N.B.F.U. LISTS PRECAUTIONS FOR HANDLING AMMONIUM NITRATE
Suggested Methods of Fire Fighting Also Included in Report
FOURTEEN precautions that should be observed in handling and transporting ammonium nitrate are outlined in a point report on the Texas City disaster recently by the Fire Prevention Bureau of Texas and the National Board of Fire Underwriters.
The report points out that the War Department Ordnance Safety Manual classifies ammonium nitrate as an explosive when it is stored with other combustibles in an explosive area. Smokeless powder regulations apply to ammonium nitrate.
“Proper labelling of containers is of utmost importance,” says the report. “The label should be red in color with the words ‘Hazardous Chemicals’— ‘Ammonium Nitrate’—‘Handle With Care’ prominently displayed with any other notations in small type, preferably of some other color.”
The report points out that ammonium nitrate should never be stored in contact with carbonaceous materials or with cadmium, zinc, copper, tin or lead. It recommends also that it be kept apart from combustible commodities like sulphur, flour, sugar, compressed cotton and charcoal.
The fourteen recommendations of the two fire prevention organizations are:
- Material should be stored only in masonry or fireproof sprinklcred buildings.
- Storage should preferably be in separate fire divisions from highly combustible commodities or well segregated.
- Piles of ammonium nitrate in paper bags in storage should not exceed 10 bags high, six hags wide and 30 bags long with 3 foot separation between piles and handling aisles of 10 feet every 100 feet.
- Spilled material from broken bags must be re-sacked immediately.
- Ship’s holds or boxcars must be thoroughly clean before loading operations are begun.
- Spilled material in the hold, cars or on dock and discarded sacks must be removed immediately.
- Proper dunnage and sweat-boards must he used in ship’s hold and boxcars to prevent friction and to allow for circulating of air.
- Smoking or the use of open lights must be strictly prohibited at any time.
- Other cargo must not be placed in the same hold with ammonium nitrate.
- Keep material clear of all steam lines and wiring.
- Pending the outcome of tests now in progress, it is suggested that steam not be used for fire fighting in compartments containing ammonium nitrate.
- Any ship with ammonium nitrate entering a port must notify the port facility who in turn should notify the chief of the fire department immediately.
- Fire departments combatting ammonium nitrate fires should use only water in large quantities (applied gently so as not to scatter the material) as an extinguishing agent and all personnel entering the fire area must wear masks approved for use in such locations. Fire in ammonium nitrate usually generates large quantities of oxides-ofnitrogen gases which are extremely toxic.
- Cities in which large industrial operations are present or which are in areas subject to hurricanes, earthquakes, tornadoes and other like disturbances should have a well preconceived and organized Disaster Plan to include all relief, law enforcement, fire fighting, military and naval agencies.
The report points out that the Department of Agriculture does not consider ammonium nitrate as explosive when it is stored in wooden containers or paper hags apart from other explosives. Addition of organic substances to prevent caking or cementing may act like a fuse, the report points out, and increase the possibilities of spontaneous combustion. The addition of other substances like super-phosphate and ammonium sulfate may act in the same way.
“Ammonium nitrate usually cannot be detonated by heat or friction,” adds the report, “and it is comparatively insensitive.”
“It may be exploded under favorable conditions by severe mechanical shock or by sufficiently heavy initation of an intermediate explosive agent. Fertilizer piles containing this material should not be blasted. A shock may mechanically set up a chain of events which will result in the detonation of the entire mass of material.”
The explosive factors of ammonium nitrate are affected by temperatures, crystal structure and impurities or extraneous matter. Numerous striking facts are reported in the illustrated 48page printed booklet which is based on the data collected at Texas City by Dr. M. M. Braidech, Director of Research of the National Board, and Engineers Hugh V. Keepers and H. H. Davis of the Texas Bureau.
The. first explosion was so violent that metal drill stems 30 feet long and weighing 2700 pounds were hurled nearly 2 1/2 miles. Plate glass was reported broken 25 miles away. A wave 15 feet high, created by the explosion, surged over the land from the bay.
The loss of property, excluding marine which was not ascertainable, is estimated at $35,000,000 to $40,000,000, including industrial property losses of more than $28,000,000; dwelling houses, $2,000,000; stores and merchandise, $l,000,000; automobiles, $750,000: and city and school property, $1,000,000.