Eyeglass inserts aren't considered part of the system and are specifically addressed in the test standards. All of the major SCBA manufacturers certify their SCBA with their inserts anyway.Quote:
NIOSH certfies only the EXACT item they test. In theory, if the SCBA facepiece did not include glasses inserts, then using them voids the NIOSH rating.
Possibly. I tend to think that the NIOSH testing standard should be addressed to provide leeway for intermixing specification approved cyclinders rather than altering the OSHA enforcement standard.Quote:
OSHA now states only NIOSH certfied equipment is OK. This is the problem area.
Inevitably the issue comes back to liability no matter how trivial the actual assembly appears. Afterall, this is America; land of the fee. ;)Quote:
Cylinders are well regulated by the DOT. It is a trivial to install a proper valve into a tank and it is trivial to ensure a proper physical size.
Look, you can put the cheaper version of the same bottles on your packs and just know that you've picked up the liability if the bottle is found to have caused the failure. It appears that many expect the manufacturer to do this, why not assume it yourself if you beleive the risk is so low?
Isn't it funny how we all hate lawyers until we need one ourselves? Then we really don't care how they do it as long as in the end we prevail.
And no, I am not a lawyer. But I do have a really good one who has done me right over the years.
BTW - that spec is published in the DOT test standards which every cylinder manufacturer and hydro test facility is required to have. Valves are pulled at hydro and re-assembled so I fail to see your point about manufacturer control.
Then again - since I service sport diving regulators, tank valves and do visual inspections for steel and AL tanks (though not composites), I probably don't know very much......
As I said before - this issue is NOT rocket science. Everything we are talking about is simple technology. This should be changed. (I do agree though - so long as OSHA has the interpretation it has, its an open/shut case on what you have to do right now - follow OSHA - whether it makes sense or not)
If you use the wrong o-ring, this happens. If you fail to seat the o-ring, that could happen. If the valve assembly is not assembled correctly, this could happen. Its quite possible some cylinder valves are more sensitive to exact torque specs than others but I would bet it was more than just the torque set on the valve - more likely not tightned at all.
The key to my point was that non-SCBA manufacturers are expected to service these valve/cylinder combinations during thier service life so the notion than only the manufacturer is capable of doing so is bunk.
I'm betting that if there was a failure and the non-manufacturer certified person who installed the valve failed to torque the assembly properly, said manufacturer would walk away (more like run!). If the approved person failed to properly torque it? I'd guess they'd be unemployed. So depending on your perspective, it might very well be pretty damn critical.
My limited understand of the torque spec is that it prevents over tightening which can crack the cylinder at the neck along with damaging the O-ring as was noted.
Now for medical tanks with the CGA 870 valve:Quote:
We recommend that all straight thread valves be installed in Luxfer high-pressure aluminum scuba cylinders with a torque recommended by the valve manufacturer for aluminum cylinders.
Without a recommended torque from the valve manufacturer,we would recommend a torque of 50 lbf-ft, plus or minus 10 lbf-ft. All torquing should be done such that valve, valve components and cylinder are not damaged.
Basically - this is a cylinder manufacture who gives a baseline range for valves from other manufacturers - with a plus/minus 10 ft-lb range and then proceeds to give an exact value for a valve/tank combination they have and describe the ramifications for failing to adhere to it. The SCBA tanks luxfer makes out of Al have the 50ftlb ±10ftlb torque spec - or 40-60ftlb range and the 'non-critical' comment I have made above. Conversely, the 870 tanks have a specific 75ftlb requirement.Quote:
Luxfer has extensive experience with new aluminum and composite cylinders, as well as new valves of the standard 870 post-type valve design for oxygen. For such new equipment, Luxfer recommends a torque value of 75 ft.-lbs. However, under certain circumstances described below, this torque value may not apply.
Thus, Luxfer’s current recommended torque value of 75 ft.-lbs. applies only to the installation of a new standard brass, straight-threaded, nickel-coated 870 post-type valve with an approved o-ring into a new Luxfer oxygen cylinder. The o-ring makes a seal in a seat that Luxfer has machined into the cylinder opening. Since Luxfer seat dimensions may differ from those used by other aluminum cylinder manufacturers, Luxfer’s recommendations only apply to Luxfer cylinders. The o-ring material and size are critical for a leak-tight seal—not just any o-ring will work properly with a Luxfer cylinder. In fact, with valve types that use a metal o-ring, if the o-ring is installed incorrectly, gas will leak from the cylinder no matter what torque is applied.
Every tank and valve combination has this information on file with the DOT. A properly trained tech will have access to these references to know how to set the torque on the valves - especially since hydro testing requires valve removal.
I still don't see how using a tank made to a spec but not by the same manufacturer as the SCBA can been seen to be dangerous.
I price war like that could put this country in deeper recession and fire departments would have more money, or be able to buy new tanks they couldn't before. Oh the same of it all. lol