Summary
A fire occurred in a battery manufacturing plant that was about to cease operations for the night. The fire caused an estimated $2.4 million in property damage when an electrical source ignited combustible hydrogen vapors.
Background
The incident occurred in the forming room, where wet cell batteries were stored for charging on metal racks. The facility had a wet-pipe sprinkler system, but no automatic hydrogen detection equipment.
Incident Synopsis
At 11:52 pm, a security guard on patrol noticed a free burning fire in the forming room and notified the fire department. It took fire fighters almost three hours to bring the fire under control.
Although the facility was equipped with a wet-pipe sprinkler system, the forming room's branch had been disconnected 10 to 15 years before the incident. A press account said that acidic fumes from plant operations had led to repeated non-fire activations of the sprinklers in this room. The same account quoted a fire official as saying, "If the sprinklers had been working, we would have gone in there, swept some water away, changed a few sprinkler heads, and they'd be back in business."
The incident report doesn't indicate whether the owners ever considered the use of listed, corrosion-resistant sprinklers in this area.
Investigators determined that hydrogen gas, ignited by an electrical arc, was the cause of the fire. The hydrogen was generated by the electrical charging of the estimated 5,000 batteries on racks, and the electrical arc was initiated by the battery charging unit.
Although a functional fire protection system would have helped to extinguish the fire, a properly installed hydrogen detection system, coupled with a properly designed ventilation system, could have prevented the incident altogether.
Hydrogen rises twice as fast as helium, at a speed of 45 mph. Therefore, unless a roof or some other structure contains the rising gas, the laws of physics prevent hydrogen from lingering near its point of production. It is unclear weather the room's ventilation system wasn't functioning properly, or if it wasn't designed properly; but in either case, battery charging facilities need to consult experienced engineering firms on proper location and design of hydrogen detection and exhaust systems. On-site Standard Operating Procedures also need to mandate periodic functional/operational tests.
Adequate ventilation of battery charging facilities is addressed in the Lessons Learned Corner on this website.