Safe use and storage of cellular plastics: Controlling the fire risk

Introduction

Cellular plastics (CP) include a wide range of polymers such as polyurethane (PU) and polyisocyanurate foams that are used in a wide range of applications. They are used mainly for upholstering furniture, packaging and insulation. Most are fire hazards and may be ignited easily with a small ignition source. Once established a fire can spread quickly often producing a large volume of thick, black, toxic smoke. The smoke can contain chemicals that are hazardous to people and the environment. Some types of plastic can continue to smoulder once the main fire has been extinguished giving off thick black smoke.

These pages give guidance to manufacturers, converters and users of CP on controlling the risk of fire.

General guidance on fire safety in the workplace can be found on the fire safety pages of the Gov.uk website.

HSE is responsible for enforcement of 'process' fire precautions eg fire hazards associated with particular processes. Local fire authorities are responsible for enforcing general fire precautions eg means of escape, layout of the building, fire alarm systems etc. Your local Fire Officer can also be a good source of advice on general fire precautions and design/layout of buildings. For further information on these areas of fire safety you should contact your local Fire Officer.

Please use the links below to find out more information about reducing the risks of using and storing CP.

Getting Started

When using and storing CP an assessment carried out under the Dangerous Substances and Explosive Atmosphere Regulations 2002 (DSEAR) should be completed to identify the package of controls that will be needed to reduce the risks. The DSEAR assessment should consider how to:

prevent fires starting;
restrict the rate of fire spread
ensure that in the event of fire everyone can escape safely
help fire brigades tackle any large fire; and
reduce the cost of a fire.

More information on completing a DSEAR assessment can be found here.

General safety

The following general safety points along with guidance on storage and processes can be used to reduce the risks of storing and working with CP.

Workrooms:

Keep just enough CP for processes in workrooms
Plan for processes that require large quantities of CP
Do not keep more that half a days supply in the workroom at any one time
Implement strict procedures for stacking, housekeeping and training of personnel

Housekeeping:

Keep work and storage areas clean and tidy
Do not allow dust from handling and cutting CP to accumulate on guards, machinery, electrical equipment and surfaces
Implement cleaning policies and procedures throughout the working day not just at the end of it.

Controlling Ignition Sources

One of the main ways to reduce the risks of fire when using CP is to control ignition sources. This includes ensuring other materials that can be easily ignited (eg loose paper) do not become an ignition source. Other ways to control ignition sources are below.

Naked flames should not be allowed in storage areas or workrooms unless in connection with a properly controlled manufacturing process such as flame-bonding;
Unavoidable hot work around CP, such as welding and cutting should only be carried out under strict controls. Permit-to-work systems may be appropriate.
Heating systems in CP storage areas should be chosen to reduce the risk of ignition. Portable direct gas or oil-fired heating appliances are not appropriate. Hot water systems or indirectly-fired hot-air systems may be used. If fixed solid fuel, gas or oil-fired heater units are used they should be located outside working area and stores.
Electrical equipment in CP areas should be considered in the DSEAR assessment to ensure the right type and standard is used. The assessment may consider but not be limited to:
- preventing accumulation of electrostatic charges eg earthing;
- prevention of CP dust or crumb contacting hot surfaces;
- protection required if there is likely to be an explosive atmosphere;
- preventing CP causing overheating by being pressed against electrical equipment;
- what British and/or European standards should apply to the required equipment.
Vehicles in workrooms and stores should be kept to a minimum. Hot parts of the engine and exhaust system can ignite CP. Electric vehicles are preferable and charging stations for batteries should be located away from CP areas.
Highly flammable liquids should be stored separately to CP.
Flammable gases such as pentane should be considered in the DSEAR assessment. The assessment should identify controls eg forced extraction at low levels, extraction during transport that will prevent a build-up of vapour igniting.
Machinery and plant should be properly maintained to eliminate ignition sources eg heat caused by friction or plant failure.
After work has finished check the workplace to ensure no sources of ignition have been left eg plant left on and that there are no signs of smouldering.