Table 2 Early warning index system of goaf fire in coal mine.
From: Research on fire early warning index system of coal mine goaf based on multi-parameter fusion
Development stage | Warning level | Temperature range | Early warning indicators | Index gases characteristics |
|---|---|---|---|---|
Latent stage | Green warning | < 31.7 °C | 100Δ(CO)/ΔO2(%): 0–0.02 | O2 concentration slowly decreases and CO concentration increases slowly |
Oxidation stage | Blue warning | 31.7–54.8 °C | 100Δ(CO)/ΔO2(%): 0.02–0.06 | O2 concentration continues to decrease slowly and CO concentration rises faster |
Critical stage | Yellow warning | 54.8–153.7 °C | 100Δ(CO)/ΔO2(%): 0.06–0.55 C3H8/CH4 > 0 | C3H8/CH4 begins to rise rapidly |
Pyrolysis stage | Orange warning | 153.7–204.5 °C | 100Δ(CO)/ΔO2(%): 0.55–1.55 C3H8/C2H6 > 0 | C3H8/C2H6 begins to rise rapidly |
Fission stage | Red warning | 204.5–241.6 °C | 100Δ(CO)/ΔO2(%) ≥ 1.55 C2H4/C2H6 > 0 | O2 concentration decreases rapidly, CO concentration rises rapidly; C2H4/C2H6 begins to rise rapidly |
Combustion stage | Black warning | > 241.6 °C | C2H2 > 0 | C2H2 begins to appear |
