Oxygen_Deficient Atm. Confined Space Safety

October 29, 2002

Following the tragic death of our friend Arnie Tanzman, and since it is necessary for most of us to spend hours and hours in the tail cone of our Seawinds, it is appropriate to make some information available about this little known deathly hazard.

To the surprise of most people hearing about it for the first time, death in an oxygen-deficient atmosphere is almost instantaneous. It occurs after just one or two breaths!

Oxygen-deficient atmospheres occur from many causes, but most often because the air in an enclosed space is displaced by another gas. This can occur with even non-toxic, inert gasses. Often times, the space doesn't even have to be very enclosed. In some cases, where there are heavy gases present (like argon and some other welding gases) they can deplete the oxygen at the floor level of a large room.

The top of some spaces can have oxygen-deficient atmospheres from lighter than air gasses as well.

During the mid 70's, while working in the Nuclear industry, we had extensive safety programs concerning this sinister hazard. One of the incidents that was used as an example is the following:

(Please note, this story is being related from memory, some details will be missing) During the 70s, many of the dairy farmers and cattlemen were installing large ground level tanks in which they would liquefy manure so that it could be easily pumped and handled for fertilizer. At one such installation, during the start-up process of the new facility, a farmer entered the tank and did not come out. His hired man, becoming concerned, went in to see if something was wrong. When the men had been missing for a time, one of their wives called the sheriff, who went out to investigate, and also entered the tank. Finally, one of the observers figured out that the tank was probably filled with methane gas. All three of the men were found inside the tank, dead.

Many people mistakenly think that a respirator or mask will protect them. Not so, if there is no oxygen, only an oxygen supplied device can help.

While in the tail cone of your Seawind, always ensure that you have adequate ventilation. During the building process, while the tail cone is open, most of us place an air supply fan either in the front, blowing back through the tail cone, or a small fan in the water rudder area, pulling air through. After the tail is enclosed, as in Arnie's case, just a fan may not be sufficient since there is no exit for the air.

There is an abundant amount of information about this topic on the web. One of the most brief, but thorough treatments is provided on the Air Products Company web-site at the link below. Click on the scrolling text, then select "Safetygram - 17: Dangers of Oxygen Deficient Atmospheres" and read it over. (Please note, you will need adobe acrobat reader. It is provided at the link if you don't have it.)

What ever you do, keep safety at the top of your list.

Safety regards,

Brent Carlson