False Fire Alarm Sounds at Hydrogen Fueling Station


An audible fire alarm horn sounded on a weekday afternoon at an outdoor hydrogen fueling station. However, no associated alarm signals were received at the fueling station, local host facility, or district dispatch/call center. Host site security personnel placed a telephone call to the district emergency response call center. The horn stopped sounding on its own before first responders arrived. A district fire engine company and a HAZMAT (HMU) company responded within 30 minutes of the phone call. A site survey by first responders found no actual fire, no combustible gas meter activity, or active fire panel alarms. The horn sounded again while responders were on scene, at which point the HMU officer actuated dispenser and remote emergency equipment stops to take the H2 station off line and silence the horn. There was no hydrogen release or fire found.

H2 fueling station equipment providers, host site managers, and district call center personnel subsequently confirmed no automated fire panel alarms or calls registered at the time of the horn soundings. Examination of station fire panel programming and alarm wiring found no errors in programming or damage to the fire horn and its wiring. The root cause of the false horn alarm could not be definitely determined and the horn sounding event could not be replicated.</p><p>In the course of station examination, two other equipment problems were found and rectified. A warning strobe light assembly on an isolated alarm channel was found failed due to water condensation and was replaced with a different strobe with better hermetic design. A combustible gas (CG) sensor head could not be zero calibrated and was replaced. By design, the failed strobe light or the CG sensor should not have caused the horn to sound as the horn and strobe/CG are separate warning/alarm channels.

A full revalidation of the H2 station alarms, fire panels was completed prior to reopening the H2 fueling station. No reoccurrence of false fire alarm horn has occurred in 10 months. First responders requested and received an electronic copy of a site orientation presentation for inclusion on their training site.

  • Safety Systems
  • Alarm Annunciator
Probable Cause: 
Contributing Factors: 
When Incident Discovered: 
Lessons Learned: 

Proactive pre-operational training of host site personnel and first responders helped assure a measured response to this incident. First responders were familiar with location of local alarm panels, emergency stop actuation, and hydrogen storage.

First responders will use site orientation presentation materials in post-incident training.

Keep spare alarm equipment in stock to minimize repair time.

Check hydrogen sensor readings monthly.

Calibrate hydrogen sensors every 3 months.

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