Food and Drink Fire Safety Risks |
5.1 Introduction: When conducting a fire risk assessment it will be necessary to take into account the overall fire load in the premises and sources of ignition in relation to the distribution of fire load. Some specific areas of fire risk are considered in the section together with appropriate loss control measures.
5.2 Food heating and cooking equipment
5.2.1 Siting of cooking and food heating equipment: Where the risk assessment concludes that this equipment presents a high risk of fire it should be located in designated areas separated from other areas by a fire resisting structure including ceilings (and floors where applicable).
The level of fire resistance will depend upon the type of fire risk. For example, deep fat fryers should be separated from the rest of the factory by an enclosure within a minimum of 60 minutes fire resistance. (Where automatic fixed firefighting systems are installed for other types of fryers or ovens a reduction in the fire resistance may be possible.
5.2.2 Heated storage and transfer lines: Where heat is employed to keep fats, oils and the like the risk of fire in these areas should be assessed. The same considerations noted in 5.2.1 apply.
5.2.3 Fixed fire suppression equipment: Specific high fire risk areas, particularly deep fat fryers, should be protected by fixed fire suppression systems. Automatic systems are to be preferred over manual systems. Conventional water sprinklers may not be suitable and specially designed foam, fog, powder or gas systems may be needed.
5.2.3.1 Installation and maintenance: It is preferable that systems be designed and installed by an LPCB certificated firm complying with LPS 1204.
5.2.4 Fume extraction ductwork: Where fume extraction is used on high temperature processes the temperature and nature of the effluent should be considered. Where fat or grease is likely to condense in the ducts the route taken should be as short as possible and be designed to minimise horizontal runs. A sufficient number of inspection hatches should be provided to allow thorough inspection and cleaning.
5.2.4.1 Ductwork carrying hot gases: Hot ductwork should not be allowed to come into contact with combustible materials.This is particularly important where hot ductd pass through partitions,ceilings or roofs. The hot exhaust from duct outlets should be able to disperse safely and should not come into contact with combustible roof or wall elements.
5.2.4.2 Cleaning of fume extraction ductwork: Deposits of fat, grease or combustible dust should not be allowed to accumulate. A regular cleaning schedule should be set up. The cleaning should include traps and filters and care should be taken to ensure that the operating mechanisms of any fire dampers installed are also clean and free to operate. Further guidance is given in Health and Safety Executive (HSE) Guidance documents
HS(G)55 – Health and Safety in Kitchens and Food
Preparation Areas and LPC RC16B.
5.2.4.3 Fire detection and suppression: Hot fume extraction systems pose a high fire risk and the provision of automatic fire suppression systems within the ductwork should be considered.
5.2.4.4 Hot work on fume extraction ductwork: The ducting should be cleaned before any maintenance involving hot work is undertaken on the system and wherever possible the ductwork should be removed to a workshop where hot working has been declared safe.
5.2.5 Flues from heating appliances: Flues from heating appliances will contain hot gases and the same requirements as those for ductwork in clause 5.2.4.1. apply. Regular cleaning and maintenance is also necessary.
5.2.6 Housekeeping: Areas around high temperature equipment should be kept clean and free of combustible material and debris and should not be used for storage. Oil or fat spills should be cleaned up immediately with suitable water-based detergents or non-flammable solvents. Any used cleaning materials such as cloths contaminated with oil, should be disposed of immediately in a covered non-combustible bin and removed from the building daily.
5.2.7 Thermal cut-out devices and liquid level controls: All heating and cooking equipment devices should operate at a temperature appropriate to the process and not have an excessive margin above the normal working temperature of the equipment. For example, deep fat fryers should have thermal cut-outs below the flash point of the cooking medium (about 230 degreesC for normal cooking oils). Thermal cut-out devices should not have automatic resetting. For deep fat frying, devices should be fitted to monitor the liquid level and give warning of over of under filling. These should be linked to a heat cut-off device if the risk assessment indicates that this is necessary. Fuel supplies should be turned off when equipment is not in use.
Where oils are stored in fixed tanks the pipework supplying the oil to the process plant should indicate a clearly identified emergency cut-off valve external to the process building. Where practical such valves should operate automatically.
5.2.8 Maintenance: All cooking and food heating equipment should be regularly and properly maintained. Particular attention should be paid to emergency cut-off valves and mechanisms for protection from over heating which should be kept clean and in good working order. Heat sensors and fusible links connected to automatic fire suppression systems should be kept clean and unobstructed.
5.3 Bulk packaging materials
5.3.1 Introduction: Most food products will require some form of packaging. Virtually all packaging materials are inherently combustible and are often kept in large quantities in food processing buildings.
5.3.2 Storage: It will be necessary to control the amount of stored packaging material at risk. For bulk storage of packaging this may be done by segregating the stored material from the production areas. Segregation can be achieved by using separate fire resisting compartments or detached buildings. An alternative strategy is to limit the amount of material on site by using, for example, “just-in-time” supply methods.
5.3.3 Packaging process: In the areas where products are packaged the amount of packaging material should be kept to the minimum required for day to day operation. Particular care is needed where the packaging process involves heat, such as in shrink wrapping. The LPC Recommendation RC17 on shrink wrapping give advice on this.
5.3.4 Protection: Consideration should be given to automatic sprinkler protection for bulk packaging stores and packaging manufacturing areas.
5.4. Control of combustible waste
5.4.1 Introduction: Combustible waste should not be allowed to accumulate in work areas or stores.
5.4.2 Storage and disposal: If possible, combustible waste should be removed from premises on a daily basis. Where this is not practical such waste should be kept in one of the following until removed from the site:
· A completely enclosed and preferably lockable skip, bulk bin or compactor well clear of buildings i.e. at least 10m
· A detached non-combustible building well away from other buildings i.e. at least 10m.
· A room separated from the rest of the process or storage building by a fire resisting construction with a minimum of 60 minutes fire resistance.
· An external enclosure well away (i.e. at least 10m) from site buildings and the site boundary. Such an enclosure should have a roof or similar covering to prevent waste blowing away.
5.4.3 Security: Combustible waste storage areas should be secure. The level of security (i.e. the types of locks, fences, door and the like) will depend upon the assessment of the risk of arson for the site.
5.4.4 Used oil and fats: These should be segregated from other combustible waste.
5.4.5 Disposal by burning: The disposal of combustible waste by burning on site should not be carried out unless a purpose built incinerator is used. Such equipment should be sited in a suitable place, properly installed and maintained according to the manufacturers instructions. If incineration of waste is to be considered the local authority should be consulted as a license may be required.
5.5 Bulk storage of cooking medi-oils,fats
5.5.1 Introduction: Oils and fats are combustible materials, that, although not readily ignited at normal room temperatures, will make a significant contribution to the spread of an established fire. When at temperatures used for cooking these materials are more readily ignited. As these substances are liquid or become liquid when they burn they are a greater hazard than solid combustible materials such as paper. Unsaturated vegetable oils may be subject to spontaneous heating if dispersed on an absorbent medium such as a cloth or paper and exposed to air.
5.5.2 Storage: New oils and fats should be kept in either a detached non-combustible building or a room separated from the rest of the building by a fire resisting construction with a minimum of 60 minutes fire resistance.
5.5.3 Containment of leaks and spills: Areas where oils and fats are stored should have some means of containing liquid in the event of spills, leaks or fire. Bunds, sills or trays should be used as appropriate to the volume stored. Sills and bunds should be designed to contain at least 110per cent of the volume of the largest single container expected in the containment area whether a drum or a fixed tank.
5.5.4 Housekeeping: All spills or leaks in storage areas should be cleared up immediately. Small amounts may be removed with suitable water-based detergents. Larger amounts may be removed by absorbing on special porous materials. When absorbed in this way the material should be removed immediately to a non-combustible covered container and stored in the open away from any combustible items or structures.
5.6 Refrigerant gases: These gases may be flammable and, if so, there is a risk of explosion if leaks occur. Ammonia is flammable and where used as a refrigerant the recommendations of HSE guidance note PM81 should be followed. This gives guidance on management, selection, installation, operation and maintenance of refrigeration plant using ammonia.
5.7 Heat transfer systems: Where thermal fluid heating systems are installed the LPC Recommendations RC26 Organic Thermal Fluid Heating Systems should be followed.
5.8 Insulated composite panels(sandwich panels)in existing buildings
5.8.1 Introduction: Traditional building elements such as those made of brick, concrete, timber, steel and plaster do not make a significant contribution to the fire load when compared with the contents of most industrial premises. Where insulated composite panels form part of the building structure there may be a very significant fire load in the insulation material within the panels and this should be minimised wherever possible. This is particularly important where such panels are used for internal structures such as partitions and ceilings which, through their combustion, may add significantly to the production of heat , smoke and toxic products within the building. (The behaviour of sandwich panels exposed to fire is discussed in more detail by G.M.E. Cooke in Building Engineer, July 1997 – Ref 1, Appendix 1.)
5.8.2 Type of insulation material: The composition of the insulation material should be identified. This should be done from purchasing records or examination of spare panels if possible. Damaging the outer skin of similar panels to obtain samples should be avoided.
5.8.3 Relationship to the risk assessment: The following fire risk Factors should be considered, as part of the risk assessment, with respect to insulated composite panels.
5.8.3.1 The fire load: The insulation within composite panels may make a significant contribution to the fire load and should be included in the assessment.
5.8.3.2 Ease of ignition: The ease with which the insulating core will ignite both when enclosed within the panel and when exposed through damage to the outer skin needs to be determined.
5.8.3.3 Speed of fire spread: The rate at which the insulation in the core burns will indicate what contribution it will make to the speed of fire spread. This will depend to some extent on the nature of the jointing of the panel faces and the method of fixing.
5.8.3.4 Production of smoke and toxic products: Combustible cores in internal walls and ceiling composite panels are likely to produce considerable Amounts of smoke which, depending on the nature and jointing of the panel faces, may spread to other parts of the building adding to the fire loss. Large volumes of smoke may also have detrimental effects on the external environment.
5.8.3.5 Susceptibility to mechanical damage: The “toughness” of the outer skin of a panel will indicate how readily a combustible core may become exposed through mechanical damage. The resistance of panels to impact damage is Therefore an important factor. In particular their Resistance to delamination when used as Walkways above enclosures should be considered.
5.8.3.6 Fire resistance of panel assemblies: This is important where the risk assessment shows the need for a fire resisting enclosure. See clause 9.3.3.
The information required to make the risk assessment should be available from the panel manufacturer. If the relevant information is not available Table 1 gives an approximate indication of some of the relevant factors for metal faced composite panels currently in use.
5.8.4 Results of the risk assessment: Where the risk assessment shows the existing panels to be incompatible with the fire risk the following options are recommended.
i Relocate high risk operations to more suitable area
ii Replace the panels with ones certified to be the appropriate fire resistance or low combustibility, for example by complying with LPS 1208.
TABLE 1. The numbers give an approximate comparison of the
Performance of each type of panel(1 is the best performance, 5 is the worst).
|
CORE TYPE |
FIRE LOAD Note 1 |
EASE OF IGNITION |
FIRE SPREAD |
FIRE RESISTANCE Note 2 |
THERMAL INSULATION Note 3 |
SMOKE PRODUCTION Note 4 |
|
Expanded Polystyrene |
5 |
5 |
5 |
5 |
2 |
5 |
|
Polyurethane Foam |
5 |
5 |
3 |
5 |
1 |
4 |
|
Polyisocyanurate Foam |
5 |
3 |
3 |
4 |
1 |
4 |
|
Modified Phenolic foam |
5 |
2 |
3 |
3 |
? |
3 |
|
Glass Foam |
1 |
1 |
1 |
1 |
? |
1 |
|
Mineral wood |
1 |
1 |
1 |
1 |
3 |
1 |
Notes:
1. These comparisons are based on current designs and construction. Developments in design, particularly joint construction, may lead to improved fire performance.
2. Fire resistance is measured for a complete construction, including the supporting structure and joint detail. Even core types rated 1 for the fire resistance above will only achieve that if properly constructed and installed.
3. Thermal insulation in this table refers to the thermal insulation provided by the panel during normal use and not to the insulation value under fire conditions as defined in 3.3.1. The values given are intended as a guide to the relative insulation properties of the different cores. In practice, equivalent insulation performances may be obtained by increasing or decreasing the thickness of the core.
5.8.6 Specifying for new buildings or major refurbishments and extensions: When a new building or a major refurbishment is being planned the recommendations of the LPC Design Guide for the Fire Protection of Buildings should be adopted. Particular reference should be made to Part 7.2 which deals specifically food factories.
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