox You Should Know About OXTOX
DAN discusses the dangers of oxygen toxicity when using nitrox as a breathing gas.
(this is an excerpt from the entire article, it is strongly suggested you read the entire article at http://www.diversalertnetwork.org/medical/articles/OXTOX…..)
One thing you should be impressed with by now is that oxygen toxicity is fickle; convulsions have occurred at shallow depths under conditions where most experts would not have expected them to occur. So, as an air sport diver, how should you view nitrox diving? The answer is: carefully.
Experts rationalizing why particular oxygen exposure limits do or do not cause oxygen toxicity are like investment analysts rationalizing movements in the stock market – everyone has a reason, but no one really knows why!
First, whenever a gas is breathed with an oxygen fraction above 21 percent, you should assume that oxygen toxicity is a possibility and have appropriate training. This not only means having a buddy clearly visible at all times but also knowing what action to take should oxygen toxicity occur.
Second, using equipment designed to compress high oxygen mixtures can be hazardous in itself and requires special training.
Third, what you get in your tank may not be what you expect. A method of analyzing the amount of oxygen in the tank independent of the filling station must be available.
Fourth, if you are attracted to rebreather’s, remember that they are complex pieces of life-support gear, requiring much more care and feeding than the good old scuba regulator. If you get into rebreather’s, expect to get hit with good-sized training and maintenance costs.
Finally, there is the matter of keeping the possibility of oxygen toxicity to a minimum.
Moving Ahead: For open-circuit scuba diving, consider the “green light“ region any oxygen partial pressure of 1.4 ata or less (this is about 82 feet / 25 meters on a 40-percent oxygen mix.) As long as this level is never exceeded, other limitations of open-circuit scuba diving will limit the exposure time to lengths where CNS oxygen toxicity is unlikely to be encountered, even for exposures approaching four hours.
Proceeding with Caution: Between 1.4 ata and 1.6 ata (this is 99 feet / 30 meters on a 40-percent mix) is the “yellow light” region. The possibility of oxygen toxicity at 1.6 ata is low, but the margin of error is very slim compared to 1.4 ata. Individual variation, the likelihood of an unplanned depth excursion causing an increase in oxygen partial pressure, and the possibility of having to perform heavy exercise in an emergency put the possibility of oxygen toxicity at levels where caution should be exercised. Thus, levels of 1.5 to 1.6 ata should be reserved for conditions where the diver is completely at rest, such as during decompression. Again, as noted previously, the dive team must still be prepared for the possibility of an oxygen convulsion at these levels.
Stop! Above 1.6 ata is the “red light” area. Just don’t do it. Yes, there is evidence that short exposures at higher levels of pO2 (oxygen partial pressure) are possible but so are convulsions. At these levels, oxygen exposure depth/time limits must be adhered to. Even mild exercise may put divers breathing high-density nitrox mixes at increased risk; and even open-circuit scuba divers can achieve durations likely to get them into trouble at these levels. Diving using these high partial pressures of oxygen should be left to the trained professionals who can weigh the risks and benefits and who have the necessary training and support structure in place, if an oxygen convulsion occurs. Check out the entire article at:
“Always Dive Safe and Dive Smart”
Don’t dive if you feel pressured. Remember, if you’re not having fun, stop diving.