Firefighting

COURTESY  :  app.croneri.co.uk

Firefighting

Most fires start small but, if left to develop, they will grow and spread, causing a great deal of damage and threatening the lives of those in the vicinity.

In addition to the provision of portable fire extinguishers for controlling fires, organisations should consider the installation of fixed fire extinguisher systems to increase general fire protection facilities and/or to protect specific areas or equipment.

This topic outlines the various portable and fixed fire extinguishing systems that can be used in the event of a fire.

Employers’ Duties

The responsible/appropriate person or dutyholder will have duties under the relevant legislation, these being the:

• Regulatory Reform (Fire Safety) Order 2005
• Fire Safety (Employees’ Capabilities) Regulations 2010
• Fire Safety (Scotland) Regulations 2006
• Fire Safety (Scotland) Amendment Regulations 2010
• Fire (Scotland) Act 2005 (Relevant Premises) Regulations 2010
• Fire Safety Regulations (Northern Ireland) 2010.

Under the relevant legislation, the responsible/appropriate person or duty holder is required, where necessary (whether due to the features of the premises, the activity carried on there, any hazard present or any other relevant circumstances) and in order to safeguard the safety of persons, to ensure that the premises are equipped with appropriate fire-fighting equipment. Any non-automatic fire-fighting equipment provided must be easily accessible, simple to use and indicated by signs.

In addition, the responsible/appropriate person or duty holder must, where necessary, nominate competent persons to implement such measures and ensure that the number of such persons, their training and the equipment available to them are adequate. The size of, and the specific hazards involved in, the premises concerned must be taken into account.

Employees’ Duties

Under the relevant fire safety legislation, employees must co-operate with the responsible/appropriate person or duty holder to ensure the workplace is safe from fire and its effects, and must not do anything that will place themselves or other people at risk.

In Practice

Types of Fire-fighting Equipment

There are two types of fire-fighting equipment: portable (eg fire extinguishers, fire blankets) and fixed systems (eg fire hydrants, sprinkler systems).

Portable fire-fighting equipment

The function of a portable fire extinguisher is to deal with small fires that are detected soon after ignition. Fire-fighting equipment should be considered as a means of both prevention and protection. For example, portable fire-fighting equipment can prevent a small fire growing out of control and spreading beyond the area of origin, affecting the means of escape and posing a risk to relevant persons.

The provision of portable fire extinguishers should be as a result of a risk assessment and the requirements of BS 5306-8:2012 Fire Extinguishing Installations and Equipment on Premises. Selection and Positioning of Portable Fire Extinguishers. Code of Practice, which assumes that a fire risk assessment has been undertaken.

In simple premises, having one or two portable extinguishers of the appropriate type, readily available for use, may be all that is necessary. In more complex premises, a number of portable extinguishers may be required.

Choosing the right extinguisher

Portable fire extinguishers can be chosen according to the fire classification system set down in BS EN 2:1992 Classification of Fires, as illustrated in Table 1.

Fire Class	Typical Material Involved	Water	Foam (AFFF)	CO2 (Carbon Dioxide)	Dry Powder (ABC)	Special Powder	Wet Chemical
A	Wood, paper, cardboard, textiles, common plastics, foams	yes	yes	no	yes
B	Petrol, oils, adhesives, paints, varnishes	no	yes	yes	yes
C	Liquid petroleum gas (LPG), butane, methane, propane	yes	yes	yes	yes
D	Aluminium, magnesium, sodium, phosphorus	no	no	no		yes
F	Cooking oils and fats						yes
Electric	Electrical installations, computers, photocopiers, televisions, etc	no	no	yes	yes

Identification and labelling of portable extinguishers

Portable extinguishers should be labelled in accordance with the requirements of BS EN 3:1996 Portable Fire Extinguishers and BS 7863:2009 Recommendations for Colour Coding to Indicate the Extinguishing Media Contained in Portable Fire Extinguishers to indicate the extinguishing which implements it in the UK.

All extinguishers are coloured red, with identifying colours forming either part of the labels or as bands around the tops of the extinguishers. The main types of extinguisher are shown in Table 2.

Extinguisher Type	Colour Code
Water	Red with white label
Foam	Red with cream label
Carbon dioxide	Red with black label
Dry powder	Red with blue label
Aqueous film-forming foam (AFFF)	Red with cream label
Inert gas	Red with green label (these are not common)
Wet chemical	Red with yellow labels (these are not common and intended for use on cooking oil and fat fires)

BS EN 3 is not retrospective, and therefore extinguishers existing prior to 1996 do not have to be replaced but the advice of the service contractor should always be sought if there is any doubt as to whether the colour coding of different extinguishers might cause confusion, ie if extinguishers of different ages or manufacture are in the same working area.

Assessing the requirement for numbers and type of extinguishers

To realise the potential benefits of the provision and use of portable fire-fighting equipment, there are three distinct words or phrases that will drive the decision-making process.

1. Where necessary: in relation to the provision of appropriate fire-fighting measures and nomination of persons to implement them.
2. Appropriate: in relation to the type of fire-fighting equipment required.
3. Competent: in relation to the persons nominated to implement the fire-fighting measures.

The first consideration for the responsible person is therefore to decide if they require fire-fighting measures such as in the form of portable equipment. This is about determining what if any equipment should be provided to protect people or whether such provision is not necessary as it would not protect people and the cost of provision would be disproportionate to the risk.

The assessment of the need for the provision of fire extinguishers depends on the risk assessment — particularly the nature of the fire hazard(s) (class of fire) and the likely size of fire — and the effectiveness of a given type and size of extinguisher.

Consideration must also be given to the size of the premises and, in particular, that the nearest fire extinguisher should be no more than 30m away from the site of fire, as set out in BS 5306-8. This may be nearer for special risk fires.

The effectiveness of the extinguisher is given by its rating (assigned to effectiveness against class A or B fires, as appropriate) and to the volume of agent it contains. This then needs to be taken into consideration with the size of the premises and travel distances.

BS 5306-8 provides guidance on calculating the appropriate numbers of extinguishers.

Location of fire extinguishers

BS 5306-8 recommends that extinguishers should be:

• located so that no one has to travel more than 30 metres to reach one
• conspicuous, such as on escape routes, stairways, corridors, exits or landings
• grouped together in fire points, where practicable
• wall-mounted on brackets (not more than 1 metre high) and signposted
• easily accessible
• located in similar positions on each floor.

Additional extinguishers should be provided in close proximity to particular hazards.

Inspection and testing of extinguishers

Portable fire extinguishers must be maintained in an efficient working state, working order and good repair.

It is generally seen as good practice for all extinguishers to be subject to a monthly visual inspection by appropriate in-house staff members. In addition, there are four types of formal maintenance:

• basic service: an annual check
• extended service: either every 5 or 10 years
• recharge: after use or partial use
• overhaul: every 10 years on high pressure extinguishers.

Records of maintenance should be indelibly marked on durable label affixed to the extinguisher that does not obscure the instructions for use. This should provide details of the maintenance undertaken along with details of those undertaking the maintenance and any remedial action taken.

Maintenance as described above should be undertaken by a competent person (eg BAFE qualified).

Fire blankets

Fire blankets can be used to smother Class A and B fires, particularly in situations where burning clothing and small fires involving flammable liquids, such as cooking pan fire, are involved. Heavy duty blankets can be used for protection during hot work such as welding.

Blankets need to be provided and used with care. It is important that the user wraps the corner or edge of the blanket over their hands to protect them from the radiant heat of the fire, and that it is kept between the user and the fire to protect the user from the heat.

The blanket should be placed carefully over the burning container or wrapped around the person with burning clothes. If the fire is in a cooking pan, the heat should be turned off — if this can be achieved without placing the person using the blanket in any danger. The provision of fire blankets should follow from the risk assessment.

Except for smaller catering establishments, it is normally safer to use appropriate fire extinguishers (such as those designed for oil fires) than fire blankets.

Fire blankets should be designed to the requirements of BS EN 1869:1997 Fire Blankets.

Fixed systems

There are a number of fixed fire-fighting facilities available, including:

• fire hydrants and rising mains
• hose reel systems
• sprinkler systems
• water mist and fogging systems
• gas systems (sometimes referred to as “clean agent systems”)
• foam systems
• dry powder.

Fixed fire protection systems will usually be required/are advisable:

• where the usual requirements of the building regulations (with respect to means of escape or compartmentation) cannot be met due to reasons of practicability, or where a relaxation of those requirements is sought
• in high buildings, or buildings with deep basements, where fixed fire protection systems are required to assist the fire brigade in the protection of life
• in any building where the results of a fire risk assessment show that life safety may be compromised by an outbreak of fire that is not extinguished promptly
• in any building where it is necessary to provide compensation for some other fire precautionary measure that may be considered to require reinforcement, eg where it is not considered practicable to provide the required level of fire separation
• on the instructions of the insurers for the building (some insurers may be persuaded to offer a premium reduction for the installation of an approved system)
• where the consequential loss (loss of business, cost of replacement equipment, etc) from the effects of a serious fire would be very great.

Further information on the design, installation and use of fixed systems can be found in the following standards:

• BS EN 12094 series: Fixed Firefighting Systems. Components for Gas Extinguishing Systems
• BS EN 12259 series: Fixed Firefighting Systems. Components for Sprinkler and Water Spray Systems
• BS EN 15004 series: Fixed Firefighting Systems. Gas Extinguishing Systems
• BS EN 1568 series: Fire Extinguishing Media. Foam Concentrates
• BS 9990:2015 Non-automatic Fire-fighting Systems in Buildings. Code of Practice.

Fire hydrants

Fire hydrant systems are the means by which large quantities of water are distributed to premises (and within larger premises) so that the water can be used for fire-fighting purposes. It is normal for fire hydrant systems to be capable of delivering a virtually unlimited supply of water for use by the fire service.

In larger commercial and industrial premises, there is a requirement under building regulations for the installation of private fire hydrants for use by the fire service in the event of a fire.

The requirements for fire hydrants are contained in BS 9990:2015 Non-automatic Fire-fighting Systems in Buildings. Code of Practice.

Wet and Dry Risers

In buildings with large floor areas, and in high buildings, hydrant outlets will be required inside in order to overcome the difficulty which the fire service would otherwise have in conveying fire-fighting water to the seat of a fire. In these cases, the hydrants will take the form of landing valve outlets to which a standard fire service pattern hose can be connected. The landing valves will be mounted on wet or dry fire mains, usually referred to as “risers”.

Wet mains or risers are left charged and water is instantaneously available when needed. Dry risers are required to be charged, usually through an external coupling by the fire brigade when they attend the premises, to fight a fire.

Dry and wet risers need to be tested on a regular basis — usually annually — to ensure that they will operate as designed, that hose couplings are operational and that valves and wheel cocks are freely moving. It is the duty of the “responsible person” to ensure that these tests are undertaken.

The current British Standard used for design, installation, testing and maintenance of wet and dry risers is BS 9990:2015 Non-automatic Fire-fighting Systems in Buildings Code of Practice.

Hose reels

Hose reel systems are generally regarded as a first-aid fire-fighting measure intended for use by the occupants of the building. The fire service may also make use of them for small incidents. They are particularly useful for fire protection in buildings where there is a trained fire party or where contract works are frequently undertaken.

If specified, hose reels should be sited in prominent and accessible positions on each floor level and should preferably be adjacent to exits. Sufficient hose reels should be located so that the nozzle can be taken into any room and reach to within six metres of the furthest part of any room (so that the water jet from the nozzle can be brought to bear on any part of the room). There should be no areas of the floor level that cannot be reached by at least one hose reel.

The requirements for the provision of hose reels in most buildings are detailed in BS 5306-1:2006 Code of Practice for Fire Extinguishing Installations and Equipment on Premises. Hose Reels and Foam Inlets and BS EN 671-3:2009Fixed Firefighting Systems. Hose Systems. Maintenance of Hose Reels with Semi-rigid Hose and Hose Systems with Lay-flat Hose.

Sprinkler systems

Sprinkler systems are one of the oldest and most reliable methods of detecting and controlling fires automatically. They are primarily intended for property protection, but can have a role in life safety if they are specifically designed for that purpose and if they operate in conjunction with other fire safety provisions.

How a sprinkler system works

At its most basic level, a sprinkler system consists of a network of pipes connected to a water supply via a main valve. The network extends throughout the whole of the area to be protected, with sprinkler heads (the detection devices) evenly spaced to cover the whole area. The sprinkler heads are always heat operated and are set to detect a small but established fire. When a fire is detected, the head which has detected the fire opens and allows water to flow. The head is designed in such a way that the flow of water is broken up into a spray and falls like heavy rain on the area under the head, the flow of water also causes an alarm to be sounded.

Contrary to popular belief, only heads directly affected by heat will allow water to flow. On almost all occasions only the one or two heads directly over the area of the fire will operate. These will usually be sufficient to control the fire and often extinguish it completely. The flow of water applied through each head is strictly controlled by design — the quantity being varied depending on the risk to be protected. Because heads only operate in the presence of a small fire, sprinkler systems very rarely cause unnecessary water damage.

Types of sprinkler system

Sprinkler systems from different manufacturers (in the UK) are all very similar, as they are all designed to meet Loss Prevention Council (LPC) rules (now available from BRE Certification) and also BS 5306 Fire Extinguishing Installations and Equipment on Premises. However, there are some different types of system depending on the nature of the risk to be protected.

• Wet Pipe System: all the pipework is kept permanently full of water, right up to the sprinkler head. This type of system is standard in most buildings, and has the fastest response in terms of applying water to a fire. It should not be used in areas where there is a risk of freezing temperatures.
• Dry Pipe (Pre-action) System: intended for use in cold stores or similar premises where the temperatures are maintained below or close to the freezing point of water. The pipework is kept charged with compressed air to hold the water back below the control valve.
• Alternate System: used where temperatures vary seasonally. The system is kept “wet” during the summer period for the fastest response, and “dry”, ie charged with compressed air, during the winter to avoid freezing.
• Pre-action System: used in areas where the consequences of accidental discharge, due to mechanical damage, are considered unacceptable, eg rooms containing electronic data processing or electrical equipment.
• Deluge Systems: used to protect certain special risks, where there is a possibility that an intense fire will develop very rapidly, eg oil-filled transformer equipment. Deluge systems (sometimes also called “fogging” or “drencher” systems) are usually used to protect relatively small, external risks.

Water mist systems

Water mist systems have been developed with the aim of extinguishing fires using the absolute minimum amount of water.

The key to the success of water mist is ability of small water droplets to suppress or control a fire extremely efficiently. A traditional sprinkler system removes the heat element of the triangle while water mist removes both the heat and oxygen elements of the triangle. It achieves this by dispersing water through specially designed nozzles at low, medium or high pressure. Generally, as system pressure increases, the water droplet size decreases. This, in turn, significantly increases the total surface area of the unit and so leads to production of a greater volume of steam, removing more energy from the fire, which generates the steam.

Further information can be found in BS 8489-1:2016 Fixed Fire Protection Systems. Industrial and Commercial Watermist Systems. Code of Practice for Design and Installation.

Water fog systems

High pressure water spray projector systems, primarily designed for the protection of oil filled transformers, are sometimes referred to as water fog systems. However, these are actually drencher systems and should be designed in accordance with rules governed by the conventional sprinkler technology on which they are based.

Gaseous systems

Gaseous fire extinguishing systems work by replacing the normal atmospheric gases, which support combustion, with a gas, or mixture of gases which do not support combustion. These are sometimes also referred to as “clean agent” systems, as they do little or no damage to the property around them in comparison to water or foam.

Gaseous extinguishing media have been used for a long time to protect specialised applications, such as computer suites, control rooms and areas with critical electrical equipment, or are used to protect electronic data processing equipment. These systems are generally automatic and linked to detectors causing the gaseous agent to be released when fire is detected. They rely upon the gas being contained in the fire compartment to ensure that sufficient concentration of the agent is available to effectively extinguish the fire. Rooms therefore need to be sealed and have controlled ventilation.

Foam systems

Foam systems are mainly used for the protection of large flammable liquid risks, such as oil storage tanks. Foam may be applied in two ways.

1. Self-contained systems: these have their own foam and consist of foam-making equipment, foam supplies and pipes connected to outlets. They may be designed to operate automatically by the incorporation of detection systems, and may also give an alarm.
2. Systems to which the fire brigade connect foam-making equipment: in these systems, the foam-making equipment is replaced by an inlet sited on the outside of the premises at street level.

Low expansion foam is suitable for flammable liquid fires where the liquid is immiscible (ie does not mix) with water. The rate of application of the foaming solution per unit area determines the time required to control and extinguish the fire. Low expansion foam has good water retention, heat resistance and gives long-term stability, but does have limited volume and fill capability.

High and medium expansion foam is made by the aeration of an aqueous solution of a synthetic foaming agent to the appropriate expansion. Medium foam is used for “low level” applications where a blanket formation is required, while high expansion foam is used when a volume performance is required (eg in basements or cable tunnels).

High expansion foam is typically used in confined spaces, eg in some warehouses, tunnels, aircraft hangers and in some specialist applications involving flammable gases.

Dry powder

In these systems, the powder is kept in a pressurised container or is connected to a gas cylinder with a system of pipework leading to outlets. Dry powder systems are used to extinguish fires in:

• solid combustibles
• flammable liquids
• gases
• flammable metals.

Dry powders need suitable flow and anti-caking additives in fixed systems. Although not normally toxic, they can cause loss of visibility and breathing difficulties. Therefore, evacuation of the protected area is desirable before the system is activated.

Dry powders should not be used for electronic protection or tightly-packed combustibles such as record vaults.

Testing, Inspection and Maintenance of Fixed Systems

BS 9999:2017 Code of Practice for Fire Safety in the Design, Management and Use of Buildings, states that “planned inspection, maintenance and testing procedures should be established and used to ensure that all fire protection systems can operate effectively when required. Arrangements should be made for all fire safety equipment, installations and systems to be inspected and tested on a regular basis by a competent person”.

Where fixed systems are installed, the duty holder should establish an appropriate regime for testing, inspection and maintenance. This will usually be through reference to national standards as detailed in this topic.

Further details can be found in the accompanying forms and templates for this topic.