ABSTRACT
K E Y W O R D S : Coa l mines, mine fires, spontaneous combustion, sealed-off fire areas, fire status
assessment, fire indicators
1. I N T R O D U C T I O N
Underground fires are one of the serious hazards in coal mines. Fire fighting is often done by seal-
ing off the area containing the fire. After the fire area is sealed, the necessity arises to assess the
fire status, in order to decide whether to open the sealed area. Heterogeneity of the medium makes
it difficult to determinate the physical phenomena occurring in the sealed space. The methods of
fire status assessment depend mainly on gas samples taken from the sealed area and analyses of
their composition. The various methods of fire status assessment are based on fire indicators,
which are calculated from the concentrations of fire gases in the samples. K n o w n fire indicators are
not always correctly used and not always describe the status of the fire contained in a sealed area
properly. The changes of fire indicators' values in time have more significance in the proper inter-
pretation of fire state. U p to now no reliable, practical indicators signalising extinction of a sealed-
off fire has been worked out. A fire may exist in a sealed area from several weeks to several de-
cades. Therefore, proper interpretation of fire status parameters is very important in the safe open-
ing of sealed areas as soon as possible and recovering the locked up coal reserves. Although a ran-
ge scientific investigations were done, there are no unambiguous criteria for assessing the fire sta-
tus and the problem is still not solved.
