Supplementary material from "Influence of high altitude on the burning behaviour of typical combustibles and the related responses of smoke detectors in compartments"

Point-type light scattering photoelectric smoke detectors and ionization smoke detectors were used for 4 kinds of EN54 fire tests, including 2 kinds of smouldering fires with wood (test fire No. 2 in EN54 standard or TF2) and cotton (TF3), and 2 kinds of flaming fires with polyurethane (TF4) and n -heptane (TF5).

First, the influence of altitude or ambient pressure on mass loss for smouldering combustion (TF2 or TF3) was insignificant, while a significant decrease in the mass burning rate was found for flaming tests (TF4 and TF5) as reported in our previous studies. Second, for photoelectric smoke detectors in flaming fire tests, the effect of altitude was similar to that of the burning rate, whereas for the ionization smoke detectors, the response signal at high altitudes was shown to be ‘enhanced’ by the detection principle of the ionization chamber, leading to an even larger value than at normal altitude for smouldering conditions.