Forensic Engineers and Consultants

Blog Posts by: Jennifer Morningstar

Author Jennifer Morningstar

Expertise Includes:

  • Chemical Release & Exposure
  • Confined Space Entry - Lockout/Tagout
  • Industrial Accident Investigation
  • Environmental Regulatory Compliance
  • Fires & Explosions
  • OSHA Process Safety Management (PSM)

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. It is often depicted  like this:

Ammonia Atom

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.  In fact, ammonia’s affinity for water is so high, that industrial vent streams which might contain ammonia are often bubbled through vessels containing water, and the ammonia in the gas stream will dissolve into the water.

Why is this?  The nitrogen atom is highly electronegative.  It draws the electrons from the hydrogen atom to itself.  Therefore, there is a slightly negative charge around the N and a slightly positive charge around the three H’s. This makes it a polar molecule. Water is also a polar molecule, with a negative charge around the O and a positive charge around its two H’s.  Just like magnets, opposite charges attract each other.  The H’s trying to get as close to either an O or an N as the molecules will allow. These are known as hydrogen bonds.  Since these are both water and ammonia are small molecules, they can get pretty close to each other and form relatively strong hydrogen bonds.

Ammonia and Water

Fun fact: water is much more strongly polar (oxygen is a stronger electronegative atom) than ammonia.  This is why their boiling points are so different ( -28° for NH3 and 212°F for H2O).  It takes that much more energy to break the hydrogen bonds of water…..  Now you know!

Ammonia used in industry has had all the water removed from it and is called anhydrous ammonia.  It is both toxic and flammable; its flammability concentration range is 15 – 28%. Ammonia has a strong distinctive odor that is easily detected by most people in concentrations as low as 20 parts per million (ppm).  This is a good thing because the lethal concentration is 300 ppm, so any leaks, although dangerous, are usually detectable before becoming lethal.

Since the hazards of dealing with anhydrous ammonia are so serious, there are many references and guidelines available to lay out how to safely deal with it:

  • The first place to look would be for any manufacturer’s Safety Data Sheet (SDS). Every SDS has sixteen sections which describe the compound’s physical characteristics, important reactivity considerations, etc.  For example, anhydrous ammonia cannot be used with non-ferrous (e.g. copper) or galvanized metals
  • The Occupational Safety and Health Administration created a standard just for anhydrous ammonia: OSHA 1910.11 – Storage and handling of anhydrous ammonia.  It covers a multitude of aspects from storage vessel labeling to piping & pumping requirements
  • The Environmental Protection Agency (EPA) has published the Accident Prevention And Response Manual For Anhydrous Ammonia Refrigeration System Operators, the title of which is pretty self-explanatory
  • International Institute of Ammonia Refrigeration (IIAR) bulletins
  • National Institute of Occupational Safety and Health (NIOSH) bulletins

In Part Two of this blog series, we’ll look at some of the major industrial uses for ammonia….

As President of The Warren Group, Jennifer Morningstar, PE, CFEI, has over 20 years of engineering experience. Her areas of emphasis include chemical release & exposure, OSHA compliance, boiler systems, industrial accident investigation, fires & explosions, product liability 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 Master of Business Administration from the University of South Carolina.

Distributed Control Systems…Data is the Key

Wouldn’t it be great to have a built-in camera to let you see exactly what went wrong before an incident?  In many manufacturing instances there is, chemical plants especially.  The computer system that operates the plant is called a Distributed Control System (DCS) and it has the capacity to monitor thousands of process variables (flow rates, temperatures, pressures, levels, valve positions, pumps on/off) simultaneously.

Read More

Waste Gas Treatment Equipment Failure: Design & Installation Defects Cause Fire

The thirty-thousand-foot view of manufacturing is raw material in, alter in an appropriate fashion, finished product out, by-product out.  Since the finished product keeps a business in business, it gets the most attention.  What about by-products or waste streams?  Read More

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.  Read More

Not Your Father’s House Fire

Remember the good old days when our homes were built with only lumber, dry-wall, and roofing?   Me neither.  However, we talk about ‘modern’ construction materials like this is a new phenomenon.  The truth is ‘modern’ construction materials started sneaking into homes over fifty years ago.  It’s not only construction materials that have changed: a century ago, we furnished our houses with wood, cloth, metal, and glass. Today, it’s plastics, foams, and coatings.

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OSHA’s Process Safety Management – Is This Process Covered?

In February of 1992, the OSHA Process Safety Management (PSM) standard was issued. The official title is: ‘Process Safety Management of Highly Hazardous Chemicals.’ As its title implies, not every facility is covered by this rigorous standard. A process must contain highly hazardous, as defined by OSHA, chemicals above a certain weight threshold, again defined by OSHA. Notice that this is a process by process determination, so there could be certain processes at a manufacturing facility that are not covered by this standard situated beside other processes that are.
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Boiler Blowdown – It’s Not a Dance Move

When thinking about the safe operation of boilers (and don’t we all?), several systems can readily be named; flame control, fuel/air ratio; steam pressure control, levels in the vessel, etc. What about the water? It seems so passive, as long as there is enough for level control, what’s the big deal? Well, it turns out, that as the steam produced by a boiler is used in the process, the condensate from that steam is returned to the boiler as feedwater. However, since 100% of the condensate is not returned, whatever solids had been in that water before it evaporated to form steam are left in the remaining water.  Fresh feedwater is added to maintain levels, but even fresh water contains some dissolved solids. So over time, the water in the boiler system gets saturated with all sorts of dissolved minerals.
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How a Central Indian Town Changed the United States Code of Federal Regulations

On December 3, 1984, at a pesticide ingredient manufacturing facility owned by Union Carbide, a leak occurred in the Methyl Isocyanate (MIC) plant. Due to the toxic nature of the gases released and the plant’s proximity to local residences, the death toll was in the thousands; both plant workers and nearby residents.  The first recorded public meeting in response to this incident was on December 9th, in Institute, WV, the site of Union Carbide’s only US MIC production unit.  Full disclosure: my father was a research & development chemist for Union Carbide and Institute is about 10 miles down the Kanawha River from my hometown of Charleston, WV. Read More

Permit-Required Confined Spaces – What You Need to Know to Safely Enter (and Exit!)

According to the OSHA regulations, a confined space is anyplace that meets the following criteria:

(1)   Is large enough and so configured that an employee can bodily enter and perform assigned work; and
(2)  Has limited or restricted means for entry or exit; and
(3)  Is not designed for continuous employee occupancy. Read More

Commercial Gas-Fired Cookers Can Do More Than Burn

The first hazard that comes to mind when thinking about large scale ovens and steam kettles is burning or scalding injury. Carbon monoxide poisoning is just as dangerous but less understood, so oftentimes proper prevention methods are not followed. In the United States, this results in over 20,000 emergency room visits and over 400 deaths a year. Before we get to the case study and poisoning prevention methods, we need to know what CO is, where it comes from, and why it is poisonous. Read More

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