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A fire and series of explosions at the Barton Solvents Des Moines, Iowa, on 29 October 2007 was caused by a static electrical spark, according to the US Chemical Safety Board (CSB).

The CSB, in a final report, revealed that the spark resulted from inadequate electrical bonding and grounding during the filling of a portable steel tank.

One employee received minor injuries and one fire-fighter was treated for a heat-related illness in the accident, which occurred at about 13:00.

A large plume of smoke and rocketing barrels and debris triggered an evacuation of the businesses surrounding the facility.

As the CSB case study notes, the main warehouse structure was destroyed and Barton’s business was significantly interrupted.

The accident occurred about three months after an explosion and fire on 17 July 2007 destroyed a Barton Solvents facility in Wichita, Kansas.

The CSB attributed that accident to static sparks and lack of bonding and grounding as well in a June 2008 final report.

John Bresland, chairman and chief executive officer of the CSB, said: ‘These accidents show the need for companies to address the hazards associated with static electricity and flammable liquid transfer.

‘They should apply good practice guidelines – outlined in our case study – to determine if facilities are properly designed and safety operated.’ The accident in Des Moines occurred in the packaging area of the facility as an operator was filling the 300-gallon steel tank, known as a tote, with ethyl acetate, a flammable solvent.

The operator had secured the fill nozzle with a steel weight and had just walked across the room when he heard a ‘popping’ sound and turned to see the tote engulfed in flames.

Employees tried unsuccessfully to extinguish the fire with a handheld fire extinguisher before evacuating.

Randy McClure, lead investigator at the CSB, said: ‘The CSB investigation found the nozzle and hose were not intended for use in transferring flammable liquids.

‘Furthermore, we found the steel parts of the plastic fill nozzle and hose assembly were not bonded and grounded.

‘Static electricity likely accumulated on these parts and sparked to the stainless steel tote body, igniting the vapour that accumulated around the opening of the tote during filling.’ The report noted that static electricity is generated as liquid flows through pipes, valves, and filters during transfer operations.

Metal parts and equipment must be electrically wired to each other, known as bonding, and then electrically connected to the earth, known as grounding.

McClure added: ‘In this case, all the conductive metal objects in the nozzle and hose, and the steel weight that was suspended from the handle by a wire, were all isolated from ground and were susceptible to static accumulation and discharge.

‘This is a setup for disaster.’ The packaging area – where the fire started – had no automatic sprinkler system and was adjoined to the flammable storage warehouse.

The investigation found the wall separating the two areas was not fire-rated.

As a result, the warehouse was rapidly consumed, and although this area had an automatic sprinkler system, it was incapable of extinguishing the large blaze.

The case study lists several key lessons for safe handling and storage of flammables.

Bresland said: ‘We would hope every operator of similar liquid transfer facilities downloads and studies this report and the earlier Barton Solvents Wichita report to avoid a repetition of these accidents.’ Facilities are urged to ensure that equipment used to transfer liquids is properly bonded and grounded; fire suppression systems should be installed in packaging areas; and packaging to be used for flammable liquids – such as the portable steel tanks – should be separated from bulk storage areas by fire-rated walls and doors.

The CSB investigation determined that if Barton had implemented a comprehensive static electricity and flammable liquid safety program, in compliance with current regulatory standards and good practice guidelines, the fire likely would have been prevented.

These include the OSHA Flammable and Combustible Liquids standard and codes and recommended practices of the National Fire Protection Association.

US Chemical Safety Board

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