M/L5 Automatic fire detectors are
sited in such a way as to compensate for the lower standard in other fire precautions. Buildings with "inner rooms", from which escape is possible only by passing through another ("access") room, where there is inadequate vision between the inner room and the access room.
M/L5 Smoke detectors are sited in
the access room.
Buildings in which automatic fire detection is required to operate other fire protection systems (eg magnetic door holders).
M/L5 Care is necessary to ensure that automatic fire detectors are sited such that cool smoke cannot pass below the level of the detectors that cause the release of the magnetic door holders and through the (still open) doors. Situations in which fire could readily spread from an unoccupied area and prejudice means of escape from occupied areas.
M/L4 or M/L5 Custom and practice does
not involve sitting automatic fire detectors in all unoccupied areas, such as plant rooms and storage areas. Any building in which automatic fire detection is provided as a requirement of a property insurer or to attract an insurance premium discount.
M/P1 or M/P2 -
Ref. BRADFORD FIRE PREVENTION GROUP
Type M systems encompass all manually-activated fire systems. Type M (Manual: Life Protection) This is the basic and minimum requirement needed in all premises. It provides the facility for manual operation of call points and depends on the presence of people to activate the system. Call points are typified by break glass switch.
2.5 Fire Alarm Zoning To ensure accurate and expedient identification of the fire source, areas should be divided into zones. When determining the area to be covered by a zone, consideration should be given to accessibility, size, the fire routine determined for the premises and - particularly in occupied premises - that each zone is accessible from the main circulation routes leading from where the control panel is sited. Basic guidelines for the size of the zone should be observed:
• If the total area of the building (i.e. the total of the floor areas of each floor) is not greater than 300m2, then the building need only be one zone, no matter how many floors it has.
• The total floor area of a zone should not exceed 2000m2.
• The search distance should not exceed 30m. The use of remote indicator lamps outside doors may reduce the number of zones required.
• If the zone covers more than one fire compartment, then the zone boundaries should follow compartment boundaries.
• If the building is split into several occupancies, no zone should be split between two occupancies.
• If the detector in a zone becomes faulty or inoperable, it must not prevent the operation of detectors in the remaining zones. A single fault should not remove protection from an area greater than that allowed for a single zone.
2.6 Alarm Signalling The notification that a detection system has been activated falls into two principal headings, aural and visual. Both types tend to be used in combination with each other.
As detailed in the section regarding disabled persons, each type is of specific use to certain groups of people. Visual systems such as a strobe light should also be used in areas of high noise, perhaps when ear protection is used. It should be noted that audio systems have specified sound (or pressure) levels that are audible even in conditions of high noise.
Recent technology introduces tactile devices, such as radio alarm systems that are ideal for people working in isolation, or for deaf people. The system consists of two parts - a transmitter linked into the fire alarm control panel and a receiver which is a vibrating pager. When the fire alarm is activated, it automatically and immediately switches on the radio transmitter that sends a digitally-encoded radio signal to each more alert in the building. The more alert vibrates and displays the text fire message. Such systems are referred to in
BS5839.
2.7 Use of alarm receiving centers Both automatic and manual fire detection systems can be connected to an alarm receiving center; this connection is normally via a telephone line.
The use of such a monitoring system can provide significant benefits.
Such a system provides constant monitoring of the fire detection system, constant meaning 24 hours a day, 7 days a week. The majority of fires start after normal working hours, and a long period of time could elapse before the fire was detected if the building was unoccupied.
In an evacuation, when the principal objective is to get everyone out of the building, the need to call the fire and emergency services can sometimes be overlooked. The person nominated to call the fire and emergency services might be unavailable or, worse still could be trapped by the fire.
Alarm receiving centers also provide the facility to contact the emergency services. They will also call a named person, typically a nominated key holder or premises owner.
3.0 Factors to be considered in the selection of fire detection and fire alarm systems As detailed in previous sections (Categories of fire alarm and detection systems), there are two principal reasons for installing a fire detection and alarm system; these are the protection of life and the protection of property. Each needs separate consideration for a system's design and selection of appropriate equipment. In the majority of premises, there is a need for both life and property protection in differing degrees.
Fire risk assessment should be relied upon to arrive at the optimum balance of life and property risk. Such a conclusion cannot be reached accurately in an arbitrary manner.
The prevention of loss of life should always take precedence, but as a view of property risk, a good example would be a warehouse with high-value stock which only needed to be operated by a small number of people, added to which the design of the warehouse provided good passive protection and means of escape. The ‘shift’ towards the system to protect property is obvious.
The opposite of this situation would be the scenario of a cinema or theatre; the building and assets would be of great financial value, but the prevention of injury or loss of life to the occupants would be the overriding factor.
The sample scenarios in the previous paragraphs can be used to demonstrate the different factors to be taken into account in the selection of detection and alarm system, as each scenario has separate requirements.
We can see that the types of premises and the classifications of detection are already established:
sited in such a way as to compensate for the lower standard in other fire precautions. Buildings with "inner rooms", from which escape is possible only by passing through another ("access") room, where there is inadequate vision between the inner room and the access room.
M/L5 Smoke detectors are sited in
the access room.
Buildings in which automatic fire detection is required to operate other fire protection systems (eg magnetic door holders).
M/L5 Care is necessary to ensure that automatic fire detectors are sited such that cool smoke cannot pass below the level of the detectors that cause the release of the magnetic door holders and through the (still open) doors. Situations in which fire could readily spread from an unoccupied area and prejudice means of escape from occupied areas.
M/L4 or M/L5 Custom and practice does
not involve sitting automatic fire detectors in all unoccupied areas, such as plant rooms and storage areas. Any building in which automatic fire detection is provided as a requirement of a property insurer or to attract an insurance premium discount.
M/P1 or M/P2 -
Ref. BRADFORD FIRE PREVENTION GROUP
Type M systems encompass all manually-activated fire systems. Type M (Manual: Life Protection) This is the basic and minimum requirement needed in all premises. It provides the facility for manual operation of call points and depends on the presence of people to activate the system. Call points are typified by break glass switch.
2.5 Fire Alarm Zoning To ensure accurate and expedient identification of the fire source, areas should be divided into zones. When determining the area to be covered by a zone, consideration should be given to accessibility, size, the fire routine determined for the premises and - particularly in occupied premises - that each zone is accessible from the main circulation routes leading from where the control panel is sited. Basic guidelines for the size of the zone should be observed:
• If the total area of the building (i.e. the total of the floor areas of each floor) is not greater than 300m2, then the building need only be one zone, no matter how many floors it has.
• The total floor area of a zone should not exceed 2000m2.
• The search distance should not exceed 30m. The use of remote indicator lamps outside doors may reduce the number of zones required.
• If the zone covers more than one fire compartment, then the zone boundaries should follow compartment boundaries.
• If the building is split into several occupancies, no zone should be split between two occupancies.
• If the detector in a zone becomes faulty or inoperable, it must not prevent the operation of detectors in the remaining zones. A single fault should not remove protection from an area greater than that allowed for a single zone.
2.6 Alarm Signalling The notification that a detection system has been activated falls into two principal headings, aural and visual. Both types tend to be used in combination with each other.
As detailed in the section regarding disabled persons, each type is of specific use to certain groups of people. Visual systems such as a strobe light should also be used in areas of high noise, perhaps when ear protection is used. It should be noted that audio systems have specified sound (or pressure) levels that are audible even in conditions of high noise.
Recent technology introduces tactile devices, such as radio alarm systems that are ideal for people working in isolation, or for deaf people. The system consists of two parts - a transmitter linked into the fire alarm control panel and a receiver which is a vibrating pager. When the fire alarm is activated, it automatically and immediately switches on the radio transmitter that sends a digitally-encoded radio signal to each more alert in the building. The more alert vibrates and displays the text fire message. Such systems are referred to in
BS5839.
2.7 Use of alarm receiving centers Both automatic and manual fire detection systems can be connected to an alarm receiving center; this connection is normally via a telephone line.
The use of such a monitoring system can provide significant benefits.
Such a system provides constant monitoring of the fire detection system, constant meaning 24 hours a day, 7 days a week. The majority of fires start after normal working hours, and a long period of time could elapse before the fire was detected if the building was unoccupied.
In an evacuation, when the principal objective is to get everyone out of the building, the need to call the fire and emergency services can sometimes be overlooked. The person nominated to call the fire and emergency services might be unavailable or, worse still could be trapped by the fire.
Alarm receiving centers also provide the facility to contact the emergency services. They will also call a named person, typically a nominated key holder or premises owner.
3.0 Factors to be considered in the selection of fire detection and fire alarm systems As detailed in previous sections (Categories of fire alarm and detection systems), there are two principal reasons for installing a fire detection and alarm system; these are the protection of life and the protection of property. Each needs separate consideration for a system's design and selection of appropriate equipment. In the majority of premises, there is a need for both life and property protection in differing degrees.
Fire risk assessment should be relied upon to arrive at the optimum balance of life and property risk. Such a conclusion cannot be reached accurately in an arbitrary manner.
The prevention of loss of life should always take precedence, but as a view of property risk, a good example would be a warehouse with high-value stock which only needed to be operated by a small number of people, added to which the design of the warehouse provided good passive protection and means of escape. The ‘shift’ towards the system to protect property is obvious.
The opposite of this situation would be the scenario of a cinema or theatre; the building and assets would be of great financial value, but the prevention of injury or loss of life to the occupants would be the overriding factor.
The sample scenarios in the previous paragraphs can be used to demonstrate the different factors to be taken into account in the selection of detection and alarm system, as each scenario has separate requirements.
We can see that the types of premises and the classifications of detection are already established:
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