The use of safety related control systems in primary mine ventilation circulation

A description is given of a ventilation problem at a large underground coal mine. The limitation of conventional solutions is discussed, along with the proposed solution using an underground recirculation fan in the primary mine ventilation system. Foreseeable potential hazards associated with the proposals are identified. The authors describe the need for emergency shutdown of the recirculation fan and the use of a programmable electronic system (PES) to monitor and automatically initiate a shutdown in the event of predetermined criteria being exceeded. The system had to be designed to ensure the stoppage of the fan on early detection of adverse conditions, but unnecessary interruption of the ventilation system when conditions were satisfactory had to be minimised. The selection and assessment of the programmable electronics (PE) and the selection and location of suitable transducers to continuously monitor various parameters is outlined. The use of a transducer `voting system´ controlled by the PE to take account of reliability and replacement of transducers is also described