South Yorkshire Times November 2, 1957
Flash From Damaged Cable Was Cause of Barnburgh Pit Explosion
The cause of the Barnburgh Main Colliery explosion in 1. June, in which six men were fatally injured and 14 , others injured, was a flash from a damaged cable, states Mr. C. W. Scott, Divisional Inspector of Mines, in his report to the Minister of Mines, issued on Monday.
In his conclusions, Mr. Scott states:
(1)—It Is obvious that there was a large body or very rich firedamp mixture in the top part of the loading gate between the face ripping and the inbye back ripping immediately before the explosion. The source of this gas was a break in the roof nine feet back from the face of the ripping which probably opened into a gas reservoir sometime after the pre-shift inspection. The quick make of firedamp was obviously too much for the low velocity air current. I consider the ventilation close to the roof would be very sluggish and would offer little resistance to the tendency of the low density methane to layer next to the roof against the general ventilation.
2.—There was strong evidence that the deputy tested for gas 10 to15 minutes before firing the shot. I feel that careful examination should I have revealed gas.
3.—I consider that the flash from the damaged cable was the cause of the explosion. This would have been avoided if the cable had been properly protected in accordance with Regulation 10 of the Coal and Other Mines (Electricity) Regulations, 1956, in which the legal requirements are clearly set out.
4—Examination afterwards showed that the 550 volt switch, because of a mechanical defect of the tripping gear, could not trip on earth fault and overload protection was also unreliable.
5.—Large roadways are required in modern mining and there may be occasions when leakage intakes are difficult to avoid. However, the quantity of air passing along all roadways should be such that velocities near the roof are damp suifficient to prevent layering of firedamp.
40 yard flame
In his report, Mr Scott says that there was evidence of the passage of flame along the full length of the face and outbye for about 40 yards along the left side intake and right side return airways and the conveyor gate from the front ripping lip to point some 50 yards outbye from the place where the shot was fired at the first back ripping. There was no evidence of explosive violence and only very slight coking at widely scattered points.
Microscopic examination of coke particles showed that the coal dust had been coked in situ and had not being coked while raising a cloud. All indications were that the explosion and been one of firedamp and coal dust had played little or no part in its propagation. There was no visible evidence to indicate the probable point of origin of the explosion.
Learning appeared to have been heaviest in the conveyor gate between the in by backing ripping and the face. In this portion of roadway several articles of clothing, and in about 6 feet from the roof, were partially burned or scorched. The seizing on the telephone cables was burnt and blistered and charred paper was found. Outlbye this black ripping burning was confined to the roof.
There were charred articles of clothing and paper found on both faces and also in the right and left-hand gate.
In the left hand gate about 10 Yards from the face an air hose had been on fire and a fire extinguisher had been used to put out the flame.
During the first inspection after the explosion, states Mr. Scott (under the heading of inflammable gas), firedamp was found in explosive quantities in the conveyor roadway and at the left hand side roadway ripping lip against the fault slip. In the conveyor roadway there was three per cent. of firedamp near the roof of the excavation formed at the inbye back ripping where the shot was fired, this being diluted to 1. per cent, at the base of the ripping.
On the inbye side of this ripping, the quantity of firedamp increased near the roof as the face was approached. At 40 yards from the face ripping there was a layer of explosive quality about six inches in thickness and this increased to more than two feet at the ripping lip.
Inspection revealed that firedamp was issuing freely from a backward heading break, nine feet from the ripping lip. The percentage of firedamp in the general body of the air current was very low on all three roadways and on the face, nor could any firedamp be found in the wastes.
When the district was inspected the following day here was still a heavy feeder from break in the centre gate near the face ripping, but gas could not be detected in any of the waste nor at the back ripping. The ventilation been increasing 12 hours earlier.
Mr Scott continued: “The ignition almost immediately followed the firing of the shot, but there soon emerge a possibility that the shot had damaged the electric cable and caused a flash. The shot and the damaged cable were possible sources of ignition.”