Forensic Engineers and Consultants

Tag Archive: The Warren Group

  1. Know a Fire Sprinkler, Like a Boss – Part 2

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    In Part 1, we looked at the basic parts of a fire sprinkler and took a closer look at other parts including heat responsive elements, wrench bosses, and kick springs. In this part, we’ll look at k-factors and deflectors.

    K-Factor and Orifice Size

    K-factor is a characteristic that relates water pressure to flow rate from the sprinkler, represented as k in the equation Q = k√P, where Q is flow (gpm) and P is pressure (psi).

    If we supply water at 50 psi to a k-factor 5.6 sprinkler, the flow rate is 40 gpm. If we supply 50 psi water to a K25 sprinkler, the flow rate is 177 gpm. There are now sprinklers as large as K33.6, which would flow 238 gpm given 50 psi – big difference from the K5.6!

    The most common k-factors are 5.6, 8.0, 11.2, 14, 16.8, 22.4 and 25.  There are smaller and larger k-factors than these.  For reference, K5.6 and possibly K8.0 are most often found in (more…)

  2. Slippery Painted Exterior Walking Surfaces

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    As an experienced safety consultant, I’m called on to investigate a wide range of premises liability incidents. One common premises liability incident that often results in serious injury is a fall on an improperly painted or maintained walking surface.

    Slip and fall accidents are a common occurrence and can lead to serious injuries and even death. Painted surfaces are one of the most (more…)

  3. The Big Difference Between Conspicuity and Visibility

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    Visibility aids, such as lighting, reflectors, and fluorescent material, are marketed to vulnerable road users (VRUs) like pedestrians and bicyclists as a way to enhance their safety on the road. These visibility aids increase the VRU’s contrast within the roadway environment therefore increasing their visibility. However, increasing visibility does not necessarily mean enhancing conspicuity. For example, the key difference between a visible pedestrian and a conspicuous pedestrian is that a visible pedestrian is distinguishable from their background whereas a conspicuous pedestrian “grabs” the driver’s visual attention. (more…)

  4. The Collision Reconstruction Matrix – The Human

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    Murder, suicide, deceit, and intrigue… car crashes? You bet! In our next installment of the 9-Cell Collision Matrix let us dive a little deeper into the glue that binds all this together, the human element.

    Photo by Mark Turner

    Let’s begin with the most basic human element at the root cause of car wrecks, our old friend inattention. Inattention… a vast word that encompasses many lackadaisical conditions. The daydreaming 16-year-old in math class, the radio knob turner, the back seat talker, the quarter pounder with cheese eater, and perhaps the most offensive, the cell phone user. All very dangerous behind the wheel, and one very dangerous to your future… as it turns out, you will always need good math skills… ask me how I know? Driving is of course a divided attention endeavor, (more…)

  5. Know a Fire Sprinkler, Like a Boss – Part 1

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    In this blog we’ll take a look at the basic and some of the less-known parts of fire sprinklers, with more to come in a later post.

    Here are the basic parts of the fire sprinkler, shown on a pendent glass bulb sprinkler and an upright solder element (“fusible link”) sprinkler:

     

    Let’s take a closer look to learn about some of the less known parts, and also look at two types of sprinklers disassembled. Included in parentheses are some of the different names for some of these parts. (more…)

  6. Keeping the Home Fires Burning Without the Fires Burning Homes

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    As the Holiday Season approaches in the United States, it is a good time to take a look at several ways that the festivities can go awry.

    For people that have cool or cold weather during winter, the thought of a warm, cozy home can be very comforting.  However, many of the things that come to mind can turn the season on its head very quickly.  Candles are a great example of a decorating trend with potentially serious side effects.  The good folks at the National Fire Protection Association (NFPA) tell us that more than one-third of home decoration fires are started by candles, with more than two of every five decoration fires occurring because decorations were placed too close to a heat source.  One fire I responded to as a firefighter occurred because (more…)

  7. The Best Use of Visibility Aids – Contrast

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    There are various visibility aids marketed for vulnerable road users (VRUs). Here, the term VRU is used to describe unprotected road users such as pedestrians and bicyclists. Visibility aids are designed to increase a VRU’s contrast within their environment, making them more distinguishable from the background to a driver. These visibility aids can include both active and passive ways to increase the VRU’s contrast, therefore their visibility. As the name implies, active visibility aids actively transmit light and are powered by a source (i.e., battery powered bicycle headlights and taillights) while passive visibility aids passively reflect light coming from outside sources (i.e., fluorescent, and retroreflective clothing).

    There are a wide variety of active visibility aids to choose from on the market. For example, (more…)

  8. The FORKLIFT 500 – A Need for Speed

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    From a young age, many children are typically drawn to things that are fast.  Fast toys, fast race cars, sports that require speed.  Is it possible that “feeding” this desire tends to make many of us resist, whether consciously or subconsciously, the request or demand to “Slow down!” once we’ve grown up, even when we know that it is the right and wise thing to do?  Now couple this with the natural tendency of most businesses to push for more productivity by doing things faster and more efficiently.  This can be dangerous when we take this combination into a workplace where forklifts are a necessary and integral part of the day-to-day operations.

    Race cars are designed to go fast, and they rely on a properly trained and experienced driver to complete a race successfully and safely.  Forklifts are designed to lift and transport heavy loads, and they also rely on a properly trained and experienced driver to (more…)

  9. GREASE Is The Word…Ensuring Proper Functioning of Wet Chemical Fire Protection Systems in Commercial Cooking Operations

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    Cooking equipment is the leading cause and is responsible for over half of fires in eating and drinking establishments (see Warren expert Chad Jones’ 2020 blog, Structure Fires in Eating and Drinking Establishments, for further reading on fire causes and NFPA 96 on duct inspection and cleaning). Fire extinguishing systems are also routinely provided over GREASE-producing cooking appliances. So why are some of these fires still so bad? GREASE is the word. (more…)

  10. Danger Within Reach

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    How far away from a hazard should you stay?  Your parents or grandparents would probably have told you to stay far away, but what are you to do when a hazard is present, and you must work around or near the hazard?  And what exactly is a hazard?  ISO 12100 Safety of machinery – General principles for design – Risk assessment and risk reduction defines a hazard as a “potential source of harm.”

    Where would a designer of a machine or product start if they wished to protect the user from a known hazard?  Consensus standards are a great place to begin the quest for safety. (more…)

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