Forensic Engineers and Consultants

Category Archive: Tips and Advice

One of the Most Amazing Compounds Around – Water?!?!

Around Christmas day of 2022, a mass of very cold air settled in the deep south/southeastern United States (where I live).  It remained below freezing for over 24 hours.  That is very unusual down here.  There was a spate of burst pipes all over the area.  Why?  Water is one of a very few compounds that expands when it freezes…by approximately 9%!!  If a volume of water is sealed off in a section of piping, and that water freezes, it is likely the pipe will rupture. Then, when it warms up again and thaws, liquid water will leave the pipe for an adventure!!

Water expands when it freezes because the water molecules form a six sided crystalline structure in its solid form (remember those six sided snowflakes we all cut out in grade school?).  These large crystals cannot nestle together as closely as individual water molecules. So frozen water needs more elbow room, so to speak.  The other way to state this phenomenon is that ice is less dense than water.  Which is a really good thing for all the fish that live in ponds where it gets cold enough to freeze!  The layer of ice on top of a pond insulates the water beneath it from colder air temperatures.  If that ice sunk to the bottom of the pond instead, the water on top would freeze then sink and eventually the entire pond could freeze and kill the fish in it.

This made me start to think about all the other ways that water is unlike other liquids… and there are quite a few.  They all stem from the fact that water has something called hydrogen bonds or polar bonds between its molecules.  You all know that water has 2 hydrogen atoms and 1 oxygen atom: H2O.  What most folks don’t know is that each hydrogen atom has one electron to donate to a bond and oxygen needs two electrons to fill its orbital shell.  This configuration gives a slightly negative charge to the oxygen end of the molecule, and a slightly positive charge to the hydrogen ends.  These charges act like little magnets and opposites attract!

These bonds give water properties that other compounds of similar molecular weight do not have….  Such as

  • Relatively High Boiling point – Water has a molecular weight of 18 (O=16 , H=1). Ammonia (NH3) has a molecular weight of 17 (N=14, H=1).  All other things being equal, they should have similar properties.  But I’ve already told you that all other things aren’t equal, haven’t I??  Those hydrogen bonds require more energy to pull them away from one another.  That means a higher boiling temperature. Ammonia boils at -28.01°F and water boils at 212°F.  Quite the difference.
  • High Surface Tension – surface tension is defined as “the property of the surface of a liquid that allows it to resist an external force.” Once again, due to the hydrogen bonds, water has the second highest surface tension of any liquid (only elemental Mercury has a higher value). This can be seen in water sheeting off of eaves during a heavy rain, or, back to our fish pond again, water striders doing their thing!

    • Highest Specific Heat Capacity of Any Liquid- This means it takes a lot of energy to raise the temperature of a given volume water and it also means water can dissipate that heat throughout the entire volume easily.  The best visual I’ve seen to explain this is placing a paper cup full of water into a campfire.  As long as water is present, the paper won’t burn.  Here’s a link to a video (you should really watch this!):  https://www.youtube.com/watch?v=fpjLcLa7rkU

This capability is also why water is used in industrial sites for absorbing or transferring heat…there’s literally no better liquid for it.  This ability to absorb heat without changing temperature is why the oceans don’t get as hot or as cold as the land… water takes a long time to heat or cool

Lastly, the volumetric ratio of steam to liquid water is higher than most other liquids….1700:1.  In other words, if I had a 1ft x 1ft x 1ft cube of liquid water (1 cubic foot) that I turned it into steam and kept at atmospheric pressure, that steam would take up 1700 cubic feet of space.  Comparing to ammonia, that ratio is 850.

In the same way that frozen water can rupture pipes, water vaporizing to steam can have devastating effects on systems that aren’t designed for it. If you need an investigation of a loss involving water, in any of its forms, please call our experienced engineering experts at Warren.

As President of The Warren Group, Jennifer Morningstar, B.S.Ch.E, P.E., CFEI, has over 20 years of engineering experience. A licensed professional engineer in several states and a NAFI Certified Fire and Explosion Investigator, she holds a Bachelor of Science Degree in Chemical Engineering from Virginia Polytechnic Institute and State University, as well as a Master of Business Administration from the University of South Carolina. Throughout her engineering career, Jennifer has conducted forensic investigations involving chemical release/exposure, OSHA process safety management, industrial accident investigation, equipment failures, fires & explosions, and scope of damage/cost to repair.  Jennifer is a member of the National Association of Fire Investigators (NAFI), the South Carolina chapter of the International Association of Arson Investigators (SCIAAI), and the American Institute of Chemical Engineers (AIChE).

Know a Fire Sprinkler, Like a Boss – Part 2

Author

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 Read More

Know a Fire Sprinkler, Like a Boss – Part 1

Author

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. Read More

Keeping the Home Fires Burning Without the Fires Burning Homes

Author

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 Read More

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

Author

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. Read More

The Vehicle (EDR)

Author

In a previous blog post, we began to delve a little deeper into the vehicle aspect of the 9-Cell Collision Matrix by taking a look at tires. Let’s now take a closer look at the very diverse and interesting topic of Event Data Recorder (EDR) data. Read More

Scared of Water, or Prefer to Get Drenched? Fire Suppression with Preaction and Deluge Systems

Author

In my two previous blogs, we first discussed wet sprinkler systems (Wet), the most basic and most common fire system type followed by dry sprinkler systems (Dry), which are a bit more complicated.  Ratcheting up another level, in this last edition on sprinkler systems, let’s take a look together at preaction and deluge systems.  These can be complex and variable, so we’ll operate at the 30,000 ft level. Read More

The Vehicle – Tires

Author

In a previous blog post, I gave an overall introduction to the 9-Cell Collision Matrix as an investigative tool used in collision reconstruction. Now let’s focus in a little at each element.

They are called car wrecks, after all…so let’s start with a more comprehensive look at the vehicle component of the matrix.  This review of the vehicle before, during, and after the collision will highlight a few important factors but is not meant to be all-inclusive.  So, let’s get started! Read More

Everybody Has A Part to Play – What’s Your Role?

Across industry and construction sites, there are times when employees of different employers are working side by side, or at least on the same site at the same time.  Some industry examples are when chemical plants have contractors on-site for routine maintenance or during process shutdowns for major overhauls or repairs. OSHA refers to these as multi-employer worksites.  In December of 1999, they revised their citation policy which allows for more than one employer at a worksite to be cited for conditions that violate OSHA standards. Read More

When a DRY Fire Sprinkler System Leaves You Soaked

Author

In my previous blog , I discussed the most basic and most common fire system type: wet sprinkler systems. The possible failure areas discussed with wet systems will also apply to dry sprinkler systems (control valves closed, obstructions, issues in the system, installation, or deficiencies with inspection, testing, and maintenance). Dry systems are even more prone to obstructions than wet systems, so close attention should be paid to that possibility. Read More

Type ofLoss

Not sure what you're looking for?
Browse All

Select Loss Category