Compressor and smoke distance

[Griffo]

I appreciate you bringing this to my attention. ... I honestly thought the scuba specific version was more money because of cost to build for a small market size.

Because we are breathing compressed air at depth, the effect of any CO is magnified. Ergo, the scuba sensors have to be able to accurately read far lower CO concentrations than normal domestic meters.

 

[Justin Bove]

I don't think so. I think it's giving a false feeling of safety. When dealing in double digits of parts per million of a gas that has no taste or smell and can be produced internally by overheated compressors, accuracy really counts but can be severely challenged.


You can ask, but it's not likely that they stock calibration CO. Besides, how many tests with how many variables would you need? If you want to do research, find out which sensor is used, then find official specs on that model, including rate of drift since that unit can't be calibrated I don't think. Then you'd have to also study how the unit actually displays in ranges with whatever the sensor reads.


If one is inaccurate, it can go either way. The cheapest solution I have found with a reliable unit is the Sensorcon CO Inspector. I leave mine on all the time and carry it everywhere so it does multiple duties as a home & hotel room alarm, vehicle alarm, restaurant alarm, etc. - even on planes as they don't have alarms. For scuba, use a gallon ziplock. You can get some higher readings than accurate with the ambient air getting sucked in, but we're still working with "close enough." For example, Cozumel marina air will easily register double digits with all the boat motors, but a careful bag test done there should read below 10ppm, or do the test at sea - except I hate to wait. It's tough as advertised in their youtube videos, too. I ran mine thru the clothes washer with bleach attached to my khakis - no problem. Oh, the battery will last 2 years if on all of the time, and by then it's time to send it in for sensor & battery service.

Now sensor drift will happen. I am not going to mail mine in every six months for calibration service, so I allow for that. I do not remember how much drift is possible so I'll call their office again before the next trip. They've gone up a bit since I got mine, $159 now, but this guy is offering a new one for $115, free shipping. Sensorcon Portable Carbon Monoxide CO Detector/Meter/Monitor-Test Gas Appliances | eBay

That’s a great price. Way cheaper then this Palm CO Carbon Monoxide Analyzer

 

[Ayisha]

I'm sure Vitas is still patiently waiting to have a few conversations, hey Dandy

So just briefly


Coroner's investigative report

IDENTITY

First name at birth Tasha Anne
Birth name Johnson-Wallace
Birth date 1950-09-07
Sex Female

IDENTIFICATION OF THE DECEASED PERSON

Ms. Johnson-Wallace was visually identified at the scene of her death.

CIRCUMSTANCES OF DEATH

On September 10, 2017, early in the afternoon, Ms. Johnson-Wallace participates with others people with advanced scuba diving training at Sacacomi Lake. Following a descent of about 60 feet, performed without problem, the lift is done according to the taught techniques. At about 15 feet from the surface, the instructor asks Ms. Johnson-Wallace to perform a mask drain, but she refuses or, at least, does sign of his inability to proceed. The instructor or the person named, in the middle, the "Dive master", supports her and shows her how to do it. Everything is successful at this moment and the next step is to go back at the decompression stops.

All of a sudden, the instructor realizes that Mrs. Johnson-Wallace is breathing quickly. he then takes a physical contact, that is to say by grasping it by a strap and in the looking in the eyes to reassure her. This lasts about 15 seconds. He leaves eyes his binomial (term designated for diving partner or "body") for 5 seconds to check what the other two students who are part of the training dive are doing. he always keep a physical contact with her. Turning to see her again, he finds that it does not have its regulator in the mouth. Between these two sequences, it flows about 30 seconds no more. The instructor tries, in vain, to replace her regulator.

In view of this lack of success, he carried out an emergency recovery during which, Mrs Johnson-Wallace does not move in any way, has wide eyes, does not seem to have breathing.

Arrived at the surface, follow a series of maneuvers of resuscitation, in less than one minute from the moment the instructor becomes aware of a difficulty. He shouts "help" and requests that 911 be dialed; he starts the artificial respiration technique commonly called "mouth-to-mouth" after taking off his mask. She does not do not breathe.
He pulls her to the shore and the maneuvers continue while student in the group rushes to remove her wet suit
for clear the abdomen. Another student arrives immediately and begins the chest compressions.

Less than a minute later, the group leader brings a defibrillator and the device
to oxygen. The instructor administers oxygen in continuous flow and compressions
thoracic are still in progress. Seconds later, the instructor responsible
activates the defibrillator (DEA), but other cardiopulmonary resuscitation techniques are
continue until paramedics arrive at 1339. The DEA does not recommend any shock.

Transportation to the nearest hospital is rapid, around 13:41, during which time
paramedics are busy trying to resuscitate, until the arrival at 14 h 06.

The medical staff in place immediately takes Ms. Johnson-Wallace in charge and
applies all possible resuscitation techniques until 2:18 pm, the hour of the report of deceased.


EXTERNAL EXAMINATION, AUTOPSY AND TOXICOLOGICAL ANALYSIS

An autopsy was performed on September 12, 2017 at the Laboratory of Forensic Sciences and
forensic medicine in Montreal. In his report, the pathologist described, in his review of
lungs, a distinctly distended aspect of some cells that could be secondary to
rupture of alveolar walls during the ascent (distended and congested lungs, 940
grams each). He took into account the subcutaneous emphysema that would have been perceived at the neck
during resuscitation manoeuvres. In his comments, one can read that a drowning
remains plausible, but could have occurred after the victim lost her
regulator. This, he says, would not explain the origin of the incident and it would be more
of a consequence than of a cause. He also finds no traumatic lesions
significant and no evidence of intervention by a third party. No other contributory injury to
death was observed.

Toxicological analyzes were performed at the Laboratory of Forensic Sciences and
forensic medicine in Montreal. The alcohol level was negative.
No other substance has been detected.


ANALYSIS

Ms. Johnson-Wallace was 67 years old. She was spending the weekend in a camp
development for divers. Her big wish was to get her diver card
advanced. Since his arrival until the day of the accident, all her colleagues
and instructors) described her as a dynamic person and that nothing left
believe she may not be fit to play this sport.

The day before, Saturday, September 9, 2017, she had made three deep-water dives and
the next day, a descent of nearly 75 feet.

The investigation was conducted by the Sûreté du Québec (MRC of Maskinongé) which, in its
report, notes that a problem occurred during the mask emptying exercise, that is, a
very common technique learned in scuba diving. Ms. Johnson-Wallace does not
run at the first instruction and we do not know why. Except that a recovery took place successfully.

The police were called around 1:00 pm, and took care of protecting the scene until
the arrival of an on-site investigator followed by a technician from the Forensic Identification Service (SIJ).

The people involved in this activity were met and reported that
Mrs. Johnson-Wallace's accompanying instructor spared no effort to
try to save her life. For example, they mentioned that the latter had made
breaths, chest compressions, and ensuring that the AED is brought as quickly as possible
possible.

The diving equipment belonging to the victim was kept in plain sight on the bank
Sacacomi Lake to be transported, under my prescription, for expert appraisals.

In addition, I consulted the dive incident report written by the instructor called the
"Dive master", in addition to the two statements made to the designated investigator. Following
comments made by the expert who examined all the equipment he claimed he did not see
Ms. Johnson-Wallace trying to put her emergency pressure regulator on
"Octopus" and that suddenly she became inert.

The equipment expertise also noted that Ms. Johnson-Wallace was able to
carry an additional 13 pounds of lead. But the investigation also showed that she had passed
a buoyancy test and it was determined that additional 13 pound lead shots
were required. We remember that she had done 3 other dives before with this
configuration of sinkers, no problem.

On the other hand, it appears from the observations
expertise that the regulator used by Ms. Johnson-Wallace was
not recommended under water at temperatures below 10 degrees Celsius (icing
is possible). However, according to the dive profile and the "dive master" declaration, the water
could reach only 5 or 6 degrees Celsius at a depth of 60 feet.

Thus, the possibility of icing of the regulator has been examined during the present
investigation, because it is true that in the latter situation, the vast majority of the time, the Air flow remains open and becomes continuous at the expander. However, he arrives sometimes, but rarely, that there is obstruction of the regulator, especially in icy water (eg example, diving in the Arctic). Asked again at my request, the "dive master" has
mentioned that there was no continuous airflow from Ms.'s regulator
Johnson-Wallace, which minimizes the probability of occurrence of this hypothesis.

Moreover, by consulting experienced divers, I learned that a diver fully
conscious and alert who is facing an emergency with his main regulator will use
immediately his "Octopus" (2nd regulator), then try to solve the problem in a
second time.
In the case of Ms. Johnson-Wallace, I see that in very short
time, she became inanimate, had her eyes wide open and empty, while her
regulator was out of his mouth, floating in front of her. This table suggests discomfort
relatively sudden, in the context of a brief episode of faster breathing.

In short, the investigation suggests that Ms. Johnson-Wallace suffered a barotrauma
pulmonary, with a possible resultant drowning.


CONCLUSION

Ms. Tasha Anne Johnson-Wallace is probably dead from drowning, but he is not

It is not possible at autopsy to determine the trigger.

This is an accidental death.

I, the undersigned, coroner, acknowledge that the date indicated, and the places, the causes, the circumstances described above were made to the best of my knowledge, as a result of my investigation, in faith of which I signed, in Saint-Lucien, this 17 July 2018.


Yvon Garneau, coroner...

Do we know which reg the victim was using? Is it possible that it was an upstream reg that failed closed instead of open, like more common downstream regs?

 

[chillyinCanada]

Seems unlikely to have been the air in her tank, though I still believe it should be a standard check in such situations.

 

[chillyinCanada]

Something happened to her on her ascent from 60' to 15'. Despite that she was obviously already feeling the effects of whatever the problem was, she did manage to do the mask clear upon second instruction.

Does anyone know if Tasha was a smoker?

 

[happy-diver]

Do we know which reg the victim was using? Is it possible that it was an upstream reg that failed closed instead of open, like more common downstream regs?

I don't know, but using upstream valves theses days, I pretty sure not

and then there's this from the coroners report

"All of a sudden, the instructor realizes that Mrs. Johnson-Wallace is breathing quickly. he
then takes a physical contact, that is to say by grasping it by a strap and in the
looking in the eyes to reassure her. This lasts about 15 seconds. He leaves
eyes his binomial (term designated for diving partner or "body") for 5 seconds
to check what the other two students who are part of the training dive are doing. he
always keep a physical contact with her. Turning to see her again, he
finds that it does not have its regulator in the mouth.

Between these two sequences, it flows about 30 seconds no more.

The instructor tries, in vain, to replace his HER regulator.

In view of this lack of success, he carried out an emergency recovery"

So with regards to "flows" my guess is this is elapsed time from discovery to commenced recovery
and my assumption is that the instructor would not attempt reg replacement without purged air flow

also I've taken artistic licence with the original translation in swapping he for she, except for above
where in translation, gender accuracy is the first norm to fall to pieces, a bit like the Western World

 

[happy-diver]

Seems unlikely to have been the air in her tank, though I still believe it should be a standard check in such situations.

some pertinent highlights of coroners analysis prior to his finding.

"The police were called around 1:00 pm, and took care of protecting the scene until
the arrival of an on-site investigator followed by a technician from the Forensic Identification Service (SIJ).

The diving equipment belonging to the victim was kept in plain sight on the bank
Sacacomi Lake to be transported, under my prescription, for expert appraisals.

Toxicological analyzes were performed at the Laboratory of Forensic Sciences and
forensic medicine in Montreal. The alcohol level was negative. No other substance has been detected."



Whilst air quality is not mentioned, the victims tox screen is summarised above
and an appropriate chain of custody regarding equipment is implied


So NOTOX and while we have aspiring tech divers listening
is one of those things that's supposed to remind you of stuff

namely when swapping from one breathing gas to another

N ote the name on the stage bottle you are carrying and the MOD
O bserve your actual depth
T urn on your valve and check the pressure
O rient the second stage, so make sure it belongs to the bottle you are about to breathe from
X amine all the others in your group for all the same stuff as above

so there