At 20.9% O₂ and 101.4 kPa (14.7 psia), with 10 cm/s ventilation, the nearest comparable test is BASS-II · row 100 (3/8" clear rod)[2] on oxygen and pressure only; flow not recorded , matching on every compared axis. Differences are test minus scenario; one unit = 2 pts O₂, 25% pressure or 5 cm/s flow. Best fully-compared test: SAFFIRE-I · row 1 [3] 2.02 (NEAR). Its pressure is nominal (stated), not measured.
Gaps to the nearest test (partial match) Axis Gap in scale units Physical difference O₂1 unit = 2 pts ±0.00 (±0.0 pts) Pressure1 unit = ×1.25 −0.00 (−0 %) Flow1 unit = 5 cm/s not recorded · not compared —
D = √(Σ gap²) = 0.00 on 2 of 3 axes. Signed as test minus scenario.
Gaps to the best fully-compared test Axis Gap in scale units Physical difference O₂1 unit = 2 pts +0.30 (+0.6 pts) Pressure1 unit = ×1.25 −0.00 (−0 %) Flow1 unit = 5 cm/s +2.00 (+10.0 cm/s)
D = √(Σ gap²) = 2.02 on 3 of 3 axes. Signed as test minus scenario.
Published evidence is off: only PSI run-table rows are counted.
15% of the charted window lies within D 2.5 of comparable evidence (computed on a 120 × 90 grid; uniform in log pressure).
Investigations, ranked for this question R is computed (proximity, hazard match, scale, coverage, measures). Hover or select a row to find its runs on the field.
1 BASS-II D min 0.00R 872 SAFFIRE-II D min 2.02R 603 SAFFIRE-I D min 2.02R 604 SAFFIRE-III D min noneR 355 BASS D min noneR 296 ACME BRE D min noneR 247 ACME/Flame Design D min noneR 98 SAME-R D min noneR 9P proximity · H hazard · S scale · C coverage · M measures
Compare all investigations, their runs and sources
Findings checked against primary sources MEASURED checked against primary source · human sign-off pending
On the ISS, PMMA rods in low-speed forced flow kept burning at a lower O₂ than the 1-g upward-spread limit reported for the same material.
13.5% vs 15.4% O₂ · BASS-II, cast PMMA rods in concurrent flow, minimum of the flammability boundary at stretch rate 8–12 s⁻¹; the 1-g value is upward spread with an added 4 cm/s forced flow (Hirsch et al. 2003, as cited in the report)
Scope Cast PMMA rods (radius 0.318–0.635 cm) in the ISS Microgravity Science Glovebox
Not valid for Other materials or geometries; partial gravity; rating any material
“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” Olson et al., BASS-II Summary Report, NASA/TM-20210011385, §6.1.4.4, p. 76 (PDF p. 84) (opens in a new tab)
MEASURED checked against primary source · human sign-off pending
Near the low-O₂ limit, PMMA rods on the ISS took far longer to ignite than the igniter-on time used in the NASA standard test, and ignition limits sat above flammability limits.
up to ≈10× the standard igniter-on time · BASS-II, cast PMMA rods, hot-wire igniter, ISS Microgravity Science Glovebox; ignition attempts of up to 500 s failed at very low O₂
Scope PMMA rods with one igniter design
Not valid for Other igniters, materials or geometries
“The ignition delay time can be up to almost 10 times longer than the NASA STD–6001 standard igniter on time.” Olson et al., BASS-II Summary Report, NASA/TM-20210011385, §6.1.6, p. 89 (PDF p. 97); 500 s attempts §6.1.3, p. 67 (PDF p. 75) (opens in a new tab)
MEASURED checked against primary source · human sign-off pending
Without buoyancy to carry it away, fuel vapour from heated samples accumulated and ignited as a sudden deflagration in two Saffire tests.
2 of 5 Saffire IV–V tests · Saffire IV-2 (2-sided PMMA, 100 kPa, 22% O₂, after flow was cut to 5 cm/s) and V-4 (structured PMMA, 72.6 kPa, 25.7% O₂, at ignition in 20 cm/s flow), conditions as in ICES-2021-266 Table 1
Scope Two events in large-scale tests; the authors suggest curled ash upstream may have helped V-4
Not valid for Predicting when or where a deflagration will occur
“Two Saffire samples (IV-2 and V-4) exhibited intense ignition processes of deflagration because of a stratified mixture” Urban et al., ICES-2021-266 (NTRS 20210011521), §III.B, p. 5; V-4 at ignition p. 7 (opens in a new tab)
MEASURED checked against primary source · human sign-off pending
The gravity effect on limiting O₂ depends on the material: Ultem's 0-g limit sat slightly above its 1-g limit, and Nomex's Martian-g limit sat below its lunar-g limit.
Ultem ΔO₂ (0 g) +0.25 · Nomex ULOI* Mars 19.9 vs Moon 21.0 % O₂ · Same drop-tower study: Ultem 1000 at 10.2 psia, Nomex HT90-40 at 14.7 psia; 5.18 s tests
Scope Two charring materials, one thickness each
Not valid for Ranking gravity levels for untested materials
“For these charring materials, the oxygen margin of safety in 0g is very close to zero” Olson & Ferkul, ICES-2012-3492 (NTRS 20130010991), Table I, p. 6; charring-material discussion p. 7 (opens in a new tab)