Explosion Relief Requirements for Industrial Ovens
June 16, 2010
By: Steve Onsager
The design of industrial ovens is dictated by two primary standards:
- National Fire Prevention Association Standard NFPA-86 Ovens and Furnaces
- Factory Mutual Property Loss Prevention Data Sheet 6-9 Industrial Ovens and Furnaces
The redundant safety systems and construction methods required by these standards have three primary safety goals:
1. Safeguards Against Fire.
Fire prevention in ovens requires good design, maintenance and care not to exceed safe operating temperatures. Fire protection or control is largely a matter of providing automatic sprinklers or other types of fixed fire extinguishing systems. Any oven that has sufficient combustible material in its contents to sustain a fire needs automatic sprinkler protection. Exhaust ducts that will contain combustible deposits also need sprinklers. Sprinkler heads should be rated at 50°F to 100°F above the maximum operating temperature of the oven.
2. Preventing Fuel Explosions.
Basic safeguards for oven burner systems include (a) a reliable ignition source before fuel can reach the main burner, (b) a limited trial-for-ignition of the main burner flame, and (c) shutoff of fuel on flame failure. Burner flame outage is the ultimate result of undesirable conditions in the ventilation, circulation, fuel-air supply or ignition equipment. The proper combination of interlocks and flame-supervisory combustion safeguards are essential. Supervision of fuel pressure, airflows, and purging is important for anticipating the development of unsafe conditions and initiating a safety shutdown. This supervision gives further protection by preventing improper sequences of operation that could result in a hazardous condition.