Hardly relevant. 100% O2 in an environment with a multitude of combustibles.
And NASA found that no matter how hard they tried they couldn't get anything to spontaneously fire up in a 50% environment. Sounds like CGA is talking out their oss.
The 40% Rule!
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Hardly relevant. 100% O2 in an environment with a multitude of combustibles.
And NASA found that no matter how hard they tried they couldn't get anything to spontaneously fire up in a 50% environment. Sounds like CGA is talking out their oss.
100% relevant to scuba diving. A lot of research subsequent to that fire led directly to scuba applications. Had that fire not occurred, it is not clear where we would be today in terms of Nitrox and oxygen. It's important to understand our roots.
It's also very hard to believe that the Compressed Gas Association, who sets the industry standards for compressed gasses, is "talking out of their oss."
If you review CGA standards and scuba standards, it appears that the scuba standards are quite lax and sometimes not supported by the facts.
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pescador775
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Nadwidny, I see some partial relevance of the accident. After the conflagration in the simulator, NASA decided to run the launch phase with NITROX, and switch to oxygen while in orbit where the cabin pressure is maintained at a lower level, (for fire prevention and safer decompression for space walks). At least that is what I remember. I guess the accident drove the PP tests of NITROX but not really sure.
I agree that the CGA are risk adverse. There are peer pressure, group dynamics, career interests, empire building, etc involved. There is no career penalty for overstating dangers, however tenuous. A committee decision often has a bland or cautious element, or is just ignorant. In a committee, there may be one dissenter and often this may be a person who knows more about the issue than anybody else but is usually brought into line by the least knowledgeable among them in terms of technical matters but who excels at playing politics, moving pieces around on a board and passing the buck.
In the safety world, the rules evolve through experience; let us cite the EOD, ordnancemen in general, and OP5, the pointy end of the sword and its Bible. That document is written in blood. When somebody gets blown up a new rule gets written in. However, the CGA aren't waiting for the blast, they just write what they want based on govt rules, consultants or sometimes just certifying current industry practice while excluding some things which individuals, particularly divers, are doing, even if in large numbers. The dive industry filled gaps by testing SCUBA tanks laden with water. This is what drove the annual inspection programs and subsequent policy and rules. Some of things that independent actors have been doing could look like competition to others in a similar line of work.
NASA divers started handling NITROX. Later, civilian divers jammed tanks with NITROX while we waited for the blast, but nothing happened. Surely, somebody on the outside noticed the silence. Frankly, I have at least as much and maybe more, confidence in the "Hacker" as I do the CGA. Nevertheless, we owe a lot to the CGA in terms of their wonderfully confusing and idiot proof connectors, (an idiot would never figure them out), and to updating definitions of clean air after industry had achieved the technical means to do so at a reasonable cost. I mean, the diver shops and fire depts were pumping air which was cleaner than the preexisting Grade E definition. Meanwhile, the Euros had already updated EN12021. I suppose that we should be obliged that they usually stay out of the way of divers even as they nitpick us once in awhile. Lately, divers have been encroaching on their turf. It was inevitable when we bought and used more compressors, mixers, oxygen cylinders, connectors and started writing and teaching about this stuff including the contents of CGA's expensive pampflets. Is it any wonder that the CGA curmudgeons have been grumbling?
I agree that the CGA are risk adverse. There are peer pressure, group dynamics, career interests, empire building, etc involved. There is no career penalty for overstating dangers, however tenuous. A committee decision often has a bland or cautious element, or is just ignorant. In a committee, there may be one dissenter and often this may be a person who knows more about the issue than anybody else but is usually brought into line by the least knowledgeable among them in terms of technical matters but who excels at playing politics, moving pieces around on a board and passing the buck.
In the safety world, the rules evolve through experience; let us cite the EOD, ordnancemen in general, and OP5, the pointy end of the sword and its Bible. That document is written in blood. When somebody gets blown up a new rule gets written in. However, the CGA aren't waiting for the blast, they just write what they want based on govt rules, consultants or sometimes just certifying current industry practice while excluding some things which individuals, particularly divers, are doing, even if in large numbers. The dive industry filled gaps by testing SCUBA tanks laden with water. This is what drove the annual inspection programs and subsequent policy and rules. Some of things that independent actors have been doing could look like competition to others in a similar line of work.
NASA divers started handling NITROX. Later, civilian divers jammed tanks with NITROX while we waited for the blast, but nothing happened. Surely, somebody on the outside noticed the silence. Frankly, I have at least as much and maybe more, confidence in the "Hacker" as I do the CGA. Nevertheless, we owe a lot to the CGA in terms of their wonderfully confusing and idiot proof connectors, (an idiot would never figure them out), and to updating definitions of clean air after industry had achieved the technical means to do so at a reasonable cost. I mean, the diver shops and fire depts were pumping air which was cleaner than the preexisting Grade E definition. Meanwhile, the Euros had already updated EN12021. I suppose that we should be obliged that they usually stay out of the way of divers even as they nitpick us once in awhile. Lately, divers have been encroaching on their turf. It was inevitable when we bought and used more compressors, mixers, oxygen cylinders, connectors and started writing and teaching about this stuff including the contents of CGA's expensive pampflets. Is it any wonder that the CGA curmudgeons have been grumbling?
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I guess someone forgot to tell the compressor its OK at 40% LOL
Dykking - bladet for dykkeinteresserte! - Kompressoren eksploderte!
Last weeks explosive installment from the "learn or burn" exponants, Iain
pescador775
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About the Norwegian diver that was injured; he states that he was bending over the compressor to drain the filter canister when the canister exploded. He also notes that the oxygen tank which was feeding the mixer seemed to drain faster than usual and wonders if high oxygen content of the mix was the trigger. An investigation is underway. Apparently, the man was not seriously injured, but was struck by small shrapnel and hot gas.
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Thank you for your responses, useful information!
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32% all the way for the time being...LOL
Killer&Griller
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Conversion to English for those of us having trouble reading the article.
The compressors exploded!
It was the compressor that exploded on Monday evening, not dykkerflasken, 'says Stig Nordeide from his hospital bed on St.Olavs hospital in Trondheim. Fortunately, was not Nordeide hard damaged and took on contact with the Diving to stop some of the speculation taking place.
Nettmedier (including Dykking.no on Tuesday) and forums that have discussed the accident writes that it was a dykkerflaske that exploded. As a result, not accuracy, 'says Stig Nordeide to Diving. It was the compressor that narrow, and the powerful. The compressors moved up several meters in smell, which is about the forces that were in turn ...
-- I was lent over the compressor in order to drain the filters when it smallt, 'says Stig Nordeide to Diving. It was a bad smell, and I was turned over. It was a completely surrealistic and frightening experience. When I began to get to me again I wondered how fælt in my own state was, and how it was gone with my face, among other things. Fortunately, so it værre out the one it was. Øynene was also struck by småsplinter, but they receive no lasting damage it appears, 'says a relieved Nordeide
Nordeide was going to fyllle nitrox for a half-year-old bensindrevet compressor at a 'continues blending' nitrox diaphragm fyllepanel when it narrowly. Nordeide responded that the bottle of pure oxygen that was connected blandepanelet, so appear to be emptied faster than normal. Before he had seen it, so narrow it. If it has happened a mistake here, and that the compressor has received more oxygen in than what it was, and that there was oxygen that exploded, is something that will be investigated now. It is sheer that it was filterhuset on the compressor that exploded. Fortunately, was not Nordeide hard damaged in the accident, but it as just after the smell worse than what it turned out to be. Among other things, was struck Nordeide in the face and the hands of småsplinter from the compressor-smell. Because there a problem with an air ambulance were once indent.
Stig Nordeide from Austevoll has advanced and nitrox sertifisertifikat. The two other divers who were present when it was narrowly respectively minedykker and divemaster and yrkesdykker. Read here what we wrote about the case on Tuesday: Important injured in The picture shows the explosion in the compressor for smaller had moved up a couple of metres from the yellow cart it stood on. All photo: Private.
theITdiver
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Preface:I'm far from the expert, but I am learning fast :14:
Don't forget too, that if you are going to have a partial-pressure nitrox fill, the tank needs to be O2 cleaned as well since it will be filled with pure O2. I know PP fills are rare now and have mostly been replaced by membrane compressors, but a few dive sites here still use them because they are located in very remote country areas. At least around here, they wont do a PP fill if the tank is not O2 clean.
Gilldiver
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PP fills are rare? At least here in the Northeast it is the other way around, membrane and banked seem to be much more rare as they are much more expensive to purchase and operate then a PP system. I know of many shops that have NITROX but only have one or two 300 Cubic Ft bottles in the corner.
As for NASA's use of 100%, it much more for engineering ease of atmosphere control and control of bends cases then anything else. Controlling two gases (O2 and CO2) is much more easy then three (O2, CO2, and N2). But as NASA found out the hard way, 100% at any pressure has hazards and the first Apollo capsule was loaded with combustible lubricants and materials.
As for the BENDS, remember the Apollo astronauts always walking to the launch pad with helmets on? That was because they were on 100% and breathing down their N2 content. After all they were saturated with 79% nitrogen at 15 psi and going into an atmosphere that in flight was going to be around 5 PSI of O2. They had a high likelihood of bubble formation with no treatment except return to Earth. NASA still faces the same problem with space walks as the space suits are only pressurized to 2 or 3 PSI and they are at 15 Psi in the Shuttle or Space Station. They need to breath down (almost decompress, but not quite as they are breathing down with no change in pressure) for 4 to 5 hours before they can exit.
In fact, the Air Force has many more cases of bends then the Navy has due to cabin pressure loss at attitude. The Cargo aircraft have problems as most cargo bays are not pressurized, so the passengers and cargo masters need to go on O2 early. This is of special concerns to SOF high altitude jumps were you just don't want your shooters all bent up before they do their thing.
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