Hierarchy of Control: Isolating and segregating hazardous chemicals

Jul 8, 2020 Posted by Walter Ingles

The Hierarchy of Control is an accepted methodology for assessing and introducing control measures to eliminate (if possible) or minimise workplace risks and hazards. This blog provides a brief introduction to the Hierarchy of Control and focuses on ISOLATION as an approach to chemical hazard control.

Isolation as a chemical control measure

The Hierarchy of Control is simply a sequence of 5-6 control measures, ranked in order from effective to least effective. When assessing a chemical hazard you systematically work your way through the sequence giving preference to the control measures at the top of the hierarchy.


Hierachy of Control

As a control measure, ISOLATION focuses on physically separating chemicals from workers (as well as from incompatible substances). Examples include:

  • Correctly segregating chemicals into compatible hazard classes

  • Separating chemicals using compliant safety cabinets or chemical stores

  • Locating chemical stores away from potentially hazardous activities — like anything that could ignite or fuel a fire

  • Minimising the number of workers who use or can physically access the chemicals

  • Using physical barriers to keep people away from the chemicals

IMPORTANT: Separating and segregating certain hazardous chemicals and Dangerous Goods is a requirement of some Australian Safety Standards (eg, Flammable Liquids, Compressed Gases). Always check Section 16 of the chemical’s Safety Data Sheet for relevant legislation, codes or practice and safety standards.

Isolating workers from hazardous chemicals

When hazardous chemicals are required by your business, the workplace can be made safer by minimising the amount of contact workers and other personnel have with the chemicals. Some effective examples include:

  • Placing laboratory chemicals in a fume hood or fume cabinet

  • Using closed or sealed systems for chemical dispensing and transfer

  • Carrying out certain mixing and experimental works in a glove box or glove bag

  • Restricting the amount of chemicals kept in work areas by storing them in safety cabinets or bulk stores constructed to Australian Safety Standards

  • Performing certain tasks in enclosures fitted with exhaust extractors that remove air-borne contaminants while the operator is working

  • Working from a positive pressure room which cannot be penetrated by air-borne contaminants

  • Restricting access to chemical storage and work areas

Segregating and separating chemicals

Hazardous chemicals should always be physically separated from incompatible materials and substances. This can be achieved by using physical barriers and creating safe working distances.

Isolating chemical stores

Where possible, chemical stores and handling areas should be strategically located away from key operations. In many cases isolating chemicals by distance only minimises the number of workers potentially exposed — there will still be people who actually handle the chemicals or transfer materials in and out of a chemical store.

Australian Safety Standards set separation distances for many chemicals, though you can expect your chemical stores should be at least 3-5 metres from:

  • Site boundaries and protected places (residences, places of worship, schools etc)

  • Combustibles, refuse, and vegetation

  • Ignition sources and industrial heat

  • Building openings (windows, doors, vents, ducting)

  • Other chemical stores, decanting and transfer stations

Segregating chemicals and Dangerous Goods

Chemicals should always be sorted into hazard classes eg, flammable liquids, compressed gases. Some incompatible chemicals must be completely isolated while others can be segregated within the chemical store eg, flammable, toxic and oxidising gases can be kept in the same chemical store provided they are segregated and kept at least 3 metres apart.

IMPORTANT: Empty and full chemical containers are usually stored separately and the empties clearly marked. Compressed gases in particular have specific requirements for their separation and storage.

Creating physical barriers

Apart from distance, some hazardous substances can be stored safely in the same chemical store if a physical barrier is created. This may be a fully contained chemical cabinet (eg corrosive cabinet made from polyethylene) or creating a screen wall inside the store.

Screen walls must be constructed from non-combustible materials and be impervious to the chemicals stored on either side. If you check the Safety Standards for the relevant substance you’ll find exact specifications.

Training staff in chemical storage and housekeeping

Control measures are almost worthless if managers and supervisors don’t implement them effectively. Eg, installing an under bench acid cabinet also means training lab staff not to leave acids and corrosives on bench tops. It requires proper training sessions, regular reviews, and consistent supervision.

EXAMPLE: Your workplace has purchased flammable liquids stores and placed them in strategic locations outside and away from manufacturing operations. These areas are now restricted to ‘Group A workers’. You’ll now want to ensure that:

  • Site plans are updated with the locations of the new flammable liquids stores

  • Operating procedures are developed and issued so all workers (especially Group A workers) understand the access restrictions

  • Staff are advised in updated Site Inductions, job specific training, and remedial training

  • Workers are supervised and provided with remedial training (or disciplinary action) if procedures aren’t followed.

Next Steps

For a more detailed discussion of the Hierarchy of Control and instructions for introducing a compliant risk management methodology, download our free eBook How to manage the risk of Hazardous Chemicals in the workplace. Read it today and get your workplace 100% chemical safety compliant.

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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