Oxygen Service
Oxgen SERVICE means that a valve, cylinder, regulator or system component is both Oxygen CLEAN and Oxygen COMPATIBLE. This process to bring the item into Oxygen SERVICE is typically done Annually or it is done anytime the item becomes inadvertantly contaminated with any substance or material that is likely to be a FUEL for Oxygen.
Oxygen COMPATIBLE is the removing of components that would provide fuel in a fire situation with oxygen and replacing these components with safer alternatives - this includes special lubricants such as Fomblin (Solvay Solexis, 3606OG, Perfluoro Polyether PFPE), Christolube MCG111 also a PFPE has the NSN 9150-01-364-0218 for the common 8oz tube form) or the thread lubricant which is a black coloured grease - Christolube MCG125 that contains molybdenum disulfide. All parts of the item must be made compatible through replacement of parts to ensure they are inert at the standard and elevated operating temperatures and pressures of Oxygen. Remember Adiabatic heating and sonic flow can cause tremendous rises in temperature do not just assume compatibility at standard operating temperatures. Ensure that kindling of the items is not possible or the risk of such is significantly limited.
Oxygen CLEAN is the removing of all contaminents through effective flushing of a cleaning fluid or solvent that will remove all grease, oil, lint and all other fuel sources and not leave any residue itself. Fluids such as Simply Green and Vertrel specialty fluids are considered more environmentally friendly than the ozone-depleting solvents such as CFC-113, 1,1,1-trichloroethane, HCFC-141b, n-propyl bromide (nPB), HFE solvents and HCFC-225, as well as high-global-warming solvents such as perfluorocarbons (PFCs). However you will see many establishments still using 1,1,1-trichloroethane for its thorough and effective cleaning without residue.
It is fair to say that the procedures for cleaning will vary according to the item, but broadly they have common steps of changing parts to compatible items, stripping down the component, using ultrasonic baths to ensure components are stripped of any hardened residues and aid cleaning (use of other acid cleaning solutions may be necessary as a precursor to O2 Cleaning), then assembly according to manufacturers recommendations and lubricating using one of the above Oxygen COMPATIBLE greases/fluids such as Fomblin - Not SILICONE GREASE (DOW111) nor MOLYKOTE 557.
Once fully assembled and tested then pressure test with CLEAN air and then slowly meter in Oxygen - treat this Gaseous OXYGEN with the respect it deserves. In diving environments, the components and materials in use do not exceed a pressure of 210 Bar with Oxygen. Above this pressure the risks considerably increase, the tribology effects and the material kindling effects change to a level that can cause spontenous oxidation and combustion resulting in an Oxygen Fire or Explosion.
<< Back to ADM Tech Tips for more information and ideas...
Any further help needed Contact Us and we'll pin Andrew down to answer your query.
|