Twinflex Fire Alarm Panels

The advantages of a two wire system dramatically reduces installation times and costs in addition to reducing the overall disruption to a buildings fabric. Over and above this the twinflex devices (multiopoint detectors and detector sounders) can be configured to have 16 different modes of operation, including both smoke and heat detection. Meaning that once the points for detection and alarm have been identified the same multipoint devices can be used throughout.

Fire Alarm Zones

Twinflex 2 zone panel

In a HMO it is crucial that when the fire alarm is triggered and the fire service attend they can quickly identify the source of the fire and react accordingly. This is one of the main reasons for separating a fire alarm system into different zones. The number of zones required is stipulated by a fire risk assessment for that particular building but BS5839-6 also stipulates the maximum floor area allowed per zone and the minimum number of zones by floor area. For instance in a building with an area of less than 300m² a single zone system can be installed regardless of the number of floors, although this will depend on the risk assessment.

In a building with a floor area above 300m² it is necessary to install a system with multiple zones. The maximum area for each zone is 2000m² and stairwells go beyond a single floor they must be designated a separate zone.  Zones cannot be shared between different occupiers of a property and zone boundaries should follow fire compartment boundaries. Finally the distance required to search for the location of a fire shouldn’t go beyond 30m.

2 zone twinflex panel in a HMO

A four floor HMO occupied by one or two families with no floor greater than 200m² would be designated a grade B dwelling. The appropriate level of  fire alarm system in such a building would be LD2. This is obviously not a strict rule and the primary point for assessing the appropriate level of protection required would be the risk assessment specific to an individual building. For use of this article we shall assume that our building requires an LD2 system.

An LD2 system means hallways/stairwells used as escape routes from dwelling areas and areas at high risk from fire (living rooms, kitchens) will require detectors. In our building we could separate it into 3 zones – the two separate accomodation areas and the stairwell that covers 4 floors and each floor having an area of 120m² giving a total of 480m². A 4 zone twinflex system would then be suitable.

An LD2 system needs detectors in stairwells and hallways that are escape routes and more detectors between sleeping areas and other high risk areas. Obviously the sound level needs to be sufficient for each detector and the twinflex multipoint detectors provide 3 output patterns and 2 levels with 90dB. Detection speed  and type of fire need to be taken into account when selecting detectors for rooms like the kitchen or living room to avoid false alarms. A Multipoint detector can provide 7 modes of detection which include a combination detection and the following:

Heat: Rate of Rise, Standard Fixed Temperature – 58°C approx, High Fixed Temperature – 90°C approx

Smoke: Ionisation detection, Optical detection, Reduced Sensitivity

Detectors can be fitted on ceilings at least 300mm horizontally from any wall or light fitting and no point should be further than 7.5m from the nearest smoke detector, 5.3m from a heat detector. No bedroom door should be further than 3m from a smoke detector.

With added call points that can be activated before a fire is automatically detected a Twinflex 4 zone system would be ideal for for our hypothetical building.