A Practical Guide to Hazardous Area Classification
Miami-FL, Feb 16, 2010- If you are looking for a practical guide to Hazardous Area Classification, then look no further.There is a new ebook in a flip page format (just looks like a real book), that has all the essential information that you need to know about area classification.
As you must have known by now, area classification is very important to industries and facilities that handle, store or otherwise process hazardous (flammable liquids and vapors). Also, if a facility is handling large amounts of dusts (like grain dust or coal dust), then it needs to be classified also as a hazardous area, with the code that is applicable to dusts. This classification can be sometimes very intimidating and even confusing, what with the plethora of varying standards and codes. The IEC system and the North American (NEC) systems are covered for vapors, gases, as well as dusts. Actual real life area classification drawings are provided, that really area a help, as compared to the same stale figures that are repeated in all publications.
This guide is a fast start to your area classification exercise. It is always a good safety practice to review the hazardous area classification of an industrial facility, every few years, due to the changes, modifications in equipment or new layouts that have now become a permanent development in most plants. If the area classification was done ages ago, then it is better to review it once again, to confirm that the old classification still holds, or to change it if necessary.
This guide provides a very concise overview and even provides a step by step procedure that was followed while doing an area classification. Definitely a must have book for understanding area classification.
Also, since a trial version is available, you can download and see for yourself immediately. Click here to get it.
Note that you will require a DNL reader to view it (similar to Adobe reader but much better), you can get it from here.
Why is Acetylene part of Group IIC of IEC (Group A of NEC)
Ever wonder why Acetylene is classified under Group IIC of the IEC’s explosive material classification system (equivalent to Group A of the NEC material classification)? Why is it classified as much more explosive as compared to say, Methane?
Rather than launch into the theory of explosivity and other such things, wouldn’t it be nice to watch how a 0.5 gms qty of Acetylene behaves when ignited? Watch the video below.
More information on the reasons of area classification can be understood by downloading the ebook on hazardous area classification here.
How to classify hazardous areas?
This is the question that many people ask themselves. There are so many standards and practices, so different from each other. You have the Class, Division & Group classification in North America and the Zone and Group system in Europe, Asia and Australia. The NEC also talks about Zones in Article 505 and there is the IEC-Ex harmonization scheme. To make matters more interesting, we have ATEX in the EU.This all adds to the confusion.
On the other hand, all of us agree that a lack of understanding of how to carry out area classification, can result in a disaster at worst, or at best, a huge lifecycle cost. How? If a poor area classification scheme results in a hazardous area marked as non-hazardous, then that is an invitation to a disaster. Similarly, overzealous area classification can result in large swathes of your plant marked as hazardous, when in reality they need not be. If a typical life of a process plant is about 30 years then you have 30 years of increased maintenance and operations costs, that will fly under the radar of most managers. So it will bleed your plant dry without anybody noticing it. Great, isn’t it?
So here’s an answer. Get your copy of the new Practical Guide to Hazardous Area Classification, recently released by Abhisam Software. It costs just $27, but is worth many more times in the value that it offers. In addition to a compilation of all the well known standards and systems of classification, it has practical examples from working process plants including drawings and photos, to give you a unique perspective on Area Classification. And if you do not want to spend even the $27 on it, you can get it free, if you buy the Hazardous Area Instrumentation course from them, but I think it’s only for a limited time.
You can drop your feedback/review of this book in the comments section.
If you would like to know more about how proper hazardous area classification is important, you can refer to a blog post on this blog earlier here.
Anniversary of the Imperial Sugar factory dust explosion-CSB releases a safety video message
On Feb 4th, 2009, on the first anniversary of the dust explosion that took place at the Imperial Sugar factory, the US Chemical Safety Board released a video message. In the video (see below) the CSB chairman John Bresland asks federal regulators and businesses to increase efforts at preventing combustible dust fires and explosions.
For those who remember, the incident was one of the worst dust explosions ever, with 14 fatalities.
Just a few days ago, a coal dust explosion rocked the Oak Creek We Energies power plant. It took place in a silo and injured 6 contract workers. Fortunately there were no fatalities. One of the workers described a loud explosion and a ball of fire came rolling down at them inside the 65 foot high silo, making them scramble to safety, reports the Journal Sentinel of Milwaukee.
What is the cause of so many dust explosions? The CSB completed a major study of such combustible dust hazards and has urged the Occupational Safety and Health Administration (OSHA) to develop a comprehensive regulatory standard designed to prevent dust explosions. OSHA has not issued a standard but has developed a program to increase enforcement of existing regulatory provisions.
One of the causes of these dust explosions is a possible electrical ignition source, due to using non-dust ignitionproof motors, switches and other non-protected electrical and instrument equipment in hazardous areas. Most industry people think of hazardous areas as those that contain flammable solvents and vapors, but fail to remember that hazardous areas also cover dust prone areas. These include grain silos, coal processing and storage plants and yes, even sugar factories. (Under the North American codes, these are classified as Class II hazardous areas and under the IEC codes, these areas are classified as Zone 21 and Zone 22)
Once a dust explosion takes place, it causes severe damage and the only way to safeguard lives and machinery, is by prevention. Use of explosion protected equipment that is certified for use in dust hazardous areas is a must.
(You can learn more about hazardous areas and dust explosion protection in Abhisam Software’s e-learning program on Hazardous Area Instrumentation).
Comments are welcome, as usual.
Explosion and fire at Buncefield Oil Storage Depot - Five companies to face prosecution
It is now almost three years since the Buncefield oil storage depot explosion took place and finally the authorities have declared, that they will be pressing criminal charges against five companies, ostensibly who have been found guilty of acts of omission.
For those of you who do not remember the case, here is a short overview. There were a number of loud explosions ( I mean really really loud-reportedly people in Netherlands and France heard it and it was recorded also a seismic event! ) and a massive fire at the Buncefield Oil Storage Depot in Hemel Hempstead, Hertfordshire, UK. Over 40 people were injured in the accident, fortunately there were no fatalities. Following the explosion, a Major Incident Investigation Board (MIIB) was established by the Health and Safety Commission, supported by the Board of the Environment Agency, UK.
There were a series of investigations and reports being published from time to time by this board and some of the significant findings were as follows -my summary of a rather long series of detailed reports:
a) No consequence analysis was done by any of the design engineers or safety experts, as to what could be the severity of the possible explosions of the flammable vapors generated from the petroleum storage tanks.
b) The level control loop, (that is supposed to control the level in the tank and prevent overfilling) on one of the storage tanks failed. It consisted of a Servo tank gauge connected to a series of valves. This failure led to overfilling and spillage of massive amounts of petroleum into the dikes surrounding the storage tank. Petroleum was being pumped in at a rate of about 550 m3/hr for more than three hours, yet the servo level gauge indication, failed to record any change at all!
However the DCS trend records could be salvaged and the above information was gleaned from them. Apparently the CCTVs were working and the footage showed petroleum overfilling and flowing into the tank dikes, but nobody was watching it at the time.
c) The overfill protection was provided by a point level switch which was supposed to be independently connected to an alarm/annunciator panel (separate circuit from the DCS loop). The panel had an override switch and it may be that the interlock was bypassed (no conclusive evidence since everything got burned in the subsequent fire, this may never be known). However it is warning to design engineers who think that by merely having a redundant level switch is good enough. Were there any common cause failures that both the continuous indication, as well as the interlock failed? Not known for sure.
d) The operators apparently did not notice anything amiss and neither was the control system very sophisticated, to tally the pumping rate into the tank to the rate of change of the level. Now here’s the cake. The pumping rate now increased to 890 m3/hr leading to the petroleum overflowing from the tanks, filling up the bunds and secondary containment areas and forming large vapor clouds. It seemed this occured because the inlet lines were common to all the tanks and the other tanks level indications were working, so the system diverted their inlets into this tank that appeared about half full (due to the faulty level indication). There must have been thousands of gallons of the stuff overflowing from all directions and nobody could notice anything! (Yes, it was about 3:00 am in the morning-but so what- were there no operator rounds of the premises or anything like that?- or it doesn’t happen on the night shifts at all?!)
e) Apparently the hazardous area classification which may have been done during the initial stages, may not have considered wind directions. The entire vapor cloud was carried across the road from the tank farm to an emergency generator building,about 100 meters away, where it is thought to have been ignited. The building apparently was not a classified (hazardous) location.
No doubt this entire catastrophic incident and the consequent investigations will have a major impact on how instruments and controls are designed and maintained in petrochemical/hydrocarbon processing plants, how operator alertness and awareness is important and so on.
More details are available at the Buncefield investigation site.
Note: All images have been sourced from the Buncefield investigation site and all copyrights belong to that site.
