Samuel Nii Tettey (Ergonomist)

At the end of Session, participants should be able to: - Identify fire problems at the enterprise level and Conduct Fire Risk Assessment Suggest remedial measures

Fire is essential for a number of activities including: -  Cooking  Clearing of bush for farming  Disposal of waste materials  Welding  etc

 Fire is a manifestation of uncontrolled combustion.  It involves combustible materials which may be present in any of the three physical states of solid (wood, wood products, polymers, etc), liquid (kerosene, petrol, etc) and gas (liquefied petroleum gas – LPG, propane, butane, etc.).

Combustible materials are commonly referred to as fuels and in spite of their chemical or physical nature, in fire they share common features – for example, they all emit heat energy or both heat and light.

Differences in fuels are determined by  i. the manner in which fire in the different fuels is initiated (ignition),  ii. the rate of development of the fire (flame spread) and  iii. the energy generated i.e. the rate of heat release.

This may be considered from the  Physical point of view; and  Chemical point

 The heating of a fuel surface results in the release of vapour ‘fuel’ which mixes with an oxidizing agent (e.g. oxygen or fluoride) to form a flammable mixture  The mixture may be ignited when it comes into contact with an ignition source.  A fire will occur if the rate at which the fuel vapours is being generated is sufficient to support the flame after the vapour has been ignited.

 Liquid fuels are classified according to their flash point i.e. the lowest temperature at which there is a flammable vapour/air mixture at the surface of the liquid.  At this point the vapour pressure is correspondent to the lower flammability limit.

 The fuel combines with the oxidising agent in an exothermic reaction.  The products of combustion are compounds in the fuel as well as the oxidizing agent.  Methane, for example, burns in oxygen resulting in the formation of water and carbon dioxide.

CH 4 + 2O 2 → CO 2 + 2H 2 O CH 2 S + 6F 2 → CF 4 + 2HF + SF 6 Hydrogen burning in Oxygen 2H 2 + O=2H 2 O(g) + heat

The oxygen is normally derived from the ambient air and the resultant flue gases contain nitrogen  CH 4 + 2O N 2 → CO 2 + 2H 2 O N 2 + heat

 Combustion processes are not always complete.  For example, when carbonaceous materials (wood, coal, hydrocarbons, etc.) are burnt the resultant flue gases may contain unburnt carbon (in the form of soot) and other carbon compounds as well as nitrogen oxides (NO 2 ), especially when ambient air is the oxidant. In the case where combustion is not complete)

 Fuel  Ignition source  Oxygen

Fuel Ignition Source Oxygen Chemical Reaction

 these three elements – fuel, ignition source, oxygen- must be present in their rightful quantities simultaneously for fire to occur

Combustion may may be classified as: -  Rapid  Slow  Incomplete  Complete  Smouldering

 In rapid combustion heat and light energy are released which may be accompanied large volume of gas.  This sudden evolution of large amounts of gas creates excessive pressure producing a large noise.  In this case the combustion is an explosion.

 Education  Management’s support  Operating Standards  Use of latest Training Materials  Appropriate Legislation (national) aimed at preventive strategies

 Major Enterprise Level Policy  Development of Effective Plan  Planning Phase - Goals & Objectives  Design & Implementation Phase  Monitoring & Evaluation

 Goals – General statements of intent. E.g. “To reduce number of fires and thus reduce fire-related deaths and injury among workers and financial impact on the Company”

Should be: -  Specific  Measurable  Achievable  Realistic  Time bound

 “To reduce workplace fire accidents by 50% by December 2006  “To reduce fire accidents by 90% by Mid-July 2007”  “Reduce Company property damage through fire by 40% by end June 2007”

 Minimize fire accidents through effective fire prevention programmes  Provide effective means to limit the size and consequences of fire incidents thro’ an effective emergency programme

 Development of well-planned strategies  Effective management  Motivation  Strong & absolute management support

 Promotion of policy on fire safety  Identification of all potential fire scenarios and implementation of risk reduction strategies  Training of employees in fire prevention & & emergency response techniques  Monitoring compliance with national legislation  Operating s loss administration programme that assures comparison with performance objectives

Good housekeeping ensures minimisation of combustible loads and prevents exposure of ignition sources

 Good housekeeping does not mean “a place for everything and every thing in its place” but ensuring that flammable materials are kept away from ignition sources  Ensuring that combustible waste are properly disposed of

 Ovens  Kilns  Furnaces  Dehydrators  Dryers  Quench Tanks

 Ignition of combustible material stored nearby  Incomplete combustion resulting in fuel mixing with oxygen to form an explosive mixture  Overheating of equipment  Ignition of materials being processed

 Good Housekeeping  Proper work systems – Permit to work system  Operator training & Testing  Cleaning and Maintenance in an effective fire prevention programme