Spraying flammable liquids
Guidance for employers on how to eliminate or reduce the workplace health and safety risks when spraying flammable liquids.
Under the Occupational Health and Safety Act 2004 (OHS Act), employers must, so far as is reasonably practicable:
- provide and maintain a working environment that is safe and without risks to the health of employees, including independent contractors
- provide employees with the necessary information, instruction, training or supervision to enable them to do their work in a way that is safe and without risks to health
- make arrangements for ensuring safety and the absence of risks to health in connection with the use, handling, storage or transport of substances
Where the risk cannot be eliminated, it must be reduced so far as is reasonably practicable.
Employers also have a number of specific duties under the Occupational Health and Safety Regulations 2017 to manage risks associated with hazardous substances in the workplace.
The Dangerous Goods (Storage and Handling) Regulations 2022 also sets out legal duties for occupiers of premises where dangerous goods are stored or handled.
Flammable liquids are common in the vehicle refinishing and furniture manufacture industries. These liquids can affect an employee’s health and cause fires and explosions.
Flammable liquids that can be applied by spraying include:
- paints and hardeners
- paint removers
Spray methods for flammable liquids may include:
- conventional compressed air
- high volume low pressure (HVLP)
Conventional compressed air spraying has significant overspray, which can be inhaled. This method should only be used when other spray methods cannot.
Flammable liquids are dangerous goods and most would also be hazardous substances. Dangerous goods are classified based on immediate effects such as fire, explosion, corrosion or poisoning while hazardous substances are classified based on health effects whether they be immediate or long term.
A red diamond-shaped label, shown in figure 1, identifies a dangerous good that is a flammable liquid.
Many flammable liquids are also hazardous substances which present a health hazard and are identified by one of 9 symbols which communicate the classification of chemicals.
Risks associated with spraying flammable liquids are:
- fire and/or explosion due to the flammable nature of the substances used
- health risks which may result in either short or long term health effects
Fire and explosion risks
Fire or explosion can occur due to the accumulation of the vapours from spraying flammable liquids and the presence of an ignition source, which can include:
- sparks from electrical switches and equipment
- naked flames (welding or cutting, lit cigarettes and heaters)
- portable battery powered equipment (radios, mobile phones)
- static discharge from poorly earthed equipment
Health effects can include:
- irritation to the eyes, nose and throat
- loss of coordination
- respiratory sensitisation (asthma-like symptoms including chest tightness, breathlessness and wheezing), particularly from paint containing isocyanates
Specific information on the health hazards of the flammable liquid being sprayed can be found in the safety data sheet for that substance, which is available from the manufacturer, importer or supplier.
Hierarchy of control
Use the hierarchy of control to control risks in the workplace. The hierarchy of control is a step-by-step approach to eliminating or reducing risks and it ranks risk controls from the highest level of protection and reliability through to the lowest and least reliable protection.
The most effective way to control risk of fire and effects to health is to eliminate the use of the flammable liquid.
Reduce the risk with one or more of the following controls:
Substitute the risks with lesser risks.
Substitution includes using a less hazardous substance or applying it by a less hazardous method, for example:
- apply with a brush or roller
- use water-based instead of solvent-based paints
- use lead-free instead of lead-based paints
Isolate people from the risks by distance or the use of barriers.
Reduce the risks through engineering controls such as mechanical ventilation or spray booths.
Where it is reasonably practicable, a spray booth should be used to control exposure to hazardous substances and minimise the risk of fire or explosion.
A spray booth should:
- be constructed of non-combustible, impervious materials — usually steel, with a smooth finish
- have no ignition sources, including unsealed lights, within the booth or within 2 metres of the open face of the booth
- have effective air filters or a water wash system to remove paint mist, which are maintained in good condition
- have the air flow at the point of spraying at least:
- 0.5 metres per second for side draught booths
- 0.25 metres per second for full down draught booths
- have an exhaust stack which vents with vertical discharge outside the building
- the object being sprayed is always between the operator and the point of exhaust
- the booth is always operating during spraying and continues to operate for at least 5 minutes after spraying has ended until residual overspray has been removed
Use administrative actions to minimise exposure to hazards and to reduce the level of harm.
Administrative controls for reducing the risk when using flammable liquids, for example:
- If spraying can't be done in a spray booth, ensure there are no ignition sources within 6 metres in any direction horizontally and 2 metres vertically above the item being sprayed.
- Ensure that containers of flammable liquids are always fitted with a lid.
- Ensure any spills are cleaned up immediately and solvent-soaked rags are disposed of in lidded containers.
- Restrict access to only those who need to be in the spraying area.
PPE is the least preferred option for controlling risk and should only be used to supplement higher order controls when those controls cannot adequately protect employees.
Examples of PPE include respirators and gloves.
Respirators can be full face or half face and they can be filtering or air-line type.
Examples of situations where air-supplied respirators will be required include:
- spraying of highly toxic isocyanate-containing paints, including when spraying in a spray booth (see Precautions for isocyanates)
- spraying of flammable liquids in a confined space
Examples of situations where air purifying (filter type) respirators are likely to be required include:
- spraying of large quantities of flammable liquids when not spraying in a spray booth
- spraying large objects in a spray booth where the extraction system may not capture the spray mist adequately.
Maintenance of controls
Spray booths, respirators and compressors supplying breathing air (see Standards Australia) should be regularly checked and properly maintained in good operating condition. Employers should also keep all records of testing, maintenance and repair work for the life of the plant and equipment.
Information and training
This should include:
- health and safety hazards of the substance being sprayed (read the safety data sheet that comes with the product)
- the proper use of risk control measures and why employees should use the controls provided
Precautions for isocyanates
Spraying of 2-pack lacquers and paints containing isocyanates is common in auto refinishing and the manufacture of wood products. These coatings are supplied in 2 parts that are mixed together. The hardener component (usually part B) contains isocyanates, which can also be called polymeric isocyanate or isocyanate pre-polymer.
Respiratory sensitisation is the main hazard associated with isocyanates. This may occur after a single high exposure or after longer term exposure at lower concentrations. Once a person becomes sensitised, any exposure to isocyanates (even extremely small doses) can result in asthma-like symptoms including chest tightness, breathlessness and wheezing. Such attacks have on rare occasions resulted in death.
Spray painters who become sensitised usually can no longer work in the industry.
When spraying isocyanate-containing 2-pack paints and lacquers, you should:
- perform the work in a spray booth (see Standards Australia) with an airflow of at least:
- 0.25 metres per second for a full down draught booth
- 0.5 metres per second for all other booths.
- wear a full face air-supplied respirator or hood
- be provided with health surveillance conducted by a registered medical practitioner (see Guidelines for health surveillance: Isocyanates, under regulations)
If spraying can’t take place in a spray booth, anyone within 20 metres of the spraying should be provided with a full face air-supplied respirator or hood.
After spraying, there should be a 30 minute interval to clear the spray mist before any unprotected person can enter the 20 metre exclusion zone.