Activities Involving Highly Flammable Substances
Hazards:
Highly flammable substances including solids (e.g. dusts and plastic foams),
liquids (e.g. petroleum spirit and derivatives thereof) and gases (e.g. Hydrogen,
Methane) can be readily ignited and cause fires producing flame, heat corrosive
or toxic combustion products. Flammable vapours, gases and some dusts can
also cause combustive explosions with the additional hazard of flying fragments
or projectiles.
Risk Factors:
 The use of flammable substances in processes or manipulations in which
a flammable gas- or vapour-air mixture is formed (concentration of gas or
vapour) in air is within the flammable or explosive limits;
 The use of flammable materials of low ignition energy or autoignition
temperature;
 The use of liquids with flash point below ambient temperature or the use of
liquids at temperatures above their flash point;
 The use of any flammable gas, liquefied gas or liquid in open vessels or
apparatus in proximity to ignition sources such as flames, electrical
equipment and hot surfaces;
 The use of any flammable material in an oxygen-enriched atmosphere or
in contact with any oxidising agent;
 The use of and storage of gases and liquids in unventilated or poorly
ventilated locations;
 The use and storage of large amounts of flammable materials.
Persons at Special Risk:
Employees and others working with extremely flammable materials (e.g. Carbon
disulphide, acetylene, or oxy-acetylene equipment, compressed or liquid oxygen,
compressed hydrogen and spontaneously combustible pyrophoric materials).
Risk control Measures
1. Avoid the use of readily flammable or use substances which are unlikely
or difficult to ignite (e.g. use liquids of high flash point).
2. Contain flammable substances in apparatus or equipment which prevents
uncontrolled release, vaporisation and spillage.
3. Separate flammable substances from ignition sources by distance or the
use of fire-resisting cupboards, bins or apparatus.
4. Prevent the formation and accumulation of flammable gas- or vapour-air
mixtures and aerosols of flammable liquids by mechanical or natural
ventilation to dilute gases/vapours to 25% of the lower flammable or
explosive limit or use extract ventilation (e.g. a fume hood) to remove
gases/vapours from the work area to a safe place.
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5. Control sources of ignition so that they are separated from flammable
substances or flammable gas-vapour-air mixtures by distance or fireresisting material: or use electrical apparatus specifically designed for
hazardous area location.
6. Do not store or accumulate flammable dust deposits and other flammable
residues and wastes in the work room; do not store excessive quantities of
flammable materials in any work room and no more than 50Litres of highly
flammable liquid to be kept in closed containers within fire resisting
cupboard or bin.
7. Keep bulk quantities (e.g. containers of capacity greater than 2.5L
Winchesters) in a licensed petroleum spirit or a well-ventilated fireresisting store designed for highly flammable liquids separated from the
work room.
8. Provide suitable fire extinguishing equipment or systems (e.g. dry powder,
foam or carbon dioxide) in the work room and adjacent to each bulk store.
9. Do not permit the uncontrolled mixing of compressed oxygen or oxidising
agent with any flammable or combustible material unless adequate steps
have been taken to control the rate of mixing and ensuing chemical or
other reaction.
10. Keep cylinders of compressed oxygen free from grease, oils and
degreasing solvents and store away from cylinders of combustible gases.
Health Surveillance:
No special requirements
Exclusions:
This assessment may not be adequate for work with spontaneously combustible
substances or those which ignite on exposure to water; the use of highly
flammable liquids or petroleum spirit in apparatus of capacity greater than
5Litres; the use of any flammable gas in a pressure system where the product of
the pressure and volume exceeds 200bar Litres; the use of acetylene; work in a
zone 0 hazard area.
Relevant Statutory Provisions and Other Guidance:
Dangerous Substances and Explosive Atmosphere Regulations 2002 (DSEAR)
Highly Flammable Liquids and Liquefied Petroleum Gases Regulations 1972
Special Waste Regulations 1996
The storage of flammable Liquids in Containers, HSG51, 1998
Oxygen: fire and explosion hazards in the use of oxygen, HSE8
BS 5345 COP for the selection, installation and maintenance of electrical
apparatus for use in potentially explosive atmospheres, 1976
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