Purging Natural Draft Furnaces

NFPA 86 (Ovens and Furnaces) and NFPA 87 (Fluid Heaters) recognize that some industrial heating systems are installed where electricity is not available, and heaters must be operated without the benefit of a forced-draft, clean-air purge prior to startup. Nevertheless, natural draft furnaces can be started up safely by ensuring ventilation doors and exhaust ducts … Continue reading Purging Natural Draft Furnaces

Self-Destruct Mode

Many people my age will remember the television show Mission Impossible from the late 1960s. At the very beginning of each episode, the lead character, Jim Phelps (played by actor Peter Graves) and his team of secret agents would receive a new mission from headquarters, and they would have 60 minutes (of TV time) to … Continue reading Self-Destruct Mode

Boiler Purge Causes Explosion

During a recent explosion investigation, this author discovered a new failure mode that is not sufficiently addressed in NFPA’s trio of industrial heating equipment standards (NFPA 85, NFPA 86, and NFPA 87) that cover Boilers, Ovens, and Fluid Heaters, respectively. The failure mode occurs only in heating systems equipped with natural gas burners and flue … Continue reading Boiler Purge Causes Explosion

A Product Safety Dilemma

Some products/activities are inherently dangerous (e.g., cigarette smoking, skydiving) and yet some people enjoy them and pay good money to partake of them. In most cases, the more dangerous the activity, the fewer people choose to engage in it. One notable exception is the hot beverage – a potentially hazardous product that is enjoyed by … Continue reading A Product Safety Dilemma

Restaurant Staff Stays Cool, Causes Fire

Restaurants are relatively frequent victims of accidental fires. Each year, nearly 1 in 100 eating and drinking establishments experiences a fire loss and 57 percent of those fires are caused by cooking equipment (see http://www.nfpa.org/~/media/files/research/nfpa-reports/occupancies/oseating.pdf?la=en). However, the primary factor in determining fire extent and fire damage is often the status of the exhaust system – … Continue reading Restaurant Staff Stays Cool, Causes Fire

Mobile Investigation Workshop

The author of this blog is pleased to announce that a new Mobile Investigation Workshop has been added to the Martin Thermal Engineering collection of tools. The workshop is equipped with many types of hand and power tools for disassembling products and extracting evidence from a fire scene, as well as instruments that are vital … Continue reading Mobile Investigation Workshop

Large Eddy Simulation

Over the past 25 years, the National Institute of Standards and Technology (NIST) has developed, augmented and improved an important computational tool for fire investigators – the Fire Dynamics Simulator (FDS) code. FDS is a flow, heat, and chemistry modeling application that is utilizes Computational Fluid Dynamics (CFD) to model fires and other flows that … Continue reading Large Eddy Simulation

A Spectrum of Hypotheses

Engineering investigators are obliged to utilize the “Scientific Method” when conducting an investigation into a product failure. The basic elements are: Observe, Hypothesize, Test, and Conclude. Occasionally, an investigator will obtain sufficient information from the “Observe” phase, so that only one hypothesis is plausible. In such instances, the “Test” phase is not explicitly necessary, and … Continue reading A Spectrum of Hypotheses

Statistical Inference and Product Failure Analysis

When a consumer product fails thermally, customers may get “steamed” and demand their money back.  When the failures are frequent enough that the Consumer Product Safety Commission receives dozens of complaints about “melted plastic” and “first degree burns” a few weeks after the initial launch of the product, they may require the seller to pull … Continue reading Statistical Inference and Product Failure Analysis

Road Hazards and Vehicle Fires

News reports about fires involving Tesla Motors’ “Model S” electric vehicle have played a role in the company’s recent stock price decline.  However, these fires should be viewed in perspective because they share a common root cause.  Two of the three fires occurred right after the driver accidentally ran over a dangerous road hazard, and … Continue reading Road Hazards and Vehicle Fires