NFPA 120-1999 Standard for Coal Preparation Plants

NFPA 120-1999 Standard for Coal Preparation Plants. 2-1.5 Doors in the walls or partitions required by 2-1.4 shall be self-closing. 2-1.6 Drain systems shall be provided in areas where cleaning is accomplished by washing down. 2-1.7 Two remote means of egress shall be provided on each floor of the plant. 2-1.8 Emergency lighting shall be provided at the means of egress stairways in accordance with NFPA 101 ® , Life Safety Code ® , Section 5-9. 2-1.9 Emergency exit signs shall be provided at the means of egress stairways in accordance with NFPA 101, Life Safety Code, Section 5-10. 2-2 Storage. 2-2.1* Coal bins, bunkers, and silos shall meet the following requirements: (a) Storage durations shall be limited to prevent spontaneous combustion. (b) Equipment shall be of noncombustible construction designed to minimize coal hangup. (c) Means shall be provided to remove burning, wet, or smol- dering coal so that it can be disposed of safely. 2-2.2 All interior bins handling dusty material shall be suitably vented in accordance with Section 4-6. 2-2.3 Storage bins for coal shall be located so that sources of heat not intended specifically to control the temperature of coal do not raise the temperature of the coal in the bin, caus- ing spontaneous combustion materially. 2-4.4* Enclosed areas where the failure or malfunction of the ventilation would result in the accumulation of ignitible con- centrations of methane gas shall be designated as Class I, Divi- sion 2 locations in accordance with Article 500 of NFPA 70, National Electrical Code ® . Exception: Areas of a processing plant normally designated as Class I shall be permitted to be considered nonhazardous, provided the follow- ing conditions are met: (a) Ventilation to prevent an accumulation of an explosive or ignitible mixture of gases. (b) Fail-safe continuous methane monitoring designed to sound an alarm when the methane–air mixture reaches 20 percent (1 per- cent methane by volume) of the lower explosive level (LEL). (c) An interlock to stop the process equipment automatically when the methane–air mixture reaches 40 percent (2 percent methane by volume) of the LEL. (d) An electrical system arranged so that when methane concentra- tions reach 40 percent of LEL, all electrical circuits including control circuit conductors are de-energized. (e) Any equipment that is needed to restore the plant to a safe condi- tion, such as lighting, ventilation, or sump pumps, shall be installed in accordance with...