Explosions In Grain And Oilseed Derivatives Terminals
Last October and last weeks there have occurred 2 big explosions in 2 nearby grain terminals north from Rosario in Argentina.
I can supply some more informations next week, and I am in search of expertise to check possible causes.
Regards,
Pablo Ferres ■
Re: Dust Explosion Experiences
I have worked for 39 years in the plastics industry handling explosive dusts and thus have extensive experience in explosion prevention and protection methods. Have personally seen and investigated several dust explosions. In most cases I have found that they could be avoided if the system was designed correctly using NFPA guidelines.
Regards,
Amrit Agarwal (Tim)
Pneumatic Conveying Consultants ■
Re: Dust Explosion Experiences
For the most part even the best dust containment design will fail if proper maintenance procedures are not implemented and followed with discipline.
Explosions occur because there is an ignition source and fuel of some sort. One has to consider both and have discipline not to take short cuts in order to avoid tragedy.
Many places are designed to recognized guidelines and are timebombs.
Just my two cents opinion.
Antonio Reis
Vitrom Mfg Consultants
www.vitrom.com ■
Re: Dust Explosion Experiences
I agree with Antonio about maintenance, however, it is critical to design the facilities based on "safe mode". What safe mode means is that the facilities are designed assuming the worst case scenario which could be poor maintenance. In this mode the facilities are forced to automatically shut down if the facilities are not operated according to their design.
Regards,
Amrit Agarwal (Tim)
Pneumatic Conveying Consultants
polypcc@aol.com ■
Reply To Antonio And Amrit
Thanks to both of you, we are currently dealing with the aftermath of 2 dust explosions nearby, ( Toepfer's and Arg. Cooperatives Association.) and we are collecting information from NFPA, GEAPS, and other sources to check and eventually correct and improve our cleaning, dust supression sistems, and all eventual spark risks.
Kind Regards,
Pablo Ferres ■
Re: Dust Explosion Experiences
Dear Pablo,
If you don't know the MIE, (Minimum Ignition Energy, in MilliJoules)of the finest dust particles you are handling, the first thing you need is to get this data.
NFPA standards are based on the MIE of sub-200 mesh particles, but if have mostly sub 400 mesh particles you will need the MIE of sub 400 mesh.
I prefer explosion venting to explosion supression because supression hardware is not that reliable unless properly maintained.
I don't think that inerting as a design method to prevent dust explosion would be applicable in your case.
Would be glad to answer any questions that you may have.
Amrit Agarwal (Tim)
Pneumatic Conveying Consultants
polypcc@aol.com ■
Untitled
The latest issue of the NFPA68 is quite helpfull in assisting to design venting against explosions.
The totally reworked edition will be quite clear in assisting those looking for dust explosion venting guidelines and application solutions
Prevention against explosions should always be sought and can be for example done by relatively simple measures like keeping the dust humid during transportation ■
Re: Dust Explosion Experiences
I agree that NFPA68 guidelines should be used for the design of venting systems to protect equipment against internal dust explosions. However, it must be understood that use of NFPA68 does not PREVENT dust explosions, only protects the equipment from catastrophic damage.
In addition there are many details that NFPA68 does not cover. It would be advisable to get advice from experienced specialists for full application of NFPA68 and for the detailed design of the venting system.
Regarding making the dust humid to prevent dust explosions this is a debatable issue. If the dust has a static charge, humid atmosphere in the equipment would be helpful for dissipating the static charge but not otherwise.
Amrit Agarwal (Tim)
Pneumatic Conveying Consultants
polypcc@aol.com, or
pccsolids@aol.com ■
Re: Dust Explosion Experiences
A "perfect" solution is always the result of preventive measures (see NFPA 69) and protective measures. The preventive measures will be focussing on reducing the risk leading to explosions, where as protective measures are aiming at reducing the effects of an explosion.
In any case the blending of preventive and protective measures are to be done with care to avoid creation of a false feeling of safety: personnel could be given the impression that the installation/equipment is safe where as the risk for a devastating event still exists.
Often the investments involved will lead to a conclusion not to protect: this again is to be avoided. If budgets prevent doing the full solution, then it is always best to focus on highest effect measures first then create phased approach to solutions
In any case the advise of expert is recommended to avoid unneccessary or ineffective investments ■
Re: Dust Explosion Experiences
Let me add that the entire design of the process must be done by people who are not only experts in safety but also experts in process design. Both of these functions are critical for safe design and operation of a process. Getting only an "advice" from experts is not sufficient.
Regards,
Amrit Agarwal (Tim)
Pneumatic Conveying Consultants
pccsolids@aol.com ■
Re: Dust Explosion Experiences
Always start with your risk assessment considering :-
The material you are going to handle – is the dust explosive YES or NO. There are no “don’t knows”, if you can’t answer YES or NO get the material tested.
If you can answer NO then consider yourself fortunate!
If the answer is YES, can you change the material so the dust is not explosive? (in real life probably not, but it’s worth asking the question)
The machine you are going to use – is there a source of ignition YES or NO.
This is where the risk analysis is most important. Get advice or use an ‘expert’, but just make sure the ‘expert’ has knowledge of the machine you are intending to use AND of alternative machines.
If the answer is NO then, great.
If the answer is YES, can you change to a machine that will not have a source of ignition? This may well be possible as there are many different machines for materials handling.
If you can’t change the machine, then back to the risk assessment. Analyse the possible sources of ignition, try to design them out completely or minimise the likelihood of ignition occurring.
If you have to accept that despite all your best efforts an explosion may occur, consider what can be done to minimise the effects of the explosion once it has taken place.
Remember, all extras cost money, but these costs are small compared with loss of life and plant destruction.
Finally, NEVER become complacent. Once an explosive dust, always an explosive dust. ■
Dust Explosion
Hello everyone !
We are selling dust collectors in our country. If we have to deal with EX dust, we always build our system conductive, against electrostatic sparks. We use dust disposal systems, to get the dust out of the filter housing as fast as possible. We also use bursting panels, and special safety valves.
Had no explosion yet, that's how it should stay.
I also agree, regular maintance is important, without it, the best designed system is a risk..
bye
Zsolnay Mikls ■
Dust Explosions
Abouth your dust explosion incidents.
Is there any type of data you can access , as you had two explosions the problem can be systemic.
to help you with your investigations and to produce implemetable corrective actions , contact System improvements , or visit the site www. taproot.com
They can offer spanish language problem solving courses. By leading experts in the field . like Arturo de La Garza ex director of safety of CYDSA and CEMEX , Jose Gerard , with 25 years experience in airline maintenance. and many others from the nuclear, oil and food fields. Contact if you can Mark Paradies , he will help you locate the appropiate person with hands on experience in your particular field.
I do reccomend you learn their Root Caise analysis system.
You will be surprised what you will find.
Marco ■
Dust And Explosion Experiences-Dri
A relatively new material since 1969 has come on the market place and usually only dealt with by producers and users unless by surprize by transporters and there have been explosions in manufacturer's plants, user's plants and in transportation vehickles, ships, trucks, railcars and conveyor systems.
The material is called DRI-Direct Reduced Iron made from an extraction process for metals reduction and usually made with reduction materials carbon monoxide and/or hydrogen. The DRI product is pyrophoric and most contains free carbon, unless produced with pure hydrogen.
DRI product will reoxidize at atmospheric conditions and at ambiant temperatures. DRI will also cause flakes of dust to be generated simply by handling it and can produce dust in great percentages if designs are not used to somewhat prevent this dust generation phenomenon. In ocean atmospheres salt content in ambiant conditions will increase reoxidation perhaps 10 fold or more. Friction from air in fast moving vehickles will cause reheat and spark ignition, the same has been seen in dust collection piping. Accumalation in conveyor systems or any area without movement will cause heatup and ignition from the sun or increased atmospheric conditions and self ignite. Ship haulage can cause hold fires and reoxidation of DRI by the slightest amount of seapage of ocean salt water. Any water seapage into a pile of DRI will cause the generation of hydrogen in the accumalated area, bin, ship's hold, storage building, etc. Any small amount of DRI in a pile will reoxidize causing return of the DRI product to its natural state iron oxide. During roxidation, heatup will ensue resulting in fires and possible explosions.
Indicators of possible problems are levels of Oxygen available, levels of dust, levels of moisture, levels of carbon dioxide, carbon monoxide, possible means of heat, friction, spark, electricity, etc.
Some recommedations have been written that indicated piles of a certain height will dissapate the fires during reoxidation. this is true but it doesn't stop it, DRI will continue to reoxidize until it returns to an oxide state and will continue to spread.
Very specific measuring devices should be used or developed for control and monitoring in all handling areas, transportation areas.
Absolute training of anyone handling or dealing with DRI. Certified measures and policies/procedures have to be used by qualified personnel and means of targeting problems.
Any source of Oxygen should never be considered for prevention or control, carbon dioxide, carbon monoxide, seal gases containg them, water for suppression or containment should never be used as it is the source of hydrogen.
Approved suppression materials should be studied and available for use on ships and in building or storage areas, such as purple K, nitrogen. Automatic systems should be designed and local fire companies trained in DRI characteristics. ■
Dust explosion experiences
Often the dust and bulk handling industries are warned for the potential hazards of a dust explosion. Preventive and protective measures are recommended, but little to no evaluations are doen with regards to the actual implementation of such measures, and their potential effects.
I would therefor like to invite those that have had "real" exposure to such events to share their experiences, allowing others to learn. Therefor please advise if you might have had some explosion-like events in installations, what were the observations, was there damage ? Has the cause, or potential cause, of the explosion-like event been determined? Was the installation protected originally by means of explosion prevention or explosion protection measures? How effective were the measures used ? ■