Nitrox workshop dings - Divers Alert Network

Rubicon Foundation Archive (http://rubicon-foundation.org)EVALUATION OF CONTAMINANT-PROMOTED IGNITION INSCUBA EQUIPMENT AND BREATHING-GAS DELIVERY SYSTEMSElliot T. ForsythWendell Hull & Associates, Inc.1631 S. Delaware Ave.Tulsa, OKLAHOMA 74104 USARobert J. DurkinNASA Johnson Space CenterFlight Crew Support DivisionHouston, TEXAS 77058 USAHarold D. BeesonNASA Johnson Space CenterWhite Sands Test FacilityP. O. Box 20Las Cruces, NEW MEXICO 88004.USAAs the underwater diving industry continues to use greater concentrations ofoxygen in its scuba systems, contaminant ignition becomes of greater concern. Inthis study, several scuba component assemblies from the Neutral Buoyancy Lab atNASA Johnson Space Center were tested after 1 year of use. They werepneumatically impacted with 50 percent nitrox gas at 20.7 MPa (3000 psi) toevaluate their ignition resistance then disassembled to assess their cleanliness. Afollow-up study was then conducted on the ignition thresholds of hydrocarbonbasedoil films in oxygen and nitrox environments to characterize the cleaningrequirements for these systems. Stainless steel tubes were contaminated to knownlevels and tested by pneumatic impact. Ignition was determined with a photocellconnected to the end of the contaminated tube. The results of the scubacomponent tests, cleanliness evaluation, and contaminant ignition study arediscussed and compared for 50 percent nitrox and 100 percent oxygenenvironments.IntroductionSince the inception of scuba diving, breathing-gas mixtures for these applications havetraditionally been pressurized air. However, in recent years, as the various advantages of oxygenenrichedgas mixtures for scuba have been discovered, more systems are being developed and157