The Use of Austenitic Stainless Steel versus Monel (Ni-Cu) Alloy in Pressurized Gaseous Oxygen (GOX) Life Support Systems.

Gaseous oxygen GOX must be stored at pressures up to 24 MPa 3500 psi to provide the flow rates required to support the metabolic needs of a diver. A review of the literature concerned with materials compatibility in pressurized oxygen systems were conducted, with emphasis on metallic structural materials. Review of experimental and theoretical work on combustion of austenitic stainless steels and nickel-copper alloys revealed a consensus that Monel nominal 63 Ni-34 Cu is preferred in high pressure oxygen systems, when its strength and weight are acceptable. At the intermediate pressures, 0.7 to 10.3 MPa 100 to 1500 psi, the relative safety of stainless steel as a structural material is unclear, This thesis reviewed the following testing methods friction rubbing, particle impact, fresh metal exposure to heated flowing GOX, promoted ignition and resonance. An experimental apparatus was used to simulate the conditions of GOX flow found in an operational diving set and to compare the flame propagation rates for austenitic stainless steel AISI 316, Monel 63 Ni -34 Cu and carbon steel AMS 5050 tubing in this environment. Keywords Flame propagation rates Breathing apparatus Diver equipment.