Habitat check

Demo model
in
PMMA (acrylic) keeps burning on the ISS

75 %

chance a flame keeps spreading, likely 69 to 81 %

Goes outBorderlineKeeps burning
Strong evidenceBased on 85 flight tests of PMMA (acrylic) between 19 to 23 % O2.
See the tests on the map
Closest tests in orbit
Same material, nearest oxygen and flow.
TestSampleO2FlowOutcome
BASS-II B8thin sheet21 %10 cm/sburned
BASS-II B13thin sheet21 %10 cm/sextinguished at low flow
BASS-II B15thin sheet21 %10 cm/sburned
BASS-II M15slab21 %10 cm/sextinguished at low flow
BASS 30sphere20.9 %10 cm/sextinguished at low flow
All tests
What would stop it
  • Switch to Nomexsame atmosphere-4332 %
  • Stop ventilationflow to 1 cm/s-4233 %
  • Lower oxygen more−4 points of O2-2253 %
  • Lower oxygen−2 points of O2-1065 %
  • Lower pressure−0.1 atm, same O2 %-669 %
  • More ventilation+10 cm/s075 %
What the reports say about PMMA (acrylic)
Oxygen and pressure limits
17.5 % O2 (PMMA rods, opposed-flow spread, microgravity; 19 in normal gravity)
“While in microgravity, flame spread was observed at O2 concentrations as low as 17.5 percent, in normal gravity, flame spread was not observed below 19 percent.”
BASS-II Summary Report.pdf, page 58
Oxygen and pressure limits
13.5 % O2 (PMMA rods, stagnation flow, microgravity; upward spread limit in normal gravity 15.4)
“The minimum O2 concentration of 13.5 percent O2 at a of 8 to 12 s-1 is significantly lower than the observed upward flame spread limit of 15.4 percent O2”
BASS-II Summary Report.pdf, page 84
Oxygen and pressure limits
16.4 % O2 (PMMA rods, opposed flow at any flow, microgravity: no spread below)
“opposed-flow flame spread was not observed below 16.4 percent O2 at any flow”
BASS-II Summary Report.pdf, page 81
Ignition
14.5 % O2 (PMMA rods; flames already burning survived down to 13.6)
“that fall below the ignition limit of ~14.5 percent O2.”
BASS-II Summary Report.pdf, page 76
All 22 findings on PMMA (acrylic)