Electrical Arc Ignition Testing of Spacesuit Materials

Abstract

A frayed wire was found inside the extravehicular mobility unit (EMU) spacesuit, which led to concerns that it may be possible to ignite materials in the EMU by electrical arcing. As a result, the NASA Johnson Space Center (JSC) White Sands Test Facility was requested by JSC to conduct arc-ignition tests on multiple EMU materials placed in varying oxygen concentrations. Because understanding the ignitability of materials requires simulating the worst-case scenario, three test methods were developed to understand what conditions were the most severe. The most severe method was then used to characterize the materials presently used in the EMU by determining the minimum levels of current necessary to initiate combustion at a given voltage. These arc-ignition tests were performed in 100 % oxygen at 23.5 psia and in 50 % oxygen at 50 psia. The following materials were tested: cotton fabric; polyester fabric; polyurethane cable jacket; Gore-Tex® woven polytetrafluoroethylene (PTFE) fabric; nylon/Lycra® knit fabric; moleskin; nylon/spandex knit fabric; nylon tricot fabric; cotton-flocked Rucothane;® urethane-coated nylon; Kerlix® cotton dressing, Estane® polyurethane; and Capilene® hollow fiber polyester fabric.

Clean Agent Suppression of Energized Electrical Equipment Fires

“…Recent National Aeronautics and Space Administration (NASA) tests, using three different models of damaged-wire ignition, evaluated the current necessary for hot-wire ignition of space suit materials [59]. Test data were presented for a range of wire sizes, polymeric materials, and surface conditions.…”

“…NASA WSTF Tests for EVA Suit Wire-Failure Ignition: Recently, NASA technicians examining an Extra-terrestrial Vehicle Activity (EVA) suit which had just been returned from space, found frayed wires [59]. The wires could have been an ignition source during an EVA, with severe consequences in the oxygen-enriched environment of the suit.…”

The effects of strain rate and temperature on commercial acrylic artist paints aged one year to decades

“…The brittle-ductile transition is evident in failure strain data from the tensile experiments, showing a change of more than two orders of magnitude across the T g . The application of TTS is usually restricted to small strain tensile data; however, Smith [44][45][46][47] showed the method applied to the ultimate properties of rubber materials. A similar approach was taken in this work, where failure strain mastercurves were constructed by shifting the average strain rate, R a , from the constant • C for one-yearold and 27 year-old paint films.…”