IRON
AND
COAL
AND
COAL
defined by
R = 5 (rate of consumption of wood in fire)
(rate of supply of air to fire)
5 Ib of air being required for the complete combustion of 1 Ib of wood having a typical moisture content.
If R < 1 there is an excess of oxygen in the products of combustion so that the fire is oxygen-rich; if R > 1 the volatile products from the heating of wood are in excess in the products of combustion and the fire is fuel-rich. A transition from an oxygen-rich to a fuel-rich fire condition in a flammable lining of a mine roadway greatly increases the hazard, as the rate of advance of the fire becomes very much greater and high concentrations of toxic gases and vapours are produced with reduction of oxygen concentration downwind of the fire almost to zero.
CONCLUSIONS
If R < 1 there is an excess of oxygen in the products of combustion so that the fire is oxygen-
CONCLUSIONS
The investigations made by the officials and rescue teams have led to the assumption that the fire originated somewhere in the vicinity of the main haulage plane in the S.51 district return. Under normal conditions this roadway was ventilated by some 50 000 ft/min of air. It was heavily timbered and Fig. 4 shows that there was a total quantity of 262 gal of oil present, mainly in electrical equipment. The estimated weight of timber was some 390 tons of heavy board distributed over 510 yd of 14 ft arched roadway. Additionally, some 140 tons of timber had been used to line the remaining 250 yd of road towards the outbye end.
Although no particular cause was officially attributed to the start of the fire, the most popular unofficial cause was placed on a faulty oil-filled transformer. As an electrical engineer well versed in the mechanics of electrical systems protection techniques, should this have been the case, then my comment is that a prime suspect would have been the protection discrimination settings (overcurrent and short circuit settings, primarily by means of fuses) which may not have been set/sized to enable the electrical system to “trip” thus isolating the faulty item of equipment from the electricity supply and preventing damage /fire.
Although no particular cause was officially attributed to the start of the fire, the most popular unofficial cause was placed on a faulty oil-
Authors
G. ROBINSON, B.SC., C.ENG., FELLOW (AGENT MANAGER, OGILVIE COLLIERY)
R. A. EVANS. C.ENG., FELLOW (DISTRICT RESCUE STATION MANAGER)
G. D. MORGAN, PH.D., F.INST.P., ( ASSISTANT REGIONAL CHIEF SCIENTIST, WALES)
E. G. ADAMS. F.P.S.. PH.C. (SENIOR CHEMIST REGIONAL SCIENTIFIC CONTROL, WALES)
R. A. EVANS. C.ENG., FELLOW (DISTRICT RESCUE STATION MANAGER)
G. D. MORGAN, PH.D., F.INST.P., ( ASSISTANT REGIONAL CHIEF SCIENTIST, WALES)
E. G. ADAMS. F.P.S.. PH.C. (SENIOR CHEMIST REGIONAL SCIENTIFIC CONTROL, WALES)