The Inquiry into the causes and circumstances attending the explosion at the Sneyd Colliery, Staffordshire on the 1st January 1942, was held by Sir Henry Walker, C.B.E., LL.D., in the Town Hall, Hanley on the 13th April and lasted for four days, taking evidence from thirty five witnesses. All interested parties were represented and the report was presented to Major The Right Honourable G. Lloyd George, M.P., Minister of Fuel and Power on 2nd November 1942.
The conditions in the crut after the explosion were described at the inquiry. Near the bottom many tubs were overturned but some were on the rails. There were three tubs just above the bottom and on the outbye side of theses a stone which measured 6 feet long by three feet wide by three feet thick was found standing on one end on the floor and the other against the roof from which it had fallen. It blocked the empty road but not the full road.
Travelling up the jig a stone was found on the floor and then a rope cap on the empty side. On the right side there was a damaged air pipe flange and then a hole in the roof from which the stone found down the jig had fallen. On the right side of the full road there was a tub coupling chain and further up in the empty road, one end of the jig rope with it’s cap and coupler. About five yards further inbye on the right side of the road there was the electric cable which was damaged. The gland that was fixed to the compressed air pipe was found to damaged a little further along the crut and in the full road at the other end of the jig rope was found without it’s cap. The two Warwicks were found in a normal condition and on the outbye side of them past the brow of the jig and lying on the empty road was the jig wheel which had been moved 8 feet to the left of it’s normal position.
From the evidence of the damage in the Banbury Crut Jig, deductions were drawn about the explosion. Mr. Harry Cook, the undermanager stated that after the explosion he found no signs of any coal cutting or shotfiring having taken place on that morning. There was no unusual smell or sign of spontaneous combustion or if the ignition of firedamp but he found evidence of a runaway set of full tubs which had careered down the main jig and had damaged the compressed air pipe in which there was a pressure of 80 lbs. per square inch and the electrical cable was found to have been damaged. It was established that the tubs were empty when they ran away since no coal or dirt was found lying anywhere on the jig. When asked to say which end of the hauling rope found in the jig had been attached to the full load and Mr. Cook replied-
“The rope in the jig with the coupler and tackle attached would be the one normally attached to the full loads and the one that was broken would be the one that should be attached to the empties.”
The rope cap that was found on the empty side of the road and a six feet length of the rope was examined by Mr. Alexander Esdale McClelland of the Safety in Mines Research Board. He said that a force of 9Å tons was required to pull off the cap from the rope and he said that sparks could have come from the rope when it broke. It was generally agreed that the explosion originated in the Banbury Jig and was one of coal dust alone but there was no agreement either to the origin of the coal dust or as to the source of ignition except that the runaway set of tubs was the original cause. In the opinion of Mr. John Hebblethwaite, the manager, the coal dust had come from the runaway tubs on the jig. He said:-
“After thoroughly investigating and considering all possible causes of the explosion, I have come to the conclusion that six tubs were turned in at the top of the Banbury Crut Jig without any empty wagons being attached to the other rope. From some unknown cause the loads at the top of the jig ran away and as these six loads careered down the jig, the oncoming rope possibly got behind one of the wheels. When the impact occurred at the pass-by it would have been responsible for pulling the jig wheel out at the same time breaking the rope. If the tubs were not already derailed this would derail them. A pair of glands covering a half inch square hole in the compressed air main was knocked down the pipes a matter of 6 inches. The escape of compressed air at 18 lbs. per square inch pressure would increase the amount of turbulence already set up by the runaway tubs. Immediately following this, the tubs got rucked up and damaged the power cable, the resulting cloud of dust produced by the rucking of these tubs, due to the force that had been thrown out into the jig, would travel back up the jig, being assisted in doing so by the ventilation which is travelling at 200 feet per minute and when it had almost gone, the finer particles, which were still in an agitated state, due to the turbulence of the compressed air pipe, were, I feel sure, ignited by one of the following causes:-
- "Frictional sparks from the tubs crossing the compressed air main and steel arches at the time when they were rucking up and also from sparks produced from the wheels and the breaking rope.
- Electrostatic sparks from the discharged compressed air.
- Spontaneous electrification of the dust cloud, I feel sure, played some part in making this dust cloud more easily ignited than in normal circumstances.
- The cable, and I have gone into this very fully with people who know a lot more about cables than I do myself, was concerned but I have to come to the conclusion that the cable was not responsible.”
Mr. Edgar Hamilton Frazer, H.M. Divisional Inspector of Mines thought that when the tubs became derailed considerable sparking would occur and that the dust exploded was raise from the floor by the empty rope flying up the jig but Professor Cotton was sceptical that the explosion was caused by friction sparks.
After hearing all the evidence, Sir Henry Walker came to the following conclusions-
1). That the up-going rope got over the inside wheel of the first tub of the set
coming down at the time of a runaway
2). The marks between the strands of the sample of rope examined by Mr. Clelland were made by the rope rubbing against the front right-hand corner of the first tub coming down and that the two small flakes of mild steel he found embedded in the rope came from the bottom of this tub.
3). That the capel of the up-going rope was caught against the sole of this tub and so pulled off, the jig-wheel being pulled down and the set derailed at the same time.
4). That 3) occurred when the first tub on the down coming set was about ten feet
above the cock in the air main.
5). That, thereafter, the derailed tub or tubs displaced the cock and then damaged the electric cable. And I think
a). The dust which was ignited was dust from the jig and not from the runaway tubs
b). That such dust had been ignited before either the hole in the air main had been exposed or the electric cable damaged.
c). That the ignition of such dust was due to heat generated by friction between the up-going rope and the underside of the first down-coming tub of the runaway set.”
The Inspector went on to say
“Even though I do not connect the compressed air main or the electric cable with the origin of this explosion, I think, if such plant has perforce to be laid in such places, it should either be protected by a strong fender against passing tubs or buried, and, in the case of cables, suitably protected to prevent the possibility of damage from picks or other tools.
In the present case, the cable had been removed from the jig. Some better means of preventing runaways is also required and, if possible, they should be automatic. The ‘Warwicks’ at the top of the Banbury Jig seemed to be too near together and were operated more as a matter of routine than a safeguard.
After the disaster the method of working were looked at by the management of the colliery and it was considered to spray the coal at the loading and transfer points.
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