Physiochemical hazards: safe chemical handling to prevent injuries, deaths, and property damage

Dec 26, 2018 Posted by Walter Ingles

Hazardous chemicals have physical hazards that can immediately cause the death or injury to your workers, damage property; or harm the environment. When these physical hazards (like being flammable, explosive, or reactive) are combined with incorrect storage and inappropriate handling techniques, a physiochemical hazard is created. This blog identifies the physical hazards of chemicals (including their hazard classes), and explains what they are along with our professional  guidelines for safe handling and storage. Use the contents to support your chemical risk assessments and safety audits.


NOTE: This blog discusses how chemicals present physical hazards, for information on health hazards (eg, how chemicals enter the body to cause illness and disease) please read our recent article Chemical health hazards: how hazardous chemicals can damage the health of your workers.

Physical hazards of chemicals

A chemical is a physical hazard if it can burn or support fire; explode or release high pressure that could injure someone; or spontaneously react (either on its own or when exposed to water). We’ll look at these three physical hazards (fires, explosions, spontaneous reactions) and their sub-categories (or hazard class) below:

1. Fire Hazards

Fire hazards include anything that can burn or support fire.

  • Combustible and Flammable Liquids: do not actually burn, what burns is a mixture of the vapours emitted by the chemical and the air. It’s important for staff to understand the flashpoint of these liquids; which is the lowest temperature the liquid can emit enough vapour to start burning. Examples of flammable and combustible liquids include: petrol, acetone, eucalyptus oil, mineral turpentine, kerosene, and methylated spirits.

  • Flammable Aerosols: projects a flame (more than 45cm) when the valve is fully opened, or projects any flashback. Examples of flammable aerosols include: spray paints and adhesives.

  • Flammable Gases: are gases that can ignite at 20ºC air temperature with standard pressure of 101.3 kPa (1 atmosphere). Examples of flammable gases include: LPG, acetylene, natural gas, hydrogen, butane, methane, carbon monoxide.

  • Flammable Solids: can be ignited by friction, absorbing moisture, spontaneous chemical change, or from retained heat during manufacturing or processing (as well as other ignition sources). Examples of flammable solids include: asphalt, grease and fat, wax, shellac, and bitumen.

  • Oxidisers: initiate or promote combustion in other materials. Examples of oxidisers include: aluminium nitrate, barium peroxide, hydrogen peroxide, and silver nitrate.

  • Pyrophoric Chemicals: are chemicals that will ignite spontaneously when exposed to air. Examples of pyrophoric chemicals include: lithium, powdered aluminium, and magnesium.

2. Explosive Hazards

An explosive is any chemical that can cause a sudden (almost instantaneous) release of pressure, gas, and heat. They can be activated by sudden shock, pressure, or high temperature.

  • Explosives: are unstable materials that can either detonate or burn at a subsonic rate. Examples of explosives include: nitroglycerine and TNT (detonators), gunpowder, and rocket fuel.

  • Compressed gases: all compressed gases have the potential to explode because they are stored at high pressure. The rupture of a cylinder and rapid release of the gas creates a great force and can propel a heavy, metal gas bottle like a missile. Examples of compressed gases include: chlorine, LPG, argon, helium, and oxygen.

3. Reactive Hazards

Reactive chemicals cause harm by releasing gases and other substances that burn, explode, produce high pressure, or are more toxic than themselves.

  • Organic peroxides: are organic compounds with double oxygen atoms (known as peroxy).  The double oxygen makes organic peroxides useful but chemically unstable. Organic peroxides can be flammable, explosive, toxic, and corrosive. The rubber and plastics industries use organic peroxides as accelerators, catalysts, cross-linking agents, curing agents, and hardeners. Examples include: acetyl peroxide and dry dibenzoyl peroxide.

  • Unstable (reactive) chemicals: decompose, condense, polymerize, or become self-reactive when exposed to shock, pressure or certain temperatures. Examples of unstable chemicals include: acrylonitrile and butadiene.

  • Water-reactive chemicals: react with water and release either a flammable or hazardous gas (cyanide or acetylene). Examples of water-reactive chemicals include: calcium carbide.

IMPORTANT: read the Safety Data Sheet (SDS) carefully to understand the physical hazards (all hazard classes) of the chemicals you introduce and use to the worksite.

Handling chemicals safely

Handling and storing chemicals safely always begins with understanding the chemicals and their physical properties and hazard classes. Once these are known you will need to:

  • Provide staff with suitable Personal Protective Equipment (PPE) like chemically resistant gloves, face shields, and masks that fit perfectly; then train them how to use the PPE, keep it clean, and put it away. You should provide a dedicated PPE cabinet to keep this essential equipment safe from dust and vermin and ensure it is always ready for use.

  • Have good housekeeping practices: quickly deal with chemical spills; don’t leave potentially hazardous materials lying about on lab benches or the workshop; and dispose of hazardous waste correctly.

  • Have spill cleanup kits for each type of chemical readily available.

  • Install eyewash stations, emergency showers, and first aid kits then ensure staff know their location and how to use them.

  • Ensure that work areas have sufficient ventilation to keep work areas within safe chemical exposure limits.

TIP: For a detailed guide to introducing a chemical risk management methodology download our free eBook How to manage the risk of Hazardous Chemicals in the workplace.

Storing hazardous chemicals correctly

Storing hazardous chemicals correctly is a result of a thorough chemical risk assessment including extensive review of the Safety Data Sheets. Purchasing a ready-made chemical safety cabinets (eg, flammable liquids store or an organic peroxide cabinet) is only part of a process. Your will need to ensure that:

  • Incompatible chemicals and Dangerous Goods are not stored together.

  • Toxic substances are secured from untrained and unauthorised personnel.

  • Compressed gases are properly separated then segregated by hazard class.

  • Aerosol cans are stored in a cage or cabinet that has sufficient projectile protection.

  • Flammable liquids cabinets have self-closing doors and a compliant spill containment sump.

  • LPG and other flammable gases are stored at least 5 metres from refuse stations, combustible, and vegetation

  • Chemical containers are stored with the lids closed when they are not in use.

  • All containers (including portable units) are correctly labeled.

TIP:  Compressed gases are also hazardous chemicals, we encourage you to download our free eBook Gas Cylinder Storage: Compliance and safety requirements.

Next Steps

If you would like more information on how to manage the risk of hazardous chemicals in the workplace, feel free to download our free eBook that outlines our methodology for managing the risk associated with hazardous chemicals. You can download this now by clicking on the image below:

How to manage the risk of hazardous chemicals in the workplace

Walter Ingles

Walter Ingles Compliance Specialist

Walter is STOREMASTA’s Dangerous Goods Storage Specialist. He helps organisations reduce risk and improve efficiencies in the storage and management of dangerous goods and hazardous chemicals.

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