# Thread: Projection after Dust Explosion

1. Join Date
Aug 03
Posts
1

## Projection after dust explosion

I am looking for a method to calculate distance of projection of concrete or roofing elements, after a dust explosion in a cereals silo.

Could you please give me any adress of people able to inform me, or litterature references.

As you may be know, we are obliged to do such calculation for all the silos, old or new, with capacity over 15.000 m3 (12.000 tons).

Thanks and regards,

2. johnr Guest

## Projection after dust explosion

The principle of calculation is easy.
1 - establish the over-pressure in the vessel as the time of explosion (This takes into account the size of the explosion). Pressure acts perpendicular to the surface. This gives the direction in which lumps will start to fly.
2 - from pressure it is possible to work out the acceleration at the start of the trajectory.
3 - add the effect of gravity and you have a typical ballistic trajectory. Any book dealing with artillery shells will tell you the formula involved
4 - to get a better understanding of explosions refer to books on shock waves, explosions and so on, which are usually found in a military section.
5 - to establish a suitable overpressure is more difficult. You may have to research this in the explosion literature, or try establishing it by bomb calorimeter methods. Also check insurance literature for explosiion hatches, and dust collectors.
6 - to cater for the reduction offects of demolishing the reinforced concrete gets more complicated, because there are so many variables. The essential formula are there, but the data to feed into the formula is often missing, or poorly defined. So to find out how far shrapnel will fly has to be a calculated guess. So develop a guess that makes sense to you. If the authority knows better, they will let you know. If they don't they will have to accept your interpretation as a reasonable engineering guess.
7 - I cannot quote any books or papers because I have been out of the business for about 8 years now.

3. This is not my field, but I wonder if you have tried one of the online literature search engines such as:

http://www.scirus.com

Searching on turned up many papers on the topic. Perhaps these might provide some leads.

4. Join Date
Sep 03
Posts
1
Dear Plantard:

The best people may be in the explosive demolition business; they need to calculate potential trajectories on every job, and are familiar with the strengths of different materials and joint types.

I would refer you to the following:

Controlled Demolition Inc.
Mark Loizeau, President
Phoenix, MD
410 667-6610
410 667-6624 fax
cdi@controlleddemolition.com

Dykon, Inc.
Jim Redyke, President
Tulsa, OK
918 583-9566
918 582-9365 fax
jim@dykon-blasting.com

Best of luck.

Mick

5. ## silo dust explosions

Dear Sir,

Unfortunately I have received your question dated August 03 about silo dust explosions just couple of days ago. Probably you have already solved your problem. Nevertheless I would like to inform you about the new design code for designing silos against dust explosions. It is linked in the German new E-DIN 1055, Part 6 Actions on silos and bins, which is very similar to the European design code EC1 for silos. I was personally involved in preparing that code because my doctoral thesis titled “Dust explosion in silos equipped with pressure relief devices” was dealing with this matter. For civil structures like silos the common VDI 3673 is no more applicable according to DIN-Institution.

If you need any help concerning this matter please do not hesitate to contact me. My e-mail: t.nasr@scherr-klimke.de. By the way our design company has over 35 years in silo design.

Kind regards,

Dr.-Ing. Tarek Nasr
Scherr+Klimke AG
Germany