Hazards Associated with the Handling, Use and Storage of Ammonium Nitrate
Hazards Associated with the Handling, Use and Storage of Ammonium Nitrate
June 6, 2013
On April 17, 2013, an ammonium nitrate triggered explosion occurred at a West Fertilizer Company plant in West, Texas, just north of Waco. This tragic incident killed fourteen people and injured about 200 others. Among the deceased were ten emergency responders from local fire departments and emergency medical services.
Although details of the incident are limited at this time, it is important that members of the fire service be proactive and familiarize themselves with the fire and explosion hazards associated with the use, handling, storage and transportation of ammonium nitrate. Ammonium nitrate, a solid, and anhydrous ammonia, a gas, are used as fertilizers in the farming industry. It is also important that fire departments evaluate the potential risks of an incident, such as the one that happened in Texas, occurring in their respective jurisdiction and the consequential impact on fire department activities. Now is an opportune time to undertake such an evaluation, when the growing season has just begun and when transporting, using and storing ammonium nitrate fertilizers are frequent activities.
The Ontario Fire Code deals with indoor storage of ammonium nitrate in Subsection 3.3.3. of Division B. These provisions, however, do not apply to blasting agents or fertilizer storage on railways regulated by Transport Canada.
Subsection 3.3.3. of Division B covers a number of fire safety matters, including the size and construction of storage buildings, their placement relative to property lines, the type of adjacent occupancies permitted, fire protection features (e.g., sprinkler protection is required for storage buildings, except as otherwise approved), control of ignition sources, special handling procedures related to spills, and use of explosives.
In addition, Section 5.6 of Division B deals with the storage of compressed gas cylinders indoors and outdoors. These provisions apply to compressed anhydrous ammonia.
Combustible dust-producing processes associated with the production of fertilizer products would be subject to the provisions of Section 5.10 of Division B.
Fire safety plans as described in Section 2.8 of Division B are required for high hazard industrial occupancies (Group F, Division 1) where the occupant load exceeds 25 persons and medium hazard industrial occupancies (Group F, Division 2) where the occupant load exceeds 100 persons.
Ammonium nitrate is used outside the farming industry, in many other fields: explosives in mining, road construction and demolition; pyrotechnics; military applications; medicine; and various uses in laboratories. Other agencies and jurisdictions regulate the sale, distribution and use of products containing ammonium nitrate. For example, Transport Canada has requirements for the rail distribution of ammonium nitrate and Natural Resources Canada has requirements for the selling of ammonium nitrate (28 to 35% nitrogen content).
The Office of the Fire Marshal (OFM) is monitoring the investigation of the Texas explosion through media reports and contact with its state counterpart.
The attached questions and answers document provides additional information about ammonium nitrate and associated hazards. In addition, the table below gives contact information for staff members who can respond to enquiries on ammonium nitrate and related topics:
OFM Staff Members
Fire Code requirements
Yosh Imahori, Fire Protection Engineer
Inspections and Fire Code enforcement
Manager of the OFM’s Community Safety Enhancements Unit
Local OFM fire protection adviser
Fire ground strategies and tactics
Academic Manager, Ontario Fire College
Hazards Associated with the Handling, Use and Storage of Ammonium Nitrate: Questions and Answers
- The fertilizer plant in West, Texas, contained anhydrous ammonia and ammonium nitrate. What are these chemicals?
Ammonium nitrate (NH4NO3), which contains 35 percent nitrogen, is a white crystalline solid at room temperature and standard pressure. It is commonly used in agriculture as a high-nitrogen fertilizer and it has also been used as an oxidizing agent in explosives, including improvised explosive devices.
Anhydrous ammonia (NH3), which contains 82 percent nitrogen, is the most concentrated nitrogen fertilizer, and is an efficient and widely used source of nitrogen fertilizer. It is applied by injecting it into the subsoil, where it combines with the soil’s moisture to provide the essential nitrogen nutrient. It is stored under pressure (as a liquid) and is stable under normal conditions of storage and handling.
- What are the fire safety concerns associated with ammonium nitrate (AN)?
AN is an oxidizing material that, at elevated temperatures, will support the combustion of materials such as wood, paper, fuel oil and sulphur.
AN undergoes thermal decomposition when heated to temperatures above about 150°F and, under certain conditions, this decomposition may become dangerous. Because AN is usually stored in very large quantities, it has the potential to escalate an ordinary fire into an incident approaching disaster proportions.
When the decomposition gases are sufficiently confined, they will accelerate or otherwise support the decomposition reaction.
Two of the decomposition gases, nitrous oxide and ammonia, when mixed with certain other gases such as carbon monoxide, are capable of exploding. Such explosions may be of sufficient power to detonate the stored AN.
- How is ammonium nitrate regulated by the Ontario Fire Code?
The Ontario Fire Code deals with indoor storage of ammonium nitrate in Subsection 3.3.3. of Division B, which applies “to the storage of ammonium nitrate in quantities exceeding 1000 kg in the form of crystals, flakes, grains or prills, including fertilizer grade or other mixtures containing 60% or more ammonium nitrate by weight, but does not apply to blasting agents or fertilizer storage on railways regulated by the Canadian Transport Commission.” This quantity would be about 40 25-kg bags, where there is a 21% nitrogen content from ammonium nitrate (not all fertilizers use AN for their nitrogen source).
Subsection 3.3.3. of Division B outlines requirements relating to size and construction of storage buildings, their placement relative to property lines, the type of adjacent occupancies permitted, fire protection features (sprinkler protection is required for storage buildings), control of ignition sources and handling procedures.
In addition, Section 5.6 deals with the storage of compressed gas cylinders indoors and outdoors. These provisions apply to compressed anhydrous ammonia.
Combustible dust producing processes associated with the production of fertilizer products are subject to the provisions of Section 5.10 of Division B.
Fire safety plans as described in Section 2.8 of Division B are required for high hazard industrial occupancies (Group F, Division 1) where the occupant load exceeds 25 person and medium hazard industrial occupancies (Group F, Division 2) where the occupant load exceeds 100 persons.
- Where is ammonium nitrate fertilizer found in Ontario?
AN sites are located throughout the province. The vast majority of AN users in Ontario are not identified in any formalized registry, so a comprehensive list of locations does not exist. However, in the absence of a single comprehensive list, a partial list can be compiled with information obtained from the Ontario Agri-Business Association Web site, www.oaba.on.ca, and industry or agri-business directories.
- Are all fertilizers hazardous?
It is important to note that not all fertilizers contain AN. Household fertilizers typically do not contain AN.
Mixed fertilizers containing not more than 60 per cent AN as the only oxidizing material, with the balance as inert material, are usually not considered to be a fire or explosion hazard in storage; but certain additives may render mixed AN fertilizers as hazardous or more hazardous than pure AN.
- Does the fertilizer industry self-regulate?
The Canadian Fertilizer Institute (CFI) is an industry association that represents manufacturers, and wholesale and retail distributors of nitrogen, phosphate and potash fertilizers. Every member must abide by certain requirements established by the CFI as a condition of membership. These requirements include the following:
- The Fertilizer Safety and Security Council’s Ammonia Code of Practice (PDF 1.64 MB)
- The Fertilizer Safety and Security Council's Ammonium Nitrate Code of Practice (PDF 91 KB)
- The CFI policy on melamine
- What steps should fire departments be taking?
Fire departments should be proactive, assess the risks in their communities, and take appropriate measures to reduce the risks:
- determine if there are fertilizer facilities in jurisdiction;
- ensure facilities comply with the Fire Code and have an approved fire safety plan;
- do pre-fire planning:
- identify hazards,
- identify appropriate suppression tactics,
- create or review, as needed, emergency response plans, mutual/automatic aid protocols or agreements that may be invoked in the eventuality of an emergency at a fertilizer facility.
- What resources are available to fire departments?
For any additional assistance, support or clarification, please refer to the contact information in the Fire Marshal’s Communiqué.
- What support is there in the event of a major emergency?
Ontario’s first responders are expected to be trained and prepared to respond to a variety of major incidents.
For larger or more complex incidents, Ontario has additional resources in place to respond to chemical, biological, radiological, nuclear or explosive (CBRNE) incidents and structural collapses/explosions.
Most fire departments in the province of Ontario are trained to the awareness level in hazardous materials emergency incident response. In addition, Ontario has several provincially coordinated specialized response teams made up of highly trained first responders: three teams trained at the ‘technician level’ (advanced), located in Toronto, Windsor and Ottawa; and six support teams trained at the ‘operations level’ (intermediate), located in Peterborough, Cornwall, Sault Ste. Marie, Thunder Bay, North Bay and Waterloo Region.
Together with Toronto’s highly trained Heavy Urban Search and Rescue (HUSAR) team and the Ontario Provincial Police (OPP)’s specialized response team UCRT (Urban Search and Rescue CBRNE Response Team), these teams are available on a 24-7 basis to respond in a timely way across the province to significant emergencies, such as earthquakes, tornadoes, severe storms and explosions.
The Ontario Fire Service Mutual Aid System, established under the Fire Protection and Prevention Act, 1997, and administered by the Fire Marshal, provides the province with an effective mechanism for mobilizing significant emergency response resources for incidents that exceed a community’s available resources. The system consists of an interdependent network of agreements between municipalities to make available their emergency response resources for extraordinary events. The agreements are structured at the county/region/district level and allow for the flexible sharing of resources on a reciprocal basis.
Fire Marshal’s Communiqué 2005-29, Office of the Fire Marshal Resources for Major Incidents, provides information about Office of the Fire Marshal resources and services available to assist in responding to incidents where a ‘provincial’ response is not required but assistance beyond the mutual aid system is needed.