Safety Alert

Ventilation of blind ends

Circulation

Coal Mine Owners
Coal Mine Managers
Coal Mine Unions
Inspectors

Safety Circular

Dear Sir,

At a large coal mine a plug of up to 4% firedamp passed through a booster fan when a gas fast heading on the intake side of the booster was degassed in an uncontrolled manner. The auxiliary forcing fan to the heading was restarted by an electrician who had been sent to restore power to monitoring equipment. The incident could obviously have had very serious consequences.

Investigation revealed that the auxiliary fan, which was sited on the return side of a new working face, had been turned off due to periodic firedamp levels in excess of 1.25% which had repeatedly tripped the fan's Cardowan protection.

The fan was stopped but not properly isolated.

At the time of the incident the fan had not run for over a week and firedamp had built up in the heading. The fan had not been isolated and inspection reports had failed to highlight the deteriorating situation in the heading.

The Main Points to note are:

All parts of the mine except wastes are required to be adequately ventilated unless stopped off.
If ventilation is interrupted proper fences must be erected and action taken to restore ventilation as soon as possible.
Management reporting systems must ensure that information from inspection reports are properly conveyed and action is taken to deal with defects.
Isolation procedures, must be specified and adhered to for equipment which, when operated, may lead to danger.
The supply of electricity must be cut off to electrical equipment, including booster fans, if any person detects over 1.25% firedamp at the place where the equipment is operating
Managers should review the robustness of their own arrangements for managing such situations.

Yours sincerely

S P Wing
HM Principal District Inspector of Mines