Forensic Engineers and Consultants

Archive: Workplace Injuries

What’s Behind That CE Mark Part Three, Machine Guard Requirements

In the first blog in this series, we discussed the story behind the CE mark, the Machinery Directive, and the associated requirements regarding the design, production, and sale of machinery bearing the mark. The second blog discussed a cornerstone of safer machine design, the risk assessment. This installment will discuss another crucial piece of the safety puzzle, machine guard design. Read More

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Ammonia

Ammonia – The Good, The Bad, The Smelly… Part One

Ammonia is a compound consisting of one nitrogen atom and three hydrogen atoms and is denoted by the formula NH3. Its boiling point is -28°F at atmospheric pressure, so unless it is under pressure, it is gaseous at room temperatures. Therefore, pure ammonia is typically stored under pressure in a liquid form. Household ammonia is only 5-10% NH3, the remaining 90-95% is water. Ammonia is extremely soluble in water. It is often depicted  like this: Read More

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

Defective Vertical Baler Causes Serious Crush Injury to Operator’s Arm

I recently worked on an interesting case involving a box baler. An employee of a butcher shop put some empty cardboard boxes in a vertical box baler and pushed the control switch to compact the boxes. After the 30 by 60 inch platen weighing 851 pounds returned to its raised position, the employee reached into the open space above the bottom door on the baler and began to clear cardboard from the bale tie slots in the bottom of the raised platen. Suddenly, and without warning, the steel pin attaching the platen to the raised hydraulic cylinder rod failed. The heavy steel platen fell and crushed his arm which was outstretched over the baler door into the compaction space.

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Reducing Property Damage and Injuries Via Near Miss Reporting

What is a near miss?  It’s an unplanned event that does not result in injury or property damage, but had the potential to do so.  We often call these events “close calls” or “narrow escapes.”  For example, a scaffold guardrail is missing, a worker backs up and as he starts losing his balance, he is able to grab hold of the scaffold buck and prevent the fall.  Other than a racing heartbeat for a few minutes, presumably, no harm, no foul. Read More

Injury Involving Packaging Machinery

From time to time, our forensic engineers here at Warren are asked to evaluate a case involving an injury that has been caused by machinery designed to produce or fill packaging. The hazards associated with packaging machinery are often similar to other commonly-used industrial machinery, but packaging machinery has its own voluntary consensus standard for machine safety. Read More

Injury Involving a Capstan Winch

A capstan winch uses a mechanically powered rotating cylinder, called a capstan, to apply pulling force through a rope. When the rope is looped around the rotating capstan and tightened, friction between the rope and capstan allows the winch to apply force to pull a load. A typical capstan winch is shown in Figure 1 below. Read More

Timber – Falling Beam Strikes Worker

As an experienced safety consultant, I have investigated many serious injuries and deaths at construction sites over the past 39 years. The United States Department of Labor reports that the fatal injury rate for the construction industry is highest of all industries in the nation. Out of 4,386 worker fatalities in private industry in calendar year 2014, 899 or 20.5% were in construction i.e., one in five worker deaths were in construction. Read More

Case Study of an Injury Involving a Soil Mixer

Co-Authored with Aron Olson, P.E.

In May, 2014, a plant farm worker was seriously injured when he fell into the hopper of an electrically powered soil mixer.  The mixer in question used a rotating steel ribbon powered by a 7-1/2 hp electric motor to mix batches of materials such as sand, mulch, wood shavings, fertilizers and other landscaping materials to create potting soil. At the top of the hopper sidewalls, within 6 inches of the ribbon, was a steel grate. Read More

A Case Study in a Coal Mine: What are a Machine Rebuilder’s Responsibilities?

Co-Authored with Aron Olson, P.E.

In November of 2010, a miner was injured by a roof bolting machine (roof bolter) in an Alabama underground coal mine. The roof bolter in question had undergone a complete rebuild intended to return the machine to the original equipment manufacturer’s (OEM’s) specifications. Warren was hired to analyze both the design of the roof bolter and the actions of the rebuilder to determine if either contributed to the unfortunate coal miner’s serious injury. Background information on coal mining and roof bolters, as well as an analysis of the roof bolter and the actions of the rebuilder are included. Read More

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