Forensic Engineers and Consultants

Archive: Fires & Explosions

Heating System Losses: Part Two

Previously, Warren posted the first installment of a series on losses associated with heating systems.  The first article looked at central forced air furnaces.  This new article will look at a common form of supplemental or secondary heat, oil filled electric radiant heaters. These heaters are commonly used to provide extra heating in areas that are lacking in central heating capacity. Another rationale for their use arises from manufacturer’s claims that the portable heating units can lower your power bill.  This is based on Read More

Stairs: The Devil’s in the Details

Issues with stairs are interesting with respect to either personal injury, i.e., someone falling on a staircase; or construction defects, i.e., the stairs not meeting Code.  If you’ve ever had to design, build or just “make stairs work”, you can relate to the following sentiment:

“Stairs, Stairs, STAIRS!  I don’t want to discuss them right now!  Let’s talk about something more fun…”.  Whether they be straight-run, scissor, winder, or spiral, interior or exterior means of egress, stairs of all types are simply difficult to deal with, i.e., a PAIN!  However, as you know, if your structure has levels above the ground, Read More

How Long Before the Pipes Freeze?

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An unexpected severe winter freeze will remind many people and businesses that when water in a pipe freezes, the ice will expand and burst the pipe or pipe fitting.  Large losses will result from flooding when the temperatures rise.  Insulation will help, but not prevent freezing.  Insulation simply slows down the rate of heat loss.  The time of exposure to subfreezing temperature is an important factor.

The American Society of Refrigeration and Air Conditioning Engineers (ASHRAE) Handbook of Fundamentals has a short entry on the topic (Chapter 23, page 23.5-6), which gives an equation for estimating the time that it will take an insulated pipe to freeze, Read More

Taking a Practical Approach to Vehicle Fires

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“On average, U.S. fire departments responded to a highway vehicle fire every 182 seconds,” according to the NFPA’s Fire Loss Facts Sheet.

The National Fire Protection Association (NFPA) says that vehicle fires account for about 20 percent of all reported fires. Before I attempt to examine a vehicle fire loss, I like to check various consumer and government agencies websites to see if I can find any recall or historical data that might be important. This is true for heavy truck fires all the way to automobile and motorcycle fires. Read More

T is for Temporary – Issues with Extension Cords and Other Temporary Wiring Applications

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Temporary wiring is just that….temporary, and is typically used for repair and maintenance projects.  In this blog I am going to discuss guidance offered by Article 590 of the National Electric Code (NEC), as well as some points to consider when using temporary wiring, including extension cords and holiday lighting.

Before each use, extension cords need to be inspected for visual damage.  Cords with cuts or splits to the insulation need to be discarded.  Cords with damage to the connectors, including those that feel loose when connected, need to be taken out of service.   Failure to properly select and use extension cords can have a catastrophic result.  Read More

Moisture Intrusion into Structural Reinforced Concrete

Scenario:  The owners of Jones’ Marine, a marina with a wharf structure on a tidal saltwater river, cater to the operators of ships, barges, and large yachts.  There are both diesel and gasoline fuel pumps at the edge of the wharf.  In addition, a large mobile crane for lifting the large vessels out of the water for maintenance is in service at the wharf.  This crane is driven out to the edge of the wharf deck suspended over the water, subjecting this deck and the structure beneath it to very high loading.  They purchased the property from its former owners about 10 years ago and are conscientious about maintenance and upkeep of their thriving facility.  They decide it is time to have a survey performed of the condition of the precast reinforced concrete piles and pile caps beneath and supporting the concrete wharf platform/deck.  They are alarmed at what is discovered by this survey:  Significant spalling Read More

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

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

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

Moisture Intrusion into Concrete Slabs-on-Grade

Scenario:  A young couple is excited about buying their first home.  They pick it out from a catalog of house plans from the developer of a new neighborhood in town.  It will be a brand new construction starter type bungalow home on a slab-on-grade foundation.  For a cost adder, which is considerable to them, they decide to upgrade the finished flooring from carpeting to hardwood laminate.  Unfortunately, after only a few weeks of residency, the hardwood planks begin to buckle and separate from the slab throughout the house.  They do not know what is causing it, or what to do to remedy it, Read More

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

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

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