Forensic Engineers and Consultants

Archive: Consumer Products

Stop or I’ll Soot!!!

Fire. Something about fire touches our brainstems…both good and bad!  Uncontrolled fire is terrifying and deadly to be sure.  But the controlled burning of wood at a campfire or in a fireplace in your home almost can’t be beat, to my mind! For that very reason, a fairly common amenity to houses nowadays is the gas log fireplace insert.

When not installed properly, these logs will generate soot. These soot particles can leave the fireplace and meander.  All. Over. Your. House.  Literally, if enough soot gets into the HVAC system, you can have soot in every room.  If the logs soot badly, you will notice right away and correct the problem.  It’s when the logs produce lesser amounts of soot that it will build up so slowly as to not be noticeable.  That is, until you adjust a picture frame and notice how dingy the wall has become.

It can cost tens of thousands of dollars to clean soot from a home.  Soot removal is a specialized restoration service that a typical homeowner cannot provide for themselves. Where there is soot, there is also carbon monoxide which can cause a host of physical ailments, as well. Prolonged exposure to soot can unleash a host of breathing problems, including asthma, bronchitis, and respiratory infections.

Fire Place with Gas LogsFigure 1: Properly aligned logs in a gas burning fireplace allow for a much better ambiance.

Why does this happen? Remember that combustion is a chemical reaction at its roots.  The clean, or complete, combustion you want in a furnace or stove results in that quintessential ‘blue’ flame. And in those applications, that is exactly the desired result; maximum efficiency and heat for heat transfer.  However, if the fuel-to-air ratio is modified, you can bring some yellow to the party and have a gas flame appear more like the flames generated by a wood fire. Still, the yellow Bunsen burner doesn’t draw you to sit down to bask in its output, does it?

Bunsen Burner

Figure 2.  Different fuel-to-air ratios dictate flame color in a decidedly unromantic Bunsen burner

Hence the gas log fireplace insert.  At the heart of it, a typical gas log fireplace insert is a burner that has the proper fuel-to-air ratio for either natural gas or propane to produce the yellow flame similar to a wood fire.  They also have ceramic ‘logs’ that are placed around the burner to further mimic the look of said wood fire.

The proper placement of the faux logs is critical to the safe operation of the fireplace, however.  From the front, the logs give the appearance of a stack of wood.  If you inspect the set from the top, however, the area around and above the burners is free from objects.  If the logs are not properly placed or get knocked out of place and get in the way of the flame from the burner, then impingement occurs.  The flame impinging on the ceramic log will cause soot to form.

Soot on a ceramic log placed improperly - WarrenFigure 3:  Soot on a ceramic log that was placed improperly. This condition can cause soot to spread throughout the house.

Therefore, when installing a gas fireplace insert follow the log placement instructions carefully!  If there is no glass in between the logs and whatever room they are in, it’s also not a bad idea to check the log placement when doing annual maintenance on your fireplace insert.

Jennifer Morningstar, PE, CFEI, has 19 years of industrial experience. Her areas of emphasis include chemical release & exposure, OSHA process safety management, industrial accident investigation, fires & explosions, and scope of damage/cost to repair analyses. She spent 16 years working at a polyethylene terephthalate (PET) manufacturer.  She is an OSHA-trained Process Hazard Analysis study leader and completed Root Cause Failure Analysis training to become an Incident Investigator. Jennifer authored procedures for lockout/tagout and confined space entry. She has experience as an energy management consultant in a variety of industries including mineral extraction, pulp & paper, animal harvesting & packaging (including rendering) and grain milling.  Jennifer holds a Bachelor of Science Degree in Chemical Engineering from Virginia Polytechnic Institute and State University as well as a Masters of Business Administration from the University of South Carolina.

Unguarded Shear point 1 white

Unguarded Shear Point on Force Tester Amputates Worker’s Finger

A worker was injured while testing gas springs similar to the type that hold the hatchback of an SUV open. The hazard that injured the worker was an unguarded shear point. The tester contained a mounting plate that was raised and lowered by a pneumatic cylinder.

The pneumatic cylinder lowered the mounting plate while the worker’s fingers were in the hazardous, unguarded shear point. Read More

Electric Hazard Guardrail photo

Hazards Can Lurk Anywhere … Watch Your Step …

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While on a lunch stop during a recent vacation trip through Tennessee, I happened across a safety hazard that required immediate attention.  The establishment had a raised concrete patio at the front with a steel railing around the perimeter.  At one edge of the patio was a set of stairs with a continuation of the steel railing used as a handrail.  The top edge of the patio had light strings wrapping the top metal bar as accent lighting for the perimeter.  The light string continued down the stair handrail wrapped in the same manner as the rest of the patio. Read More

Hot Tub Hazards

Danger Lurking in the Hot Tub

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Several dangers involving the use of a hot tub (spa) may readily come to mind, such as the risk of shock or electrocution, or the risk of drowning for unsupervised young children.  Not so readily apparent is the effect of overheating the human body, or “hyperthermia”.

Some individuals are more susceptible to the effects of hyperthermia, including the elderly, young children, and those in poor health.  The effects of hyperthermia, or overheating of the human body, cause direct responses such as headache, nausea, heat exhaustion, increased cardiac output, lethargy, confusion, heat stroke and unconsciousness.  The onset of hyperthermia is defined as being at 99.5° F; if the body temperature reaches 104° F, a life-threatening medical emergency exists.  Read More

Figure 2: A Webshare photograph from a scan captured from the safety of a balcony in the workshop. The scanner operator never had to climb directly above the forklift to create the shot in Figure 1. The Webshare user can pan, zoom, and measure from the photograph. The grey target icons represent other scan locations on the ground.

Another Dimension of Engineering, Part 2: Visual Demonstrations Can Clarify the Issue

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In our last post on 3D scanning, we introduced Warren’s new Faro Focus X 330 three dimensional scanner.  To recap, the Faro scanner combines three dimensional laser measurement with automated photography to capture 360-degree data from the real world. Potential applications include vehicle accident scenes and damaged vehicles, structural collapses, fire scenes, flood damage scenes, and machinery and equipment analysis, among others. In this post, we will highlight some of the outputs that can be created from the detailed data captured by the scanner. Read More

A power buggy fitted with an outrigger for tip-over testing.

Injury on Power Buggy

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When an operator is thrown from a ride-on vehicle when it tips over, such as a mud buggy, serious injury or death can result. In one such case I investigated, the issue centered on the maintenance of the vehicle, specifically whether a maladjusted hydrostatic drive caused the braking mechanism to malfunction. Read More

One of the fractured Grade 5 bolts used to secure a concrete truck mixer drum to a drive flange.

Bolted Connection Failures

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One of the most common features of machinery, consumer products, and assemblies of any type is the bolted joint. Sometimes the joint fails, with results ranging from inconsequential to catastrophic. The design of a joint is in the purview of an engineer, who must consider the material to be joined, the geometry of the joint, the loads imposed on the joint, the strength of the connectors (i.e., bolts, screws) environmental effects (i.e., temperatures, corrosion) and perhaps other factors. Read More

A view of the primary air inlet on one brand of firelog.

Firelog Maintenance: Tips to Keep Your Home Soot Free

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If you have ever experienced it, you know that sooting from a fireplace can cause unsightly damage throughout a home. In some cases, sooting from gas firelogs is caused by improper placement of the logs, such that flame impinges on the artificial log. When heated, the “log” will give off soot, so placement of the logs is important. Some manufacturers provide locating pins for the logs to rest on, so that proper placement is easier to achieve. Read More

Frozen Tankless Water Heater Losses

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Recently, we have seen a number of water damage losses stemming from gas-fired and electric tankless water heaters exposed to freezing temperatures. Tankless hot water heaters have been growing in popularity and use due to their energy savings over traditional water heaters. These units are typically installed on the exterior of a home or business in areas of the country where prolonged freezing or extremely low temperatures are not common. Read More

A view of a pipe elbow that cracked after being exposed to sub-freezing conditions.

Freeze Damage to Fire Sprinkler Systems

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The ongoing frigid temperatures serve as a reminder of the many investigations by Warren engineers involving fire sprinkler systems that have failed when some part of the system was exposed to the sub-freezing conditions. Interestingly, failures do not necessarily occur within the area of greatest freeze exposure, as the failure mechanism is the extreme pressure that results from the growth of an ice plug inside the exposed pipe in which the high pressure will rupture the weakest component which may even be located in a heated area of the sprinkler system. Read More

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