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H2Incidents: Hydrogen Incident Reporting and Lessons Learned

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Definitions

Incident
An incident is an event that results in:
  • a lost-time accident and/or injury to personnel
  • damage to project equipment, facilities or property
  • impact to the public or environment
  • an emergency response or should have resulted in an emergency response.
Near-Miss
A near-miss is an event that, under slightly different circumstances, could have become an incident. Examples include:
  • any unintentional hydrogen release that ignites, or is sufficient to sustain a flame if ignited, and does not fit the definition for an incident
  • any hydrogen release which accumulates above 25% of the lower flammability limits within an enclosed space and does not fit the definition of an incident
Non-Event
A non-event is a situation, occurrence, or other outcome relevant to safety that does not involve a particular incident or near miss. For example, a non-event might consist of a failed safety inspection.
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Incident Report

Battery Room Explosion

Incident Date: 2001

 

Severity:
Incident

Was Hydrogen released?
Yes

Was there Ignition?
Yes

No Ignition Source Defined.

Description

A hydrogen explosion occurred in an Uninterruptible Power Source (UPS) battery room. The explosion blew a 400 ft2 hole in the roof, collapsed numerous walls and ceilings throughout the building, and significantly damaged a large portion of the 50,000 ft2 building. Fortunately the computer/data center was vacant at the time and there were no injuries.

The facility was formerly a large computer/data center with a battery room and emergency generators. The company vacated the building and moved out the computer equipment; however the battery back-up system was left behind. The ventilation for the battery room appeared to be tied into a hydrogen monitoring system. The hydrogen sensor was in alarm upon emergency responders arriving at the scene (post-explosion). 911 callers reporting the explosion also reported hearing an alarm for 3 days prior to the explosion. This appears to have been a local alarm, as it was not relayed at any time to the local fire department. Given how slowly batteries generate H2 (1.3x10-7m/s per amp-cell), it appears as though batteries were charging for a long period of time with no ventilation. Apparently the detector was alarming, and hydrogen continued to build up until it found an ignition source. Due to the damage and actions of emergency responders shutting off all circuit breakers, etc., it could not be verified whether the ventilation system failed, or was previously turned off when the building was vacated. Onsite personnel assumed that the ignition occurred at or near a grounding strap on the battery racks, but in a room full of batteries and electrical equipment, ignition sources are plentiful.

Supporting Documents

Setting

Equipment

Batteries and Related Equipment

Electrical Equipment

Ventilation System

Damage and Injuries

Probable Cause(s)

Contributing Factors

No Characteristics Defined.

The incident was discovered During Operations.

Lessons Learned/Suggestions for Avoidance/Mitigation Steps Taken

The lesson to pass on is that ventilation is critical in UPS battery rooms. Great care should be taken to ensure that the ventilation system is operational, and brings in enough outdoor air to properly ventilate the enclosure.
Electrical safety interlocks should also be considered which would isolate the batteries from its power supply, not allowing the batteries to charge if the ventilation system isn't working properly.

It is imperative that the battery room designers pay close attention to the design of ventilation systems and electrical safety interlocks. There are lots of good (and bad) ways to design and install battery rooms and critical ventilation systems. If designers do not have experience designing UPS battery rooms, experienced consultants should be contacted to ensure a safe and effective design.

In addition, internal management procedures need to be developed which analyze operation of such systems. As in this case, the entire data center was removed and the UPS system was no longer needed. The UPS system should have been decommissioned when the data center was removed. A good management of change procedure would have uncovered this problem before it became an incident.

Date Added to H2Incidents: 1/10/2007