Remains of the broken glassReplacement fireplace shown properly installedExample of the labelsLabels located in this concealed space

 

CASE STUDY

Fireplace Acts Like Improvised Explosive Device

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Challenge

 

The renovation of a century old house included a modern gas-log fireplace normally ignited by activating an electrical switch on the adjacent wall. The owner turned on the switch and knelt to see why the gas had not immediately ignited and received a face full of pellets as the tempered glass door shattered from a gas explosion. The injuries were severe enough to merit a claim against the fireplace manufacturer.

 

 The assignment requested an evaluation of possible design, construction and/or labeling deficiencies that would support a law suit.

 

• Why did the fireplace fail to ignite initially?

• Don’t gas devices have a time delay on flame failure?

• Why was the owner’s face in front of the unit?

• Were there any safety instructions or warnings?

 

 

Process

 

Documents, specifications, photos, and medical and incident reports were reviewed after the site visit. Unexplained ignition delay caused the gas to explode. The investigation then focused on the choice of ignition controller, and instructions and warnings provided by the labels affixed to the fireplace.

 

 National design standards required that the fireplace have a time delay lockout, either separately or internal to the gas control and ignition module, activated upon failure to ignite. This fireplace did not have that required safety function. Further the designer must anticipate all predictable uses and misuses of the device. The labels assumed a rational operator with agility, visual acuity, and some critical analysis skills. The design failed to account for use by the old and infirm, and by normal, capricious or underage children.

 

 Some manufacturers seem to believe that they can solve safety or complex design problems with the liberal application of instruction and warning labels. Often these notices seem to have been written, not by safety professionals, but rather by attorneys, or foreign manufacturers with limited command of the language or the operating conditions of the device or appliance. (In another case, a manufacturer was found liable for an otherwise adequate warning label, just for not testing the effectiveness of that label.)

 

Resolution

Many warning and instruction stickers adorned the “fireplace.” However none were visible during normal operation. Their content indicated that the designer/manufacturer knew of the danger of explosion if the firebox was allowed to fill with unignited gas.

 

 At a nominal additional cost, electromechanical gas controllers are available that will automatically force delay of any possible restart attempt upon ignition failure.

 

 The warning and instruction labels were located in a concealed space below the fireplace, accessible after tilting a grill forward and down. The labels were vague, confusing and impractical, with no external indication of their existence or location. Hanging an instruction booklet on the wall beside the fireplace was impractical. The case settled for the plaintiff because the selection of the gas control valve without a delay timer was a design defect, and the labels inadequately instructed and warned.

 

Epilogue

 

Lets look at the labels to get an idea of what not-to-do when creating instructions and warnings.

 

Click on each image from left to right to see the story unfold

SPECIALTIES

Fire Cause and Origin

Power Wiring and Circuits

Alarms

Controls

Machinery

Vehicles

Grounding

National Electrical Code (NEC)

General Order 95

Troubleshooting

Electrician Trade Practice

Lock Out / Tag Out

 

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