Storage of Flammable Liquids and Gases, what did the supervisor cover under GHS

Under GHS Flammable liquids are defined as those with a flash-point (temperature at which a substance gives off sufficient vapor for it to form an ignitable mixture with air) below 55°C. Flammable materials are substances that can ignite easily and burn rapidly. They can be common materials that are at most work sites in gas, liquid and solid forms. Some examples of flammable materials include: Gases — Natural gas, propane, butane, methane, acetylene, carbon monoxide, hydrogen sulphide. Flammable gases are usually gases with a lower explosive limit of less than 13 percent in air, or have a flammable range in air of at least 12 percent. For example, butane is a flammable gas because its lower explosive limit in air is 20 percent. Carbon monoxide has a lower explosive limit of 13 percent and upper explosive limit of 74 percent in air, it is flammable over a range of 61 percent.

GHS and Flammable Liquids and Gases are not just about safety it covers a lot of items including fire control. Fire prevention consists of making sure that the three elements are not present together in right amounts for a fire to occur. For example, vapours from a flammable liquid must be mixed with a certain amount of air and exposed to the right amount of heat to ignite and burn. Other critical factors include: ƒ the mixture must be within the explosive range (above the lower explosive limit and below the upper explosive limit); ƒ the minimum level of energy required to light the flammable mixture must be present. The ignition source must be at a high enough temperature, be of sufficient size and applied for enough time for ignition to occur; ƒ physical factors such as the container/vessel the materials are in, flow velocity and turbulence (affects mixing). Once vapours from a flammable liquid have ignited, the flames may “flash-back”. This means the flames travel back, through the vapour air mixture, to the container or source of the flammable liquid. This can create an explosion. Most flammable liquids produce vapours that are heavier than air. Some flammable gases are also heavier than air. These gases and vapours can spread a considerable distance along the ground or floor and be ignited by a distant spark or flame or source of heat. Certain chemicals such as organic peroxides (e.g. benzoyl peroxide) contain both fuel and oxygen. Special extra attention is needed for the safe handling and storage of these materials. For a flammable or combustible liquid fire to start, a mixture of vapour and air must be ignited. There are many possible ignition sources:

  • Sparks from electrical tools and equipment.
  • Sparks, arcs and hot metal surfaces from welding and cutting.
  • Tobacco smoking.
  • Open flames from portable torches and heating units, boilers, pilot lights, ovens, and driers.
  • Hot surfaces such as boilers, furnaces, steam pipes, electric lamps, hot plates, irons, hot ducts and flues, electric coils and hot bearings.
  • Embers and sparks from incinerators, foundry cupolas, fireboxes and furnaces.
  • Sparks from grinding and crushing operations.
  • Sparks caused by static electricity from rotating belts, mixing operations or improper transfer of flammable or hot combustible liquids.

You can eliminate many of these ignition sources by:

  • Removing open flames and spark-producing equipment.
  • Not smoking around these liquids.
  • Using approved explosion-proof equipment in hazardous areas.

There are two main dangers present:

  • Explosion – which would result when flammable vapours and air mixtures fall within explosive limits
  • Fire – which may involve the flow of burning liquid over a wide area or the rupture of unventilated containers

Remember that although a flammable liquid may have a higher flashpoint it will, nonetheless, when involved in a fire; greatly contribute to the severity and spread of the fire.


apply to:

Glossary Boiling Point – The temperature at which a liquid usually changes to a vapour at normal atmospheric pressure.

Closed Container – A container sealed by a lid or other device in a way that liquid or vapour will not escape from it at ordinary temperatures

Combustible Liquid – A liquid having a flash point at or above 37.8°C and below 93.3°C. These are subdivided into Class II and Class IIIA liquids.

Combustibles – Any solid, liquid, or gaseous material (e.g., wood, paper, cardboard, cloth) not classified as “flammable” that is capable of catching fire and burning.

Dangerous Goods – Products or substances regulated by the Transportation of Dangerous Goods Act (Canada) and its Regulations.

Fire Compartment – Areas in the workplace where specified quantities of flammable or combustible liquids are stored. Unless the containers are stored in metal cabinets, fire separations must generally be installed between fire compartments.

Fire Resistance Rating – The time in hours that a material will withstand flames or heat passing through when exposed to fire under specified conditions of test and performance criteria.

Flammable Liquid – A liquid with a flashpoint below 37.8°C and lowering a vapour pressure not more than 275.8 kPa (absolute) at 37.8°C

Flammable Liquids Storage Flash Point – The lowest temperature at which a flammable liquid, within a container, gives off enough vapour to form an ignitable mixture with air near the surface of the liquid. General Storage Area – Indoor storage area, as covered in Subsection 3.2.3 of the National Fire Code of Canada, where commodities or plastics are stored in piles, on pallets, on shelves or in bin boxes or racks.

Hazardous Room – A room containing a substance which, because of its chemical nature, the form in which it exists or the manner in which it is handled or processed, may explode or become easily ignitable creating a condition of imminent hazard to a person’s health or safety.

Incidental Use – Storage and use of flammable liquids is incidental or secondary to the principal activity in the industrial workplace. Manufacturers of electronic equipment and furniture, and automobile plants are some example of locations where the storage and use of flammable liquids is secondary to the principal activity of manufacturing consumer products.

Individual Storage Area – An area occupied by piles, bin boxes, racks or shelves, including aisles providing access to stored product, which is separated from adjacent storage by aisles at least 2.4 metres wide.

Industrial Workplace – A building or part of a building used to assemble, fabricate, manufacture, process, repair or store goods or materials.

Oxidizer – A substance that causes or contributes to the burning of another material by yielding oxygen or any other oxidizing substance. Pile – Groups of containers (i.e., drums or other prepackaged containers) of flammable liquids that are stacked or piled on floors or pallets.

In the USA OLD

CFR 1910.106

Before it was aligned with GHS, 29 CFR 1910.106 gave these definitions for flammable and combustible liquids:

  • A flammable liquid was defined as “Any liquid having a flash point* below 100°F (37.8°C)”
  • A combustible liquid was defined as “Any liquid with a flash point at or above 100°F (37.8°C), but below 200°F (93.3°C)”

Flammable and combustible liquids were further subdivided into classes:

  • All flammable liquids were Class I liquids.
    Class IAliquids had flash points below 73°F (22.8°C) and boiling points below 100°F (37.8°C).
    Class IB liquids had flash points below 73°F (22.8°C) and boiling points above 100°F (37.8°C).
    Class IC liquids had flash points at or above 73°F (22.8°C) and below 100°F (37.8°C)
  • Combustible liquids were Class II or III liquids.
    Class IIliquids had flash points at or above 100°F (37.8°C) and below 140°F (60°C).
    Class IIIA liquids had flash points at or above 140°F (60°C) and below 200°F (93.3°C)
    Class IIIB liquids had flash points at or above 200°F (93.3°C). When these chemicals were heated within 30°F (16.7°C) of their flash points, they were treated as Class IIA liquids.



Under GHS, all liquids with a flash point of not more than 199.4°F (93°C) are categorized as flammable liquids. Flammable liquids are further subdivided into categories:

  • Category 1 liquids have flash points below 73.4°F (23°C) and boiling points at or below 95°F (35°C).
  • Category 2 liquids have flash points below 73.4°F (23°C) and boiling points above 95°F (35°C).
  • Category 3 liquids have flash points at or above 73.4°F (23°C) and at or below 140°F (60°C). When Category 3 liquids with flash points at or above 100°F (37.8°C) are heated for use to within 30°F (16.7°C) of their flash point, they must be handled in accordance with the requirements for a Category 3 liquid with a flash point below 100°F (37.8°C).
  • Category 4 liquids have flash points above 140°F (60°C) and at or below 199.4°F (93°C). When Category 4 flammable liquids are heated for use to within 30°F (16.7°C) of their flash points, they must be handled in accordance with the requirements for a Category 3 liquid with a flash point at or above 100°F (37.8°C).
  • In addition, the new rules specify that when a liquid with a flash point greater than 199.4°F (93°C) is heated for use to within 30°F (16.7°C) of its flash point, it must be handled in accordance with the requirements for a Category 4 flammable liquid.
  • Extremely flammable liquids and gases (Flashpoint (FP)) <0°C and BP <35°C
  • Highly flammable liquids FP <21°C
  • Flammable liquids FP 21°C – 55°C

The standards also applies to explosives, oxidising agents, flammable dusts and other substances which create similar risks.

With highly flammable liquids and liquefied petroleum gases (LPG) in mind. Storing Flammable Liquids To store flammable liquids safely, or if you are designing a flammable liquids storage area, consider the following: ● design and construction of storage containers ● the class of flammable liquids ● the quantity to be stored ● your storage location ● how it will be used ● ventilation ● fire protection ● control of ignition sources Storage Containers Containers used to store flammable or combustible liquids, having a capacity of not more than 230 litres, must conform with one of the following: ● the “Transportation of Dangerous Goods Regulations” ● CSA B376-M (R2003) “Portable containers for Gasoline and Other Petroleum Fuels” (up to 5 gallons/25 litres) ● ULC/ORDC30 “Safety Containers” ● CSA-B306, “Portable Fuel Tanks for Marine Use” ● Section 6 of CSA-B620, “Highway Tanks and Portable Tanks for the Transportation of Dangerous Goods” Containers of not more than 1 litre capacity used for flammable liquids (5 litres for combustible liquids) are exempt from the above requirement.

Key Action Steps

  • Define which flammable liquids and gases on site come under REGULATIONS AND STANDARDS
  • Carry out a risk assessment review
  • All storage must be in a “safe position” – generally in the open air – or in a “fire resisting structure” in suitable closed vessels.
  • A maximum of 50 litres of extremely and highly FL and FL with FP <32°C may be kept in a fire resistant cupboard or bin in a workroom.
  • Keep openings in storage vessels and tanks closed when not in use so that vapours do not escape and there is no contamination of the enclosed liquid.
  • FL and gases storage vessels and containers should be suitably marked.
  • Storerooms should be secured with limited access to authorized personnel only.


Risk Assessment

Factors to be taken into account when assessing flammable liquid storage installations and LPG include:

  • Properties of the substances being stored
  • Information provided by the supplier
  • The quantities being stored
  • Storage method in bulk tanks or containers
  • Temperature and pressure of the storage
  • Location in relation to site boundaries occupied buildings, means of escape, process areas, heat sources, fixed sources of ignition, other dangerous substances and vehicle routes
  • Design standards for the installation
  • Possibility of corrosion
  • Activities on adjacent premises
  • Training and supervision of employees
  • Frequency of deliveries
  • Loading and unloading operations
  • Inspection and maintenance
  • Incidents and emergencies
  • Security

Control Measures

If possible consider elimination of risks by substitution with non flammable liquids or gases. If this is not possible the following control measures should be applied:

  • Dangerous substances that are gases, liquids or liquefied gases should be stored in closed tanks, cylinders or containers constructed to an appropriate national or international standard
  • Liquids stored above ground should have a means to contain leaks and prevent any spillages. Underground storage tanks should be provided with secondary containment or a leak detection system
  • Liquid leaks from fixed LPG storage vessels should be directed away from the vessel and other vulnerable locations to an area where the vapours evaporating from the leak can readily and safely disperse.


Storage areas should be adequately separated from site boundaries, occupied buildings, process areas, fixed sources of ignition and other dangerous substances. The separation should be sufficient to allow people to escape from a fire at the store and should also be sufficient to protect the store from fires that may occur elsewhere including on the boundary. The separation should prevent or delay the spread of fire allowing sufficient time for emergency procedures to be mobilized.

Class What is the class of the flammable liquid? Flammable liquids have flash points below 37.8°C, and include solvents such as acetone, ethyl alcohol and xylene. They are classified according to their flash points and boiling points as follows: Flash Point Boiling Point Class 1A below 22.8°C below 37.8°C Class 1B below 22.8°C at or above 37.8°C Class 1C at or above 22.8°C but below 37.8°C , The lower the flash and boiling points, the more hazardous the liquid; therefore, the storage restrictions are greater. If liquids with flash points at or above 37.8°C are stored at temperatures above their flash points, they must be stored as Class 1 liquids. To determine the flash and boiling points of the liquids you will be storing, consult your suppliers’  safety data sheets (SDSs). Quantity What is the quantity to be stored? Small quantities, up to 250 litres* of flammable liquids (or 600 litres of flammable and combustible liquids), in closed containers, may be stored outside of fire-separated rooms or storage cabinets, in any one fire compartment. Of this, not more than 100 litres shall be Class 1A liquids. Greater quantities may be stored but must not exceed one day’s normal requirements. (*note: the Fire Code does not have the 250 L restriction for flammable liquids) It is advisable not to store any quantity of flammable liquids in basement areas*.  Do not store containers in or near exits (either inside the building or outside), elevators or access routes to exits. What about quantities above 250 Litres? For quantities greater than 250 litres, in closed containers, you have the following storage options: ● in metal cabinets ● in a general storage area in the ● in a fire-separated room in the workplace ● outdoors ● flammable liquid warehouse

Outdoors, adequate separation can be achieved by an appropriate distance or by using a fire-resisting wall.

Where liquids or gases are stored inside buildings, the storeroom should be a dedicated building or a separate room within a building. The store should be adequately separated from buildings, workrooms and potential hazards or be fire-resisting.


Incompatible dangerous substances should be segregated or adequately separated to minimise the risk of interaction.


Good ventilation should be provided in areas where flammable liquids or gases are stored to ensure that any gases or vapours given off from a spill, leak or release are rapidly dispersed. Storage areas should preferably be located in well-ventilated positions, in the open air. If within a building, adequate natural or mechanical ventilation to the outside of the building should be provided

Identification of Storerooms, Tanks, Vessels and Containers

Contents of tanks, vessels and containers, should be clearly identified so that employees or others are aware of their contents and hazards. Similar considerations apply to cupboards, compounds and storerooms.

Material Transfer

Flammable liquids and gases should be carried in closed vessels or conveyed in a totally closed system incorporating pipelines and pumps or similar. The contents of pipes, fill points and discharge points should be identified. Where a totally enclosed system cannot be used substances should be carried or conveyed in closed containers or vessels that minimize the risk of spills or releases.

Process activities, including dispensing or decanting should not be carried out in a storage area where this would create a risk of fire involving the stored materials.

Loading and unloading facilities should be designed, located and operated to avoid or minimize the risks of fire and explosions at either the transfer facility or the storage installation. The facility should include measures to minimize the risks of leaks, spills and overfilling plant and equipment.

Control of Ignition Sources

Areas where potentially explosive atmospheres could be formed should be designated as hazardous zones according to the principles of Hazardous Area Classification.

Storage in Process Areas and Workrooms

The quantity of any dangerous substance present within process vessels, pipelines, pumps, plant and other associated equipment should be as small as is reasonably practicable.

Small quantities of flammable liquids (FL) in closed containers can be stored within the workroom in a suitably placed cupboard or bin which is of fire-resisting structure and is designed to retain spills.

For FL that have a FP above 32°C, this quantity is considered to be up to 250 litres. For extremely and highly FL and those FL with a FP below 32°C the quantity is up to 50 litres.

At retail premises, where products are present in closed or sealed containers, the quantity of dangerous substance at the point of sale should be kept to a minimum consistent with the needs of the business.

Containers that are nominally empty but may still contain residues of dangerous substances should be removed from the workroom and stored in the same manner as full containers.

All openings in cupboards, bins, tanks, vessels and containers whether containing a dangerous substance or nominally empty, should be kept closed except at necessary for their use, operation or maintenance


Employers should ensure that adequate security arrangements are provided to prevent unauthorized access to dangerous substances and associated storage equipment.


Storage facilities must be maintained in a safe condition. They should be subject to an appropriate inspection program to establish that they remain fit for purpose. This should be carried out by a competent person


Store flammable and combustible liquids in areas that are:

  • well ventilated to reduce vapour concentrations.
  • free of ignition sources.
  • cool (temperature controlled) and dry.
  • supplied with adequate firefighting and spill clean-up equipment.
  • away from elevators, building and room exits, or main aisles leading to exits.
  • accessible by firefighters.
  • labelled with suitable warning signs. For example: “No Smoking”.

Avoid storing flammable and combustible liquids in basements. Ground floor storage is usually preferred as it provides easier access for emergency situations.

Inspect storage areas regularly for any deficiencies such as damaged or leaking containers, poor ventilation or non-approved equipment. Unapproved modifications or damage to approved or explosion-proof equipment or systems could result in unintended hazardous conditions. Correct all deficiencies as soon as possible.

It may be possible to store small amounts of flammable liquids (less than 235 litres or about 62 U.S. gallons) and combustible liquids (less than 470 litres or about 124 U.S. gallons) in approved containers in specially designed storage cabinets near their point of use.

Volatile, flammable liquids are sometimes stored in refrigerators. Use specially designed and approved refrigerators (generally described as “laboratory safe”) for this. Standard domestic refrigerators contain many ignition sources and should not be used for storing flammable solvents.

Be ready to handle emergencies safely. In emergencies like chemical fires and spills, act fast.

  • Leave the area at once if you are not trained to handle the problem or if it is clearly beyond your control.
  • Alert other people in the area to the emergency.
  • Call the fire department immediately.
  • Report the problem to the people responsible for handling emergencies where you work.
  • Obtain first aid if you have been exposed to harmful chemicals and remove all contaminated clothes. Emergency eyewash stations and safety showers should be present wherever accidental exposure to materials that can damage skin or eyes might occur.

Only specially trained people, equipped with the proper tools and protective equipment, should handle the emergency. Nobody else should go near the area until it is declared safe.

Planning, training and practicing for emergencies are important so that everyone knows what they must do.

The SDSs for the materials you are using are a good starting point for drawing up an emergency plan. SDSs have specific sections on fire and explosion hazards including suitable fire extinguishing equipment and methods (using the wrong fire extinguisher or using it incorrectly is dangerous), spill clean-up procedures, and first aid instructions. If the directions in each SDS section are not clear or seem incomplete, contact the material’s manufacturer or supplier for help.

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