Report of Explosion at School Bus Yard Was CNG System Rupture


Early Monday morning, the fire department in Napa, Calif., responded to a 911 call reporting an explosion near a compressed natural gas (CNG) school bus at Napa Valley Unified School District's yard in the city. However, the deafening sound was not an explosion, but the high-pressure rupture of an o-ring on one of the CNG system's filters.

‘[The call] came into us as an explosion,’ Napa Fire Department Capt. Carl Johnson told NGT News. As it turned out, though, there was no fire, no one was injured and the bus itself was not damaged.

In fact, when the Napa Fire Department arrived on the scene shortly after the 5:51 a.m. 911 call, one of Napa Valley Unified School District's maintenance technicians was already working on the bus.

Terry Guzman, operations supervisor for the transportation group at Napa Valley Unified School District, told NGT that the vehicle was a mini-bus that has been in service for about 12 years. Every component of the CNG system itself was recently inspected and tested according to guidelines, so the o-ring failure was an isolated incident.

Upon the fire department's arrival, there was a slight odor of gas, Johnson explained. So, the fire department used a fan to clear lingering CNG from inside the bus, as well as used monitoring equipment to check the area for combustible gases in the air.

The environment was deemed safe, and the maintenance technician was able to start the bus without trouble.

‘He started it up, and it ran fine,’ Johnson said.

‘We put the bus back online,’ Guzman remarked.

The Napa Fire Department was on the scene for about 30 minutes, Johnson added.

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