Nearly all industries, including the agri-food industry and the service industry, use chemicals in variable amounts and must therefore store them, as well as the produced chemical waste before disposal. Acting as a warehouse, the storage facility also shelters the chemicals: it protects the personnel and the environment from the effects of a spill, or an aerosol or gas emission. While designing a chemical storage facility, regardless of its size, it is thus essential to take into account all hazardous properties of chemicals, intrinsic or arising from interactions.
Main cause: chemical emissions
Toxicological, chemical and physical properties define the hazards of a chemical. However in a chemical storage facility further factors add on: quantity, storage form, proximity of various chemicals, activities carried out in the facility, etc. The following example illustrates this hazard increase: hydrochloric acid and iron fillings, stored separately, are not flammable, yet when they come in contact, their reaction releases hydrogen, an extremely flammable gas, which may cause fire or explosion.
But the hazard first materialises, when chemicals are spilt, e.g. out of containers. Among numerous causes for a chemical leak are:
- mechanical damage of the container (bumped during transportation, tilted over after it was placed on an unstable ground or rack...);
- container ageing (plastic becoming brittle with time or under the effect of light or low temperatures, plastic softening through heat, metal corrosion, interaction between the container and its filling);
- expansion of the filling (vapour pressure build-up with heat, crystallisation at low temperature, chemical decomposition with time or induced by light exposure);
- sampling and transfer of chemicals.
This chemical dispersion can have serious consequences.
Damage to health
A leaked chemical, especially when it is volatile or a gas at room temperature, can cause intoxication. The risk of intoxication is particularly insidious, when the spilt chemical on its own does not have any severe toxicological property but releases a toxic substance when it reacts with the environment or other chemicals stored in the same room (for instance, gaseous chlorine forms, when liquid bleach comes in contact with an acidic solution).
Likewise irritations to severe chemical burns can happen with corrosive liquids like caustic soda.
Besides these acute effects, a wide range of chronic effects can also occur (such as impaired organ function, allergies and cancers. Contrary to acute effects, the occurrence of those chronic effects does not necessarily depend on the level of exposure: allergies, for example, can be triggered by exposure to very low concentrations of a sensitising agent.
Lastly, among all chemicals categories, liquefied gases constitute a specific hazard. Contact with liquefied gases causes severe frostbites and, even if not toxic, once released, their rapid expansion can locally reduce the oxygen concentration to dangerously low levels and therefore cause asphyxia.
Damage to the environment and facilities
Apart from the hazards they represent for workers’ health, stored chemicals may induce hazards for facilities, fauna and flora, and the general public off site.
When they are spilled, chemicals can irreversibly alter soils, streams and ground waters, thus affecting surrounding communities. The nature of the environmental damage caused by a chemical spill depends on its toxicological, physical and chemical properties (form, reactivity, solubility, persistence, bioaccumulation, etc.) and those of the polluted site (permeation properties, etc.), but pollution risk increases with the amount of stored chemicals.
Stored chemicals can also cause accidental fire or explosions. Fire and explosions account for few occupational accidents each year in the European Union, however, when they happen, they often claim lives and have dramatic environmental and economic consequences.
Hostile fire is an uncontrolled oxidation reaction between combustible matter and an oxidant. Large amounts of both elements can often be found in a storage facility. Oxygen is the usual oxidant involved in fire, while stored goods (organic chemicals like solvents or polymer pellets), packaging materials (plastic bags or containers) or pallets act as combustible matter. Various sources of energy can start a fire, e.g. a spark, heat, an explosion.
Accidental explosions can be either “physical" or “chemical". A physical explosion can happen when, for example, pressure builds up inside a chemical container. Chemical explosions result from chemical reactions: a decomposition (storage of explosive materials) or the inflammation of an explosive atmosphere (storage of flammable chemicals, of oxidising metal dust, etc.). In some cases, the chemical reaction is essentially combustion. Many dusts of combustible materials as diverse as flour and coal can lead to a risk of explosion at critical concentrations in the air.
In order to prevent the risks outlined beforehand, the set-up of a storage facility requires careful planning. Among others the storage facility must:
- prevent exposure to hazardous chemicals, and
- not generate additional risks through its design.
As a first step, the planner needs to compile all requirements:
- volumes to be stored (including the volume of chemical waste, as necessary; chemical waste is to be treated as new chemicals, but should be stored separately);
- diversity of chemicals in term of shelf-life, storage conditions and compatibility;
- organisation’s activities (chemical sampling or transfer activities within the storage facility, for instance: they will require a separated dedicated area with local exhaust and specific spill containment system);
- accessibility (reachability and number/dimensions/operation of apertures) and access control (for instance, access to toxic chemicals or chemicals with narcotic properties is restricted to properly trained and authorised persons);
- legal requirements concerning the storage location and the stored goods (for instance, specific national construction regulations may apply for the storage of environmentally hazardous chemicals).
Concerning legal requirements, chemical storage falls within the scope of three legislative and regulatory frameworks:
- workers’ health and safety;
- protection of the general public;
- environmental protection.
Although the form of Member State legislation and regulations may vary widely in these fields, the objectives are common. Competent national authorities should be consulted in order to get acquainted with the legal provisions in force locally (see links for further reading).
A risk assessment supplements the requirement analysis. Preventive measures are derived from its results. This set of data will enable the planner to define building and operating specifications for the storage facility.
The risk assessment should identify all personnel and environmental risks linked to storage. Beside hazardous properties of chemicals, the assessment should also take into account:
- chemical interactions;
- storage systems;
- delivery and removal;
- traffic and transport of chemicals inside the facility;
- any other activities carried out in or close to the facility;
- emergency response.
Further information can be collected from chemical suppliers and prevention institutes or organisations (see links for further reading).
It is important to note that both requirement analysis and risk assessment need to be repeated on a regular basis and whenever a change is introduced in the storage facility or following any abnormal occurrence (incident, accident, health issue). As a result, new preventive measures may have to be defined.
Alongside the planner’s specifications, the chemical storage facility must respect general prevention principles with regard to localisation, building and equipment.
Setting and provision of safety signs
In principle, the chosen location must be solely dedicated to chemical storage. However, small chemical quantities can be stored in workshops and working rooms, when they are required for the activities carried out in these rooms and when a protected area (for instance, an appropriate chemicals storage cabinet, which is ventilated, with its exhaust duct leading outside) is foreseen for that purpose in the rooms (for the set-up of this protected area, a risk assessment must be carried out, as described above).
Furthermore, the chemical storage must be visibly indicated. Associated hazards must be clearly identified, for instance through appropriate warning signs. The personnel must also be informed about safety requirements before entering the storage location.
All building materials must display chemical resistance, especially towards the stored chemicals. In particular flooring must be damp- and chemical-proof. Moreover, in order to avoid contact with hazardous substances all surfaces should be easy to clean. At the same time a skid-proof flooring will prevent occupational accidents due to falls. Storage facilities should also preferably be constructed of non-combustible materials so as to avoid dissemination of hazardous chemicals, should a fire threaten the storage facility.
Access, alleyways, escape routes
First of all, access to the chemical storage facility is allowed only to authorised personnel. Therefore constructive arrangements should be made in order to control access.
Furthermore access to the facility and its alleyways must be large enough and designed according to the activities carried out (use of handling equipment, for instance). In case of emergency, the rescue teams must also be able to access the storage facility quickly. Thus stairs and steps close to the entrance of the facility should be avoided.
The number of emergency exits depends on the facility size and configuration. Escape doors must be designed in such a way that they open to the outside and that they can be opened easily from the inside without the use of any key (installation of panic bars, for instance).
Containing accidental emissions
Any leakage or spill must be contained, so that it does not mix with other chemicals or reach the sewers. The type and capacity of the spillage receiver will depend on the nature and volume of the stored chemicals. Suitable absorbents (neutralising or incombustible) should be readily available in case of small leakages; information on such absorbents can be found under heading 6 ‘Accidental release measures’ of the safety data sheet (SDS).
Ventilation, air-conditioning, lighting
To prevent the accumulation of hazardous vapours, the storage facility must be ventilated, with the air renewal rate adapted to the stored chemicals and the activities carried out in the facility. Air inlet and outlet should be placed so as to avoid any ‘dead’ zone.
Moreover, if frost or heat can damage products and packaging, air conditioning must be foreseen in the facility. Information on temperature sensitivity can be found in the chemicals safety data sheet (SDS) under heading 7 ‘Handling and storage’.
Aside from these requirements, the whole facility must be sufficiently illuminated, so that labelling can be easily read, and damaged packaging or abnormal occurrences can be detected in time.
Storage racks or cabinets must display chemical resistance. They should also be made from incombustible material so as to prevent the escalation of an incident and the spread of a fire.
Particular attention must be paid to the maximum load of racks and cabinets (to be clearly indicated on these). The mechanical resistance of the storage systems must be adapted to the stored goods. In addition, the storage system configuration must prevent any tilting of the containers.
Furthermore, it must be easy to place and remove the chemicals from storage. Therefore, suitable handling equipment must be made available, as necessary.
Prevention of fire and explosions
In order to limit the impact of a fire, preventive measures must be taken, especially when the storage facility contains combustible or toxic material. Those include building and fire-fighting elements such as:
- incombustible and heat-resistant building material;
- fire-proof doors and windows;
- avoidance of ignition sources in the facility (lightning protection, heat sources like light bulbs or air heater away from combustible goods...);
- air-conditioning in order to stay below the flammable substances ignition points;
- fire and smoke detectors, and alarms;
- (fixed or mobile) fire extinguishers.
Moreover, combustible gases, combustible dust or flammable liquids can form an explosive atmosphere when they are released from their packaging. When such chemicals are stored, further measures must be taken such as:
- efficient ventilation in order to stay under the lower explosive limits of the substances;
- encapsulated lighting bulbs;
- use of electrical equipment allowed for areas, where an explosive atmosphere can appear;
- use of explosion-proof tools;
- avoidance of electrostatic loading through use of antistatic flooring and equipment;
Structural preventive measures are of prime importance for a secure chemical storage. For the protection of workers, the public off site and the environment, however, they need to be supplemented by organisational preventive measures, while operating the chemical storage facility. The objective is to avoid hazardous situations and, in particular, to limit exposure by optimising chemical handling.
Roles, procedures, rules of conduct
The employer has a legal responsibility to protect the health and safety of his/her staff and the environment. He/she must thus assess the risks associated with the chemical storage facility, implement the appropriate preventive measures, control their effectiveness on a regular basis and ensure their maintenance.
In this context the employer must inform his/her staff about the risks and preventive measures and provide them with relevant training, including, among others, the following rules of conduct, the respect of which is essential in a chemical storage facility:
- access for authorised personnel only;
- no smoking;
- prohibition of food and like products (beverages, chewing-gum, medicine, tobacco...);
- wearing of prescribed work clothes and personal protective equipment;
- separation of work and street clothes and obligation to change and wear street clothes to enter canteens, for instance;
- changing of work clothes and personal protective equipment, as soon as they are contaminated;
- hand washing before breaks and at the end of workday;
- use of prescribed handling equipment and tools;
- respect of handling (no storage out of specified spaces), cleaning and emergency procedures;
- information about and guidance for any abnormal occurrence
- maintenance and functionality checks (for example, checking the proper functioning of technical equipment, such as handling equipment and the ventilation system, before use).
The larger the stored volumes, the greater the hazard. Moreover, unused chemicals become chemical waste, which generates additional risks. As a result, stock must be minimised in accordance with the organisation’s activities, and a ‘first in, first out‘ rule must be observed.
Without proper packaging, labelling and an up-to-date safety data sheet (SDS) a chemical should not be accepted in the storage facility. There may be exceptions to this rule: for instance, products for the general public (all relevant safety information must appear directly on their labels) or food additives (in this particular case, safety advice should be requested form the supplier).
Chemicals should be stored in their original container. However, if a transfer proved necessary, the chemical should be transferred in a suitable container with proper labelling: chemically, mechanically and thermally resistant, easy to handle with the existing equipment and tools and easy to store with the existing systems.
Maximum loads of storage systems must be respected as well as stacking rules. Moreover containers should be stored in such a way that their labelling can be easily read and that a leakage or damage can be easily seen and dealt with quickly.
Separation of incompatible chemicals
Such incompatibilities are usually described under headings 7 and 10 (‘Handling and storage’ and ‘Stability and reactivity’, respectively) of the SDS. Safety institutes or organisations can also provide useful information about the reactivity of specific substances (see links for further reading).
Finally, in event of an accident, staff must react quickly and in an appropriate way. The employer must therefore draw up emergency procedures, install emergency and first aid equipment as necessary, and inform and train his/her staff accordingly.
Emergency procedures include:
- actions to be taken in case of a chemical accident;
- use of alarm systems;
- emergency call numbers;
- names of contact persons;
- evacuation instructions;
- first aid measures.
On top of safety training, evacuation drills must be organised regularly and first-aiders must be named and trained.
Furthermore when a number of different chemicals are stored, it is recommended to establish an inventory of all stored products as well as a storage plan, to keep them up to date and to have them readily available in case of an accident. These records should inform about the products, their quantities and their location in the storage facility and therefore avoid that the emergency and rescue teams expose themselves to additional risks during their intervention. Then, regular consultation with the local fire and rescue authorities will help them action the appropriate response in case of emergency.
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European standards on fire classification of construction products and building elements: EN 13501-1:2007 Fire classification of construction products and building elements - Part 1: classification using data from reaction to fire tests.
EN 13501-2:2004 Fire classification of construction products and building elements - Part 2: classification using data from fire resistance tests, excluding ventilation services.
EN 13501-3:2007 Fire classification of construction products and building elements - Part 3: classification using data from fire resistance tests on products and elements used in building service installations: fire resisting ducts and fire dampers.
EN 13501-4:2007 Fire classification of construction products and building elements - Part 4: classification using test data from fire resistance tests on smoke control systems.
EN 13501-5:2007 Fire classification of construction products and building elements - Part 5: classification using data from external fire exposure to roofs tests.
European standards on fire safety storage cabinets: EN 14470-1:2004 Fire safety storage cabinets - Part 1: Safety storage cabinets for flammable liquids.
EN 14470-2:2006 Fire safety storage cabinets - Part 2: Safety cabinets for pressurised gas cylinders.
List of national standardisation organisations, where these standards can be purchased: http://www.cen.eu/cen/Members/Pages/default.aspx
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