KWS,
I suggest you check the DOT website for their numerous interpretations all requiring cylinder cleaning at 23.5%O2 if you want to transport the cylinder in the USA.
Here is a link:
PHMSA - Interpretations by Date - Interpretation #11-0175
Also, if you want to use a continuous flow system with an oil filled compressor, you are required to get a letter from the compressor manufacturer stating that the compressor is safe to use with 100% O2. I know of no manufacturer who will give such a letter.
From OSHA:
d)
Using a compressor. This proposed condition specified that when employers produce nitrox breathing-gas mixtures, and before using a compressor in which the gas pressure in any system component exceeds 125 psi, they must ensure that: (i) Compressor manufacturers certify in writing that the compressor is suitable for mixing high-pressure air with the highest O
2 fraction used in the nitrox breathing- gas mixture; (ii) compressors are oil-less or oil-free and rated for O
2 service, unless the employer complies with the requirements of condition (e) below; and (iii) compressors meet the requirements specified in paragraphs (i)(1) and (i)(2) of § 1910.430 whenever the highest O
2 fraction used in the mixing process exceeds 40% by volume. In the proposal, OSHA stated that the purpose of these proposed requirements was to prevent O
2-accelerated explosions during the mixing process, the risk of which increases when gas pressure in a system component exceeds 125 psi.
As the highest O2 fraction used in the mixing process is pure O2 diluted then to 32-36% and then passed through the compressor, one must meet the requirements of (i)1 and (i)2 of 1910.430.
OSHA revised paragraph (i) of this condition to indicate that the requirement specified in this paragraph is the responsibility of the compressor manufacturer, not the employer, but is adopting paragraph (ii) in the final rule as proposed. These provisions will provide assurance that a compressor's components cannot serve as an ignition source for an O
2-accelerated explosion.
As OSHA noted in the proposal, oil-based lubricants used in compressors contain hydrocarbons that can ignite in the presence of an enriched O
2 environment during the mixing process; such ignition may cause an explosion that injures and kills employees. To prevent the injuries and death that could result from such explosions, the proposed requirements were designed to ensure that the high-pressure O
2 being pumped through the compressor is free of combustible hydrocarbons. Therefore, paragraph (i) of the proposed condition specified a requirement that employers use hydrocarbon-free air when mixing nitrox breathing gases. By obtaining the manufacturer's written certification that the compressor is suitable for this purpose, as required by paragraph (ii), the employer knows that system components exposed to high O
2 will be safe for mixing high- pressure air with the highest O
2 fraction used in the nitrox breathing-gas mixture. OSHA revised this provision slightly to indicate that providing documentation of a compressor's suitability is the responsibility of the manufacturer, not the employer.
The president of Machine Design & Fabrication, Inc., Mr. Tom Grubb, submitted comments regarding compressors that use synthetic lubricants (Ex. 5-3). After noting that most compressors used for mixing breathing gases use synthetic lubricants (usually diester or triester based), Mr. Grubb argued that the final rule should treat these compressors in the same fashion as oil-less or oil-free compressors. In doing so, he asserted that compressors that use synthetic lubricants have flashpoints and autoignition temperatures that are higher than the operating temperatures of the compressors, thereby eliminating the risk of hydrocarbon contamination of the breathing gas. He concludes that these compressors are as safe as oil-less and oil-free compressors when operated according to the manufacturers' specifications regarding maximum temperature, cooling, ventilation, and maintenance.
Mr. Grubb raises an issue regarding the safety of synthetic lubricants that OSHA did not address in the proposal. As the regulated community has not had an opportunity to comment on this issue, the Agency is not in a position at this time to act on Mr. Grubb's recommendations. Therefore, for the purposes of the alternative procedures permitted by this final rule, employers who operate compressors that use synthetic lubricants are to treat these compressors in the same fashion as oil-lubricated compressors.
In addition, Mr. Grubb noted the importance of using compressor systems according to the manufacturers' specifications. Under the certification requirements in proposed conditions (d)(ii), (e)(ii), and (e)(iv), manufacturers are responsible for providing the user with information on how to use their equipment safely and appropriately. Therefore, the Agency is adding the phrase "when operated in accordance with the manufacturer's operating and maintenance specifications" to these provisions.
(f)
Compliance with other OSHA standards. Under this proposed condition, employers must ensure that SCUBA equipment in which either nitrox breathing-gas mixtures or pure O
2 is under high pressure (
i.e., exceeding 125 psi) complies with the requirements of paragraphs (i)(1) and (i)(2) of § 1910.430. OSHA is including this condition in the final standard as proposed because it ensures that this equipment is free of ignition sources that could cause an O
2-accelerated explosion. As noted above in the discussion of Condition 3(d)(iii), the Agency believes that paragraphs (i)(1) and (i)(2) of § 1910.430 reduce this risk by requiring employers to use diving equipment designed for O
2 service and to clean the equipment of flammable materials before such use.
Additionally,
(e)
Oil-lubricated compressors. Before the employer produces nitrox breathing-gas mixtures using an oil-lubricated compressor to mix high-pressure air with O
2, and regardless of the gas pressure in any system component, this proposed condition would require employers to: (i) Use only uncontaminated air (
i.e., air containing no hydrocarbon particulates) for the nitrox breathing-gas mixture; (ii) have the compressor manufacturer certify in writing that the compressor is suitable for mixing the high-pressure air with the highest O
2 fraction used in the nitrox breathing-gas mixture; (iii) filter the high-pressure air to produce O
2-compatible air; (iv) have the filter-system manufacturer certify in writing that the filter system used for this purpose is suitable for producing O
2-compatible air; and (v) continuously monitor the air downstream from the filter for hydrocarbon contamination.
I am not about all things OSHA, I assure you. MY point is to make yourself aware of Federal Regulations and the penalties if you plan to disregard them. From a litigation standpoint, it is always advisable to follow the Law. If you have a business and are found to be breaking the law, I wish you luck with your insurance policy covering the claim. Having had this conversation with my insurer, I was told "for my policy to be in effect it is understood that I would be abiding by all local, state, and federal laws and regulations."
Fortunately, accidents are few and far between. However, when they occur it is an unpleasant experience being in court, be it civil or criminal as a defendant. Most training agencies will have a little caveat in the S&Ps something to the effect of them saying that some of the standards may fall outside of OSHA and Federal regulations and they do not condone anything outside of workplace safety regulations or Federal regulations.
I encourage you all to make yourselves aware of the Federal requirements as well as all local regulations if you are running a dive business. Bear in mind, the regulations are not the same for the USA, Britain, EU, Australia, Asia, The Islands, etc.... If you want to speed , do it, but do it knowing that you can get in trouble. Also, try not to cause injury to yourself or others.
Good luck and read up.
