Forensic Engineers and Consultants

Archive: Fires & Explosions

Conveyor Backstops: Sometimes One Isn’t Enough, Part 2

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This is the second in a two-part blog series about conveying equipment that severely injured a worker at a mine. In case you missed it, click here to read Part 1 where I describe the incident and the mining equipment. In this part, I will discuss my engineering analysis of the incident and the machinery involved and share the conclusions I reached.

The injured miner was a front-end loader operator. He was not a maintenance worker. He simply responded to a radio request for help with the conveyor. Power to the electric conveyor motors was locked out, but none of the maintenance workers did anything to lock out or block the hazardous gravitational potential energy in the heavy load of stone on the belt. Read More

Conveyor Backstops: Sometimes One Isn’t Enough, Part 1

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This is the first of a two-part blog series describing an incident involving conveying machinery that seriously injured a miner. Part 1 describes the machinery and the incident. In Part 2 I will summarize my engineering analysis of the incident and share the conclusions I reached.

A loaded, inclined conveyor belt may contain hazardous levels of energy due to gravity. To protect workers, anti-reverse devices called backstops are installed on inclined conveyors to prevent unexpected downhill movement. The Conveyor Equipment Manufacturer’s Association (CEMA) defines a backstop as: Read More

Spontaneous Combustion…Is it hot in here or is it just me???

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In the old-timey Fire Triangle, you have heat, fuel, and oxygen.  Get these three together in the right quantities, and you get fire.  What if the fuel provides its own heat?  That’s spontaneous combustion, or spontaneous ignition.  NFPA921 defines this as “initiation of combustion of a material by an internal chemical or biological reaction that has produced sufficient heat to ignite the material.” Read More

Heavy Machinery Fires Caused by Hydraulic Hose Failures

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Heavy machinery fires are often caused by hydraulic hose failures.  Pressurized hydraulic fluid escaping from a failed hose assembly can be atomized into a fine spray that can be ignited by heated engine surfaces such as the engine exhaust or turbocharger.

Hydraulic hoses near the engine compartment of an excavator that burned.

 

Hydraulic hoses often fail due to age and wear, requiring regular inspection and replacement of hydraulic hoses to prevent failures. Hoses may also fail if they are misrouted.  Misrouting can lead to the hose being pinched or causing it to chafe against a sharp metal surface. Read More

Interpreting Industrial Incident Data – Lesson Learned

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This is a case study about an incident I investigated involving a major upset in a distillation column.  This blog builds on the previous blogs about the Distributed Control System, DCS – Data is the Key.

Distillation is a method of separating mixtures of compounds with differing boiling points.  Uncle Bill with his still on the hill separates ethanol, that boils at 173°F, from water that boils at 212°F.  If the mixture is heated to above 173°F, but below 212°F, the ethanol will boil, the vapor will travel up out of the unit and then can be condensed and served over ice with an olive…   Any mixture of two or more chemicals with different boiling points can be separated in this way.  The distillation Read More

TVSS or SPD … Can I Buy a Vowel? Understanding Surge Protection and the Changing Requirements

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Surge Protective Devices (SPD), formerly known as Transient Voltage Surge Suppressors (TVSS) have been around for a long time.   The most recognized version is integrated into outlet strips and used to protect sensitive electronics from surges, or higher than expected voltages on the power line.  Early versions of these surge strips were known to have problems where internal components could overheat and cause a fire.  Thermal protection was added to the designs to greatly reduce the potential for a fire hazard.  Such an implementation in an outlet strip is considered a Type 3 SPD. Read More

The Condensate System – An Important Item in Routine HVAC Maintenance

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HVAC systems are almost everywhere in the United States now.  As a life-long resident of the humid south that grew up in a home without central air conditioning; I definitely appreciate the ability of a well-designed and maintained HVAC system to remove the oppressive summer humidity.

The very humidity that makes your clothes damp with sweat and hastened the invention of cooled leather seats in automobiles also has another route to create havoc…condensate.

In order for an HVAC or “air-conditioning system” to reduce the humidity in the air of your home or office it must first cool the air down to a point where the air can no longer keep the moisture in suspension as water vapor.  The moisture must condense… creating condensate.  This is what is happening when your cool beverage of choice “sweats” on the exterior of the container in the humid summer. Now that you have liquid water, as opposed to water vapor, this condensate must be directed out of your conditioned space to prevent water damage due to backed up or leaking condensate. Read More

What Does a Recovery Boiler Recover? – Quite a bit, actually!

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The Kraft paper process was invented in 1879 and produces a stronger finished product that other paper manufacturing methods. One of the waste streams is known as black liquor and is a mixture of solids and water.  It contains lignin, hemicelluloses and chemicals used in the pulping process. The original process had no use for this harmful waste stream and it was dumped into nearby waterways, to their detriment!!!  Mr. G.H. Tomlinson invented the recovery boiler in the early 1930’s.  This development made the Kraft process the manufacturing method of choice, as explained below. Read More

In a Flash – The Transfer of Energies in Our Global Electrical System

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According to published weather data for the year 2019, 2.35 billion lightning strikes were recorded across the world, with 223 million of these in the United States.  The movement of atmosphere causes electrical charges to build up between clouds.  A tipping point is reached where the insulating properties of the air cannot withstand the level of energy and a discharge occurs.

Image Credit: Charleston Post and Courier. A lightning strike over Charleston, SC on July 3, 2019.

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Congratulations Tom Kelly on CESCP Certification!

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Congratulations to Tom Kelly for completing his Certified Electrical Safety Compliance Professional designation. The National Fire Protection Agency (NFPA) program, CESCP, is designed to meet the needs of electrical and safety professionals who oversee electrical safety programs or who manage electricians and other personnel exposed to electrical hazards.

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