Diesel Discriminating Mine Fire Sensors.
Proceedings of the 27th International Conference of Safety in Mines Research Institutes, February 20-22, 1997, New Delhi; Oxford and IBH Publishing Co. Pvt. Ltd., New Delhi, 1997 1997:1013-1023
Sensors developed by NIOSH to discriminate between diesel exhaust (carbon-monoxide (630080) (CO)) and fire products (smoke) were described. The operating principles behind the development of sensors which detect both CO and nitric-oxide (10102439) (NO) and those that detect smoke were described. The CO/NO sensor continuously monitored both CO and NO levels and calculated the CO/NO ratio. When some NO was measured, the ratio was used to estimate the expected level of CO. The alarm was activated when the actual amount of CO measured exceeded the estimated level by a predetermined amount. The smoke pyrolysis sensor was based on the reburning of fire smoke when passed through a small heated tube and comparing the concentrations of smoke particles in the air to that exiting the heated tube. The alarm was activated when the difference was above a predetermined amount. Diesel exhausts are not affected by passage through the tube. The final sensor described, the optical smoke sensor, operated on the principle that diesel generated smoke particles were smaller than fire generated particles and are therefore more efficient at scattering light. The optical sensor measured scattered light intensity and the alarm was activated when this intensity exceeded a predetermined value. Problems with all three sensors were described and discussed. The author concludes that the sensors described have the potential to reduce sensor alarm activation due to diesel exhaust in mine air while retaining the capability for early fire detection.
Fire-prevention; Diesel-exhausts; Pyrolysis-products; Safety-engineering; Underground-mining; Underground-miners; Fire-protection-equipment; Safety-equipment; Equipment-design;
Proceedings of the 27th International Conference of Safety in Mines Research Institutes, February 20-22, 1997, New Delhi; Oxford and IBH Publishing Co. Pvt. Ltd., New Delhi, 1997