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Within the rules and purpose of this forum --" the promotion of safe diving through accident analysis.
Accurate analysis of accidents and incidents that could easily have become accidents is essential to building lessons learned from which improved safety can flow."
Please...Remind yourself of the rules before you add to the thread...
(1) Events will be "scrubbed" of names. You may refer to articles or news releases already in the public domain, but the only name you may use in this forum is your own.
(2) No "blamestorming." Accident analysis does not "find fault" - it finds hazards - and how to reduce or eliminate them.
(3) No flaming, name calling or otherwise attacking other posters. ....etc.
Other threads that have attempted to discuss this accident have been locked/edited/or deleted because of posters not following the rules. It is my hope that this thread will remain constructive, instructional and maybe even save a life by discussing the danger of Carbon Monoxide (CO) and what can be done to prevent and detect it.
Backround from Scuba-Doc:
"Carbon Monoxide poisoning is a rare cause of problems when diving, it does occur when there is contaminated air in recreational diving tanks. CO poisoning is the leading cause of poisoning deaths in the U.S.(about 8600 deaths per year) and is easily missed unless health care providers are especially vigilant.
The most commonly observed result related to CO poisoning is neurological dysfunction; abnormalities in the cardiac, pulmonary and renal organ systems do occur. About 14% of patients sustain permanent brain damage, and delayed neurological sequelae do occur 3-21 days later in about 12% of people.
Pre-existing cardiovascular disease
Age greater than 60 years
An interval of unconsciousness (longer the higher the risk)
Little association with COHgb (carboxy hemoglobin)
Carbon Monoxide signs:
Tachycardia (rapid pulse)
Tachypnea (rapid breathing)
Retinal venous engorgement (as seen through an ophthalmoscope)
Ekg conduction defects
COHgb greater than 20%
Carbon monoxide in diving is the product of incomplete combustion of hydrocarbons and is usually from compressors and cigarette smoking. In addition to the effect on the hemoglobin molecule, it has a toxic effect on the cytochrome A3 system. Prevention requires periodic air sampling. The maximal allowable level is 20 ppm (0.002%)"
In light of recent Roatan reports of 2 diver deaths on the same dive from "bad air" who were diving with a top dive resorts operation, I have been searching for answers to a few questions and would like to take every reasonable step to protect myself from a similar mistake.
---Are the symptoms of CO poisoning detectable by a diver in time to surface/abort the dive?
---If so what's the time frame for detection?
---What is the lethal ppm range?
---Do fill stations (resort or otherwise) routinely check for CO and measure ppm?
---If so how often?
---What is the best method for a diver to self test his tanks for CO?
---Does anyone manufacture a combination Nitrox/CO analyzer/detector?
Now, without flaming or naming....let's all learn something from one another and discuss CO poisoning. Thanks in advance for your thoughtful replys.
Last edited by DVRCARRIB; August 2nd, 2005 at 07:18 PM.
Hold the white cap over the inlet of detector for 1.5 to 2 minutes to displace ambient air and fill chamber with tank air. If CO is > 10 ppm the display will light automatically and beep. If CO < 10 ppm it will show amount down to 1 ppm only if test button is pushed.
I have used one for two years and had it recalibrated once. It was off by about 2 ppm which is a very stable sensor. Just don't leave sensor in hot car otherwise it can be used to analyze air, nitrox, or hypoxic trimix.
Most common reason for detector to alarm on dive boat has been excessive CO from rear exhaust on inboard gas engine charter boats. The levels of CO can get quite high as the exhaust due to the 'station wagon effect' is sucked back into aft cabin of boat even while underway.I have seen one fellow vomiting and headache from this CO source on boat.
The home detectors are not set to display until 35 ppm is reached to prevent excessive calls to emergency services and gas companies. This level is too high for breathing CO at high partial pressures.
Thanks for the replies thus far. A low ppm range handheld ready-to-go-right-out-of-the box CO dectector for tank testing seems to be an elusive item, McGuyver rigging one together is the only option I've found thus far.I don't mind a build it yourself solution but I wish I could find a ready made system tailored to divers.---Do fill stations (resort or otherwise) routinely check for CO and measure ppm?
---If so how often?
As far as facts, within the rules of this Forum here are the facts that prompted my post and why I am going to purchase my own CO detector.
There is some speculation that a batch of tanks were CO contaminated (allegedly) recently at a resort during a fill by a faulty compressor. The contamination problem was detected. The tanks were placed aside, emptied, and then refilled with clean air. The diveboat was loaded with the new tanks. A resort diver decided to join the diveboat at the last minute for a scheduled two tank dive. Two additional tanks were loaded on the boat from the dock. The divemaster grabbed one of the newly loaded tanks for himself and the other was used by the late arriving diver. Unfortunately, both of the newly loaded tanks were from the "bad air" batch---they had never been emptied. Divers entered the water 1st for a planned 80ft max depth type dive, followed by the divemaster. Within minutes the divemaster surfaced was helped aboard and experienced a cardiac arrest. Due to the irreversible binding nature of CO to Hemoglobin, he was unable to be resuscitated. The dive group was summoned back aboard and found to be minus one diver. A quick search was mounted and they found the late arriving diver dead in the water. All the resorts boats were called back and diving was suspended for the subsequent day intil the remaining tanks were checked and double checked. (All circumstances are under investigation.)
I've always done a "sniff test" of my air for hydrocarbons. I just don't feel that that is adequate anymore----I want to be the one who checks and double checks my air. The resort where this occured is a top notch operation with a sterling reputation and if it can happen there----it can happen anywhere.
Last edited by BigJetDriver; August 3rd, 2005 at 12:07 PM.
Reason: Removal of reference to specific case--R. Davie
Its as factual as your statement. Please share if you have any specifics that would further the discussion.
I apologize if my statement came off as "babysitting". The part of the original post that I was referring to was the "statement of fact" about a certain specific accident. I wasn't aware that any official reason had been given. I would really like to see sources provided when facts are put on the table, otherwise it's no more than speculation.
With that being said, the discussion on CO poisoning is very worthwhile. I know our compressor and cascade system is constantly monitored and will alarm if CO levels are registering above acceptable limits.
Last edited by BigJetDriver; August 3rd, 2005 at 11:45 AM.
Reason: Removal of reference to specific case--R. Davie
Thanks lord1234....the "CO Cop - Carbon Monoxide Tester" from scubatoys is certianly affordable and looks easy to use. Does anyone know what the senseitivity of the color change reaction is? In otherwords, what level of ppm is required for a color change/positive test to occur?