An Improved Approach for Analyzing the Oxygen Compatibility of Solvents and Other Oxygen-Flammable Materials for Use in Oxygen Systems

Abstract

Solvents used to clean oxygen system components must be assessed for oxygen compatibility because incompatible residue or fluid inadvertently left behind within an oxygen system can pose a flammability risk. The most recent approach focused on solvent ignition susceptibility to assess the flammability risk associated with these materials. Previous evaluations included ambient pressure liquid oxygen (LOX) mechanical impact testing (ASTM G86) and autogenous ignition temperature (AIT) testing (ASTM G72). The goal in this approach was to identify a solvent material that was not flammable in oxygen. As environmental policies restrict the available options of acceptable solvents, it has proven difficult to identify one that is not flammable in oxygen. A more rigorous oxygen compatibility approach is needed in an effort to select a new solvent for NASA applications. NASA's White Sands Test Facility proposed an approach that acknowledges oxygen flammability yet selects solvent materials based on their relative oxygen compatibility ranking, similar to that described in ASTM G63-99. Solvents are selected based on their ranking with respect to minimal ignition susceptibility, damage, and propagation potential, as well as their relative ranking when compared with other solvent materials that are successfully used in oxygen systems. Based on these comparisons, in which solvents exhibited properties within those ranges seen with proven oxygen system materials, it is believed that Solstice PF, L-14780, and Vertrel MCA would perform well with respect to oxygen compatibility.