100% O2 @ 50 Fsw

[HarryH97]

JBD, No kidding around...What are you telling us? Are you thinking of hurting yourself or someone you know??

 

[BigJetDriver]

Any thoughts on breathing 100% O2 for 2hours at 50 fsw?

JBD,

The chamber runs that are most common (Table 6, for example) take the patient to 60 fsw equivalent on pure O2, but the patient is in a dry warm chamber, with an attendant who can remove the Bibb mask or Oxy-hood if there is a problem which immediately exposes the patient to air.

If you are talking about an in-water exposure of that magnitude, for your self or anyone else, I would have to strongly suggest that you not allow it to happen! :11:

 

[jbd]

since I know trolling isn't your style and I know that being a NAUI instructor you would know better, I'm trying to figure out why you are asking. Are your going to give us a hint?

Indeed, I do know better although some interesting responses were made.

Now for the rest of the story.

I watched a segment of Deep Sea Science about recovering the turret of the USS Monitor. ( I now know I missed my calling in life) One of the things talked about briefly was the decompression requirements for the divers. They were put into a chamber, pressurized to the equivalent of 50 fsw and breathed 100% O2 for two hours. While this raised some alarm bells for me I immediately wondered how something like this might be misunderstood and end up being tried in the water by someone.

I know that many of us are aware of the fact that the media frequently makes a mess of things when reporting scuba accidents and deaths in regards to breathing O2 but it would seem to me that documentary shows would be a bit more accurate. Along these lines I thought maybe the writer wasn't aware of the possibility that the divers might be breathing a 50% mix for awhile and then switching eventually to 100% when the pressure was lower. Then again I consider these shows to be more accurate so maybe they were accurate in saying that 100% O2 was used for the entire 2 hours. Some of the responses indicate that may well be true.

These are Navy divers with all the bells and whistles available.
Any information on the actual procedures for this kind of decompression would be sincerely appreciated.

 

[tndiveinstruct1]

I watched a segment of Deep Sea Science about recovering the turret of the USS Monitor. ( I now know I missed my calling in life) One of the things talked about briefly was the decompression requirements for the divers. They were put into a chamber, pressurized to the equivalent of 50 fsw and breathed 100% O2 for two hours. While this raised some alarm bells for me I immediately wondered how something like this might be misunderstood and end up being tried in the water by someone.

I know that many of us are aware of the fact that the media frequently makes a mess of things when reporting scuba accidents and deaths in regards to breathing O2 but it would seem to me that documentary shows would be a bit more accurate. Along these lines I thought maybe the writer wasn't aware of the possibility that the divers might be breathing a 50% mix for awhile and then switching eventually to 100% when the pressure was lower. Then again I consider these shows to be more accurate so maybe they were accurate in saying that 100% O2 was used for the entire 2 hours. Some of the responses indicate that may well be true.

These are Navy divers with all the bells and whistles available.
Any information on the actual procedures for this kind of decompression would be sincerely appreciated.

I seem to recall that the divers doing the majority of the work on the Monitor were saturation divers.

Here's a link over to a NOAA site written by the supervisor of diving operations:

http://oceanexplorer.noaa.gov/explorations/monitor01/logs/jun30/sat_dive.html

Hope this helps....

Randy Cain

 

[rmediver2002]

I seem to recall that the divers doing the majority of the work on the Monitor were saturation divers.

Here's a link over to a NOAA site written by the supervisor of diving operations:

http://oceanexplorer.noaa.gov/explorations/monitor01/logs/jun30/sat_dive.html

Hope this helps....

Randy Cain

Much of the work on the most recent Monitior project was completed by saturation divers. There was also many "sprint" diver diving on "surface decompression with oxygen" profiles (about :20 minutes of bottom time per dive)

For surface decompression with oxygen the divers will either do very short in water stops or on less strenuous tables no water stop.

The surface crew then has 3:30 minutes to undress the divers and get them into the chamber, the chamber is compressed to 40 feet sea water (equivilent depth) at a rate of 80 feet per minute :30 seconds max.)

The diver breathe 100% oxygen at this decompression stop but take a :05 minute air break for every :30 minutes of oxygen breathing (breathe air instead of 100% o2 - this time does not count towards the decompression obligation)

The reporter got the chamber depth incorrect, all the decompression is at 40 FSW but other than that the statement is accurate.

 

[Curt Bowen]

Indeed, I do know better although some interesting responses were made.

Now for the rest of the story.

I watched a segment of Deep Sea Science about recovering the turret of the USS Monitor. ( I now know I missed my calling in life) One of the things talked about briefly was the decompression requirements for the divers. They were put into a chamber, pressurized to the equivalent of 50 fsw and breathed 100% O2 for two hours. While this raised some alarm bells for me I immediately wondered how something like this might be misunderstood and end up being tried in the water by someone.

I know that many of us are aware of the fact that the media frequently makes a mess of things when reporting scuba accidents and deaths in regards to breathing O2 but it would seem to me that documentary shows would be a bit more accurate. Along these lines I thought maybe the writer wasn't aware of the possibility that the divers might be breathing a 50% mix for awhile and then switching eventually to 100% when the pressure was lower. Then again I consider these shows to be more accurate so maybe they were accurate in saying that 100% O2 was used for the entire 2 hours. Some of the responses indicate that may well be true.

These are Navy divers with all the bells and whistles available.
Any information on the actual procedures for this kind of decompression would be sincerely appreciated.

When I was on the 2001 USS Monitor project, we assisted the surface supplied salvage divers with video and lighting.

A standard practice for them was to bring thier divers slowely up to 50 feet then yank them up very quickly to the deck of the ship, strip off their suits and slam them back down to depth inside a chamber on the deck of the ship.

We did all our decompression in the water since we were on open curcuit.

They placed their divers on O2 at 50 feet, but it was also a controled environment and a chamber doc was inside with them.

 

[rmediver2002]

The divers are diving on standard mixed gas (hemium oxygen) protocol using surface decompression using oxygen.

When diving deeper than 200 FSW the O2 percentage is less than 16% so the divers are switched to bottom mix in the water column.

On acent the divers are switched to 60% helium and 40% oxygen mixture at 100 FSW (this is optional on dives shallower than 200 FSW), then to 100% oxygen during the decompression stop at 50 FSW (if no 50 FSW stop is made then this switch to 100% O2 occurs at 40 FSW)

The divers complete the 50 fsw stop and then travel to 40 FSW, ascent from this point is controlled and does not exceed 40 feet per minute.

The diver has a total interval from leaving 40 FSW in the water until reaching 40 FSW in the chamber of no more than :05 minutes.


Recompression is completed inside the chamber on deck, for normal operations with more than one diver the divers will observe each other for signs of CNS O2 toxicity in the chamber.

For some projects an additional diver with no decompression oblgation will be locked in to observe the decompression.

For treatment tables an inside tender being either a qualified supervisor or dive medical technician is used.

Dive medical officers are locked in to evaluate the patients as needed but normally kept on no decompression tables so they can respond to any other casualties as needed.

It is not at all uncommon for people not directly involved with the operations to confuse terminology and protocol used, this is often the case when the material is reported in the media.

 

[SueMermaid]

I was watching this same documentary the other night and had the same question.

Forgive my ignorance, but what do the sat divers breathe? I am assuming they stayed at the ~225 feet for a week or more?

My fiancee asked me what their mix is, and I don't know enough about the subject to answer.

And Curt, (I'm gonna show my ignorance again here), when divers were brought up from 50' and recompressed in chambers on deck, what kept them from getting severely bent in the few minutes from the time they left the water till their chamber ride? That sounds like it's an extremely perilous practice. Why didn't they just do long hangtimes?

 

[rmediver2002]

Well I know the question was posed to Curt but for US Navy saturation diver the oxygen percentages are kept from .44 to .48 atmospheres absolute O2.

In emergency situations percentages up to .6 ata can be used but the exposure must be less than 24 hours.

In saturation diving percentages of signifigant concern is pulmonary O2 toxicity.

As far as the surface interval, that is why the maximum time from water stop to chamber stop is :05 minutes, if this time is exceeded or the diver has any symptom no matter how minor the decompression protocol is aborted and the diver is treated for decompression sickness (TT-5 or TT-6)


The water is the least desirable place to decompress the divers, especially on 100% O2. Evrything is about maximising the diver bottom time while minimizing decompression obligations, this is accomplished by decompressing the divers on 100% O2 on the surface in a controled (temperature, depth, gas percentage) environment.

 

[SueMermaid]

Thanks Jeffrey!
I really oughta read more about deco physics and principles. Have I mentioned lately how valuable a resource you all are on this forum?