The Triangle, the Quadrilateral, and the Pentagon

One of the tools used to teach people about the danger of fire is the fire triangle. The triangle is used because there are three elements needed for a fire to occur: fuel, oxidizing agent, and an ignition source. The fuel is what burns be it a solid (wood, coal) or a gas (natural gas, gasoline or alcohol vapors). (Liquids don’t actually burn; it is the vapor above the liquid which burns.) The oxidizing agent is typically the oxygen present in the atmosphere. The ignition source can be an open flame, an electric spark, or even a hot surface. Combining these three elements typically results in a fire. If one or two of these elements are taken away, a fire will be extinguished.

In order to have a dust fire, a fourth element is typically required: dispersion. If a dust is in a pile or a layer, it will typically not burn due to the limited amount of oxygen and surface area exposed to the oxygen and ignition source. This statement is generally true and depends upon the flammability of the particular powder that is being exposed to the ignition source. But when the dust or powder is dispersed in the atmosphere, the amount of surface area exposed to the oxidant and the ignition source increase by orders of magnitude. The large amount of surface area of the dust can experience a rapid oxidation reaction and take the form of a flash fire. Technically speaking, this flash fire is a deflagration. If deflagration occurs in an open area the heat and products of combustion are free to expand. This expansion creates a large amount of radiant heat and a pressure wave. But since it is uncontained, the effects are primarily localized to the vicinity of the flash fire.

In order to have a dust explosion, a fifth element is required: containment. When a deflagration occurs within a contained area, the rapid expansion of the heat and products of combustion cannot freely expand. This causes the pressure within the containment structure to rise rapidly. If the pressure rise is sufficient the containment structure will fail violently and rapidly. This failure is the explosion.

It is important to realize that if these five components are present and dust explosion is likely. In order to avoid a dust explosion one or more of these components need to be removed from the area.

In manufacturing plants that create or handle dusts or powders, these five elements are present in various amounts throughout the facility. It is the responsibility of the owner/operator of every facility to carefully consider the processes in their plant and determine how these five elements are to be controlled, both within the process stream and within the building itself. 

Press Release

Dust Explosion: Is Your Facility at Risk?

June 2, 2017

Colorado Springs, CO – Dust explosions occur every year, killing and injuring workers and damaging property. The National Fire Protection Association (NFPA) has issued new standards that apply to all companies that handle potentially combustible dust. Keith D. Robinson, P.E. announces that he will be giving a presentation that will discuss the factors that cause dust explosions and give an overview of the new NFPA standards. The intended audience is Environment Health and Safety (EH&S) personnel and facility managers. However, anyone interested in this topic may attend.

Space is limited. Please call or email to reserve a spot.

Time & Date

July 19, 2017

11 AM

Location

Library 21c: Ent Conference Center

1175 Chapel Hill Drive
Colorado Springs, CO 80920

This event is not endorsed by or affiliated with the Pikes Peak Library District.

Contact

To learn more about this presentation or to reserve your spot, please contact

Keith D. Robinson, P.E.

4966 Daybreak Cir

Colorado Springs, CO 80917

303-746-8904

dust@kdrobinsonpe.com

OSHA and MSHA

In the United States there are two agencies responsible for workplace safety: the Occupational Safety and Health Administration (OSHA) and the Mine Safety and Health Administration (MSHA). These two agencies are part of the US Department of Labor and are under the administration of the Secretary of Labor.  Generally speaking, OSHA is responsible for safety regulations covering general industry and construction while MSHA is responsible for safety covering mining and other mineral based industries. The actual distinction between the jurisdictions of the two organizations are far more complex than my simple definition. If you search for the phrase "OSHA vs. MSHA jurisdiction" you will find a long list of articles about the sometimes not so clear jurisdictional boundaries.

While the two organizations are tasked with similar responsibilities in their respective jurisdictions, they have separate rules and regulations and enforcement procedures. At times these can be remarkably similar and at other times remarkably different. In the gray areas where the lines between the jurisdictions are blurred, operators can be in compliance with the rules of one organization and find itself out of compliance with the rules of the other organization. It is very important that the operator of any facility understand which set of rules govern their operation.

Please remember that I am not an attorney or expert of the law. I am just an engineer that has worked on a fair number of production facilities (both OSHA and MSHA jurisdiction) and interacted with Environmental, Health and Safety (EH&S) personnel whose job is to make sure that the workers are safe AND the applicable regulations are being followed. The things in this blog are not legal or even formal engineering recommendations. If you run into a situation about OSHA/MSHA compliance or procedure, go to a pro. Based on what I have read, you will need a professional who understands the process, the language, and the regulations. If you try to go it alone you risk scuttling your case due to procedural errors even if you have a rock solid, no way to lose case.

Willful Violations = Prison

Over the past few weeks two high profiles cases about business executives or business owners being sentenced to prison for fatal workplace accidents.

The first case comes under the jurisdiction of OSHA and is high profile mainly because it was referenced in a couple of publications/websites dedicated to industrial hygiene and safety. According to montgomerynews.com the owner of a roofing business was sentenced to 10 months in prison after pleading guilty to charges stemming from the death of an employee. The employee died when he fell approximately 45 ft from a scaffold while performing roof repairs on a church. There were several charges resulting from the incident which included four counts of making false statements, one count of obstruction of justice, and one count of willfully violating an Occupational Safety and Health Administration regulation causing death to an employee. (According to OSHA.gov  "A willful violation is defined as a violation in which the employer either knowingly failed to comply with a legal requirement (purposeful disregard) or acted with plain indifference to employee safety."). In this case, the willful violation was due to the owner not supplying fall protection to his employees. The other charges stemmed from false statements made during the subsequent investigation.

The second case has had national and international news coverage. According to the U.S. Department of Justice (justice.gov) Don Blankenship the former Massey Energy CEO was sentenced on April 6, 2016 "...to a year in federal prison and ordered to pay a $250,000 fine." He was sentenced after being found guilty of conspiracy to willfully violate mine health and safety standards. The charges were the results of a catastrophic mine explosion in April 2010 at the Upper Big Branch coal mine that killed 29 miners. The one year sentence is the maximum allowed for that charge.

Blankenship was acquitted of two charges of making false statements that would have carried the chance of much longer sentences. A Massey mine supervisor was sentenced to 21 months in prison for instructing an electrician to disable a methane monitor and another executive was sentenced to 42 months for pleading guilty to charges that he helped evade surprise mine inspections. Blankenship maintains that he did not commit a crime and will appeal the convictions.

GIGO Revisited

Last week I ordered a few small parts from a large, well known supplier. I had been thinking about ordering these for a while but had been putting it off. Then they sent me an email coupon for free shipping and it got me off of the fence and I ordered the parts. The total of the order was around $250. The online catalog indicated that the items "Usually Ship the Same Day". After a few days I hadn't received an email telling me that the order had shipped so I got online to check the status. When I opened my order summary, I was a bit surprised with what I found:

Wow! That is a bit excessive. For that price Scotty should have been beamed the parts to me instantaneously. After a quick phone call to Customer Service the error was fixed and things are back to the way they should be. 

In this case the error was harmless. The company didn't try to charge me $10,000,000 dollars and essentially it was just a typo on a website. But what if this data field were controlling something important?

Way back I wrote about GIGO and blindly trusting the output we get from computers. This glitch illustrates how the computer systems just do what they are told to do by their programmers. If we tell them to do the wrong thing, they will gladly do it, even if it results in disaster. In computer simulations if we put in the wrong boundary conditions, use poor meshing techniques, or even stop the iterations before the solution is converged, we risk basing our designs on flawed data. Any computer simulation must be compared to some benchmark or undergo some sort of "sanity" test. Without these checks, the risk of failures increase dramatically.

Engineering Blog Disclaimer

I need to make sure that every so often I write a disclaimer about the contents of this blog. I am a registered/licensed Professional Engineer in Colorado and several other states (Colorado is my primary state). According to the laws in Colorado (the other states are virtually identical): "Registrants shall at all times recognize that their primary obligation is to protect the safety, health, property, and welfare of the public."

In order to fulfill this obligation, I spend a lot of time performing analysis, simulations, design reviews, etc. for each particular project on which I am working. I am selective on which projects I will assume "Responsible Charge" and subsequently the engineering responsibility. Nothing in this blog should be construed as engineering advice in terms of specific projects or designs. The topics I write about will give general or background information only. Due to space limitations and the goal of a blog, the concepts are necessarily simplified, generalized, and not complete. Because of the general nature of the information, it cannot be blindly used as a design basis or a "how to" manual. For a complete view, consult one of the myriad of textbooks on the subjects I write about or take classes at your local university or college.

Unless it is specifically stated otherwise, I am not in "Responsible Charge" for any project or design that may use the information I have presented as a basis for the design. Anyone reading this blog should use the information I present as a beginning point for their own investigation into a subject matter. If you do want my professional help on a particular project and you want to hire me, please visit my webpage at kdrobinsonpe.com and contact me.

Confined Spaces

You may be asking yourself "What is a confined space?" The official definition contained in the Code of Federal Regulations (29 CFR 1910.146(a)) is:

"Confined space" means a space that: (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 (for example, tanks, vessels, silos, storage bins, hoppers, vaults, and pits are spaces that may have limited means of entry.); and (3) Is not designed for continuous employee occupancy.

Confined spaces are divided into two types: Permit confined spaces and Non-Permit confined spaces. The definitions of these are also given in 29 CFD 1910.146(a):

"Non-permit confined space" means a confined space that does not contain or, with respect to atmospheric hazards, have the potential to contain any hazard capable of causing death or serious physical harm. 

"Permit-required confined space (permit space)" means a confined space that has one or more of the following characteristics: 

(1) Contains or has a potential to contain a hazardous atmosphere; 

(2) Contains a material that has the potential for engulfing an entrant; 

(3) Has an internal configuration such that an entrant could be trapped or asphyxiated by inwardly converging walls or by a floor which slopes downward and tapers to a smaller cross-section; or 

(4) Contains any other recognized serious safety or health hazard. 

Basically, if there are hazards or potential hazards within a room or area that meets the definition of "Confined Space" then it is a Permit Required Space. It is an employers duty to examine their workplace and determine if confined spaces exist and, if they do exist, evaluate each them and determine if they are "Permit" or "Non-Permit" spaces.

If permit spaces exist and the employer decides the employees WILL NOT enter the Permit space, then it is the employers responsibility to:
1. Warn employees of the danger with signs or "equally effective" means. (The employer must tell the employees that the dangers exist.)

2. Take effective measures to prevent employees from entering the permit spaces. (It is not enough to say "Don't go in there".)
3. Reevaluate any confined space if the use or configuration changes. (This is to make sure that a space isn't mistakenly classified as a "Non-Permit" space.)
4. Inform the contractor of the danger and ensure that any contractor employees that enter a space follow a permit program that is in accordance with 29 CFR 1910.

If permit spaces exist and the employer decides that employees will enter the permit spaces, then it is the employer's responsibility to develop AND implement a written Permit Space Plan in accordance to 29 CFR 1910. This plan must be made available for inspection by employees. Without going into any details about a written plan, it basically is a plan that describes;

1. How the hazards will be removed from the space.
2. How the workers will be protected from the hazards that exist within the space.
3, How injured or incapacitated workers will be removed from the space without exposing other workers to risk.
4. What emergency and/or medical equipment will be supplied.
5. Identifies the number of people that must be involved in any entry into a permit space and outlines the responsibilities of each team member.

The specifics of each plan are left to individual employer to develop since each work site is different and has different hazards.

There are a few places around the home that would qualify as confined spaces such as crawl spaces or attics. These two areas are large enough to enter and "do work", they are not designed for continuous occupancy and they typically have limited or restricted means of entry. Generally speaking, most crawl spaces and attics would qualify as "Non-permit confined spaces". I used to live in a house whose furnace was located in the crawl space that had so many Black Widow and Brown Recluse spiders that I think it met condition (4) above and actually should have been a Permit Space! In all seriousness, since the furnace was located in the crawl space, there was potential for a buildup of carbon monoxide (CO) within the space and so it would meet characteristic (1) listed above. If a furnace technician were to enter the crawl space to work on the furnace, it could qualify as a Permit Space and the technician would need to follow a procedure to ensure that the atmosphere was not hazardous and the other elements contained within a Permit Space Entry plan.