VesselTrax: Sugar Refinery had Explosion Weeks Earlier

An interesting and revealing development in the tragic Imperial Sugar Refinery explosion investigation is that the facility experienced a previous less serious explosion weeks earlier with no injuries.

Selk said no one was injured in that explosion. They do not know all the details about what happened, but he said they were interviewing the company's managers.

Source: wtoc.com via watermon

Yet details from an Associated Press news report mentions that a company spokesman can't recall the details of the earlier explosion at this time.

Steve Behm, a spokesman for Imperial Sugar, said he did not know any details of the earlier dust explosion mentioned by Selk

Source: ap.google.com via watermon

Thats the main problem with these plant explosions that occurring with regularity in the United States. If there are no fatalities or injuries that require hospitalization, then the accident goes unreported to the Occupational and Safety Health Administration officials and the root cause is not investigated until someone is killed or three workers are hospitalized.

In contrast, deployment of the the Chemical Safety and Hazard Investigation Team, an independent federal agency, to an accident scene is carried out according to three main criteria:

Severity of the accident consequences, such as deaths, injuries, environmental impact or property damage

Nature of the facility and materials involved

Potential effects of the accident on members of the public

An update on the cause of the earlier explosion from a company spokesman:

The earlier blast was caused by a small piece of metal that passed through a machine used to grind granulated sugar into finer particles, Behm said. The metal fragment caused a spark that got sucked into a dustcollector and ignited the dust inside it, he said.
The rooftop dust collector had ventilation panels that opened to relieve pressure from the small blast, minimizing the force of the explosion, Behm said. Damage to the dust collector was minimal, and it was quickly repaired, he said.
"The equipment in there functioned correctly and did its job," Behm said.

Source: kaaltv.com via watermon

In addition to explosion ventilation panels there are additional components in protecting a facility from a dust explosions such as infrared heat detectors that can detect temperatures down to 400 degrees centigrade. For example, an extinguished match is 500 degrees centigrade, which astonishingly is all the heat required in ignition for many combustible dusts such as sugar (350-400 C). In the end result, this is the equivalent destructive force of gunpowder in a confined space.

Examples of Combustible Dusts