Storage structures
Design considerations
Electrical equipment
Piles or stacks of ammonium nitrate
Ventilation and atmospheric controls
Location of storage areas
Design considerations
In designing ammonium nitrate storage facilities the following points should be considered:
- Buildings over one storey should not be used to store ammonium nitrate;
- Stores must be constructed out of non-combustible materials and be compatible with the ammonium nitrate;
- Buildings must be protected against lightning damage. AS/NZS 1768 - Lightning protection (non-Queensland Government link) can provide guidance on lightning protection;
- Flooring is best made of concrete, should be open and without traps, pits, tunnels, or pockets where molten ammonium nitrate could flow and be confined in the event of a fire;
- If the floor is made of other materials the floor should be protected against impregnation by ammonium nitrate;
- Flooring should have a fall to an open drainage system that will not allow molten ammonium nitrate to become trapped or confined;
- Silos should not be used for ammonium nitrate storage if the material is stored for longer than one week as this material tends to form hard cakes of material which may be difficult to remove safely - this can lead to silo turnover during emptying if there is a hang up on one side of hopper;
- Shelving systems need to be constructed to prevent the build up of the ammonium nitrate or other contaminants on ledges or in corners. The design should allow for easy visual inspection for spillage;
- Liquid also should not be able to accumulate on the shelving;
- Shelving/ storage racks must allow for free passage of personnel;
- Buildings and structures should allow for dry storage of ammonium nitrate by being free of water leakage or seepage through walls, floors or roof.
Electrical equipment
- Electrical wiring and lighting in the store needs to be able to withstand corrosion that may occur in regular fittings. It should have a rating of at least IP65 as per AS 1939 - Degrees of protection provided by enclosures for electrical equipment (IP Code) (non-Queensland Government link) .
- Electrical equipment should be kept where it cannot come into contact with ammonium nitrate.
- Electrical lamps shall be located or guarded so as to prevent hot surfaces coming into contact with bags of ammonium nitrate.
Piles or stacks of ammonium nitrate
- Except where pallet racking systems are used, stacks of ammonium nitrate bags should be limited to 3m in height.
- IBCs (bulk bags) of ammonium nitrate must be stored in stable stacks, preferably less than 3m in height.
- At least 1.2 m free air space must be maintained in between stacks of ammonium nitrate as well as between each stack and the walls of the building.
- You should consult the manufacturer for information on the maximum allowable stack height.
- Other products must not be stored in the same stack with ammonium nitrate.
- Containers of ammonium nitrate must be securely stacked or suitably restrained from falling.
Ventilation and atmospheric controls
- Stores need to be adequately ventilated. This may be provided using either natural or mechanical ventilations systems.
- Inhalation must be kept below any national exposure standard.
- Humidity control may be required as recommended by the manufacturer of the ammonium nitrate.
- The temperature of ammonium nitrate storage should never be permitted to exceed 55°C.
Location of storage areas
The location of ammonium nitrate storage areas needs to be given careful consideration as follows:
- Storage areas need to be kept apart by suitable distance from 'protected places' where members of the public may be placed at risk (e.g. property boundaries, schools, places of worship, colleges, theatres, hospitals, age care facilities). Suitable separation distances are recommended in the table below in (from Table 4.2 of AS 4326 - The storage and handling of oxidizing agents (non-Queensland Government link)) . Under no circumstances must a store of ammonium nitrate be located inside a protected place.
- Storage areas should be located on a floor with immediate access from outside the building.
- All vegetation, combustible materials and non-associated equipment must be kept at least 10m away from ammonium nitrate stores.
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