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).
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
If there is a human involved in the case, there is a good chance that human factors theories and principles will be applicable. Human factors is the study of people interacting with their surrounding environment. A human factors expert applies their knowledge of human capabilities and limitations to each unique case to assess the physical, sensory, and cognitive factors that caused a person to behave a certain way within the surrounding environment.
Consider the following situations in which a human factors expert would be beneficial: Read More
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
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
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
Machine guards can be compared to the clothes we wear every day. Indeed, they serve a very important purpose. Imagine someone leaving their home on a fine, sunny morning wearing nothing but a smile. Wonder how far they will get through the day before things start going poorly for this individual?
There will be more than a few raised eyebrows and blushes when he stops into the local Starbucks for his usual morning double-dipped and whipped, chocolaty chip with a touch of pumpkin spice cappuccino fix. Good luck with that! Probably going to leave disappointed, empty-handed, and likely wearing handcuffs. This will be the beginning of a very long, very bad day for that individual. Had he recognized the risks associated with this type of behavior, and then put forth a little effort to cover up, he would have prevented many unfavorable and possibly life-changing personal and legal problems from ever occurring!
And so it is with properly guarding a machine. Machine safeguarding helps to protect workers from preventable injuries. Read More
Ladders…not a particularly exciting topic I’ll admit. But hey, we need ladders to help us accomplish all kinds of tasks. Most people have used at least one of the many types of ladders that are available today. And the odds are probably pretty good that many of those users strayed outside the limits of safety a time or two while on a ladder. It is amazing the risks some people will take to save some time or avoid the inconvenience of getting down to move the ladder into a safer position. I wonder how many of those risks would be taken on a ladder if the users knew they were on camera.
Think about astronaut Neil Armstrong. He travelled by rocket almost 239,000 miles through space and Read More
Please join us in welcoming Mechanical Engineer Bob Hickman, P.E., to the WARREN family! Bob has over 30 years of manufacturing and machine design experience in production and quality-driven environments. Bob holds a Bachelor of Science in Mechanical Engineering from Clemson University.
Bob’s Areas of Expertise Include:
-Machine Safeguarding
-Machine Design
-Equipment Failure
-Mechanical Engineering
-Industrial Accident Investigation
-Codes & Standards
-Machinery & Equipment Damage Assessment
-Products Liability Read More
Hazard, risk, and harm are terms that are used in the world of machine safeguarding. How do these words shape the concept of machine safeguarding? Let’s look a little deeper….
Hazard, which Merriam-Webster defines as a noun, lists its first meaning as a source of danger.
1: a source of danger
2a: the effect of unpredictable and unanalyzable forces in determining events : CHANCE, RISK
