Nitrox workshop dings - Divers Alert Network

Rubicon Foundation Archive (http://rubicon-foundation.org)Richardson and Shreeves: Overview of PADI Enriched Air Diver Programback flow into the filling system from an enriched air cylinder. This also poses a potentialfire/explosion hazard in the presence of high oxygen concentrations.The second concern is the percentage of oxygen in the blend. The amount of oxygen in anenriched air blend is critical. If the percent of oxygen varies by more than one percent, oxygenexposure, maximum allowable dive depth and no-decompression limits will be affected.To handle these concerns: If partial pressure mixing in the cylinder will be used, air used infilling enriched air cylinders must meet oxygen compatibility requirements. Oxygen compatibleair is produced by using special oil-free compressors, special filtration, or a combination of both.This is crucial because even trace oil or contaminants may create explosion/fire hazard. Other,more preferred methods of producing enriched air do not require putting pure oxygen in thecylinder. These methods greatly reduce filling hazards, but nonetheless, the cylinder must bededicated for enriched air use and serviced accordingly.Enriched air blending and filling requires keeping records of system maintenance and fillsbeyond those required for a conventional compressed air system. To manage these concerns,enriched air cylinders should only be filled by reputable, qualified enriched air blenders.Qualified blenders have the proper equipment for producing oxygen-compatible air andminimizing contamination of equipment that must remain in oxygen service and/or enriched airservice. Qualified blenders have the special training required to produce accurate enriched airblends and confirm the accuracy. Qualified blenders have been trained to follow the operationalprocedures and maintain the necessary records.Qualified enriched air blenders and service are identified by checking the following:• Gas verification — The operation should be able to show regular analysis of the air ituses for enriched air blending. This air should meet local standards for oxygencompatible air, such as Compressed Gas Association (CGA) Grade E air standards,modified to have no more than 0.1 milligram per cubic metre of detectable hydrocarbonsor 10 parts per million of carbon monoxide (many operations try to limit it to two partsper million), or Grade J standards.• In all cases, the air should be filtered to eliminate detectable particles (dust, etc.).• Proper procedures for cylinder marking, analysis, and record keeping ~ A lack of thesemay indicate that the operation isn't qualified or prepared to properly support enriched airdiving.Oxygen AnalysisEnriched air is analyzed by the blender after blending. Nonetheless, the diver who will beusing a cylinder of enriched air must also personally verify the oxygen analysis of the cylinder.Do not dive with a cylinder of enriched air if you have not personally verified its contents.Failure to verify cylinder contents could lead to DCS or drowning due to oxygen toxicity if thecylinder contains an enriched air blend different from what you believe it to be. This is animportant safety principle that avoids problems by double checking the initial analysis, verifying49