High Ceiling Clearance – Sprinkler Solutions. 7/11/13
In last week’s blog article, we looked at the challenges of incorporating fire sprinkler protection into fire safe building designs with high ceiling clearance space. In part two, we take a look at the published guidance and building codes relating to buildings with high ceiling clearance and put forward some suggestions as to solutions that could be employed.
Guidance applicable to high ceiling clearance
Fire guidance and national building codes within Europe, which relate to high ceiling clearance spaces requiring sprinkler protection, are very limited.
The installation of sprinkler systems normally follows the ‘Loss Prevention Council (LPC) Rules for Automatic Sprinkler Installations’ which is also referred to as BS EN 12845:2004+A2:2009. This publication, however, does not cover the recommendation and methods to be adopted in respects of sprinkler design within high ceiling clearance facilities.
The only guidance which contains a comprehensive description of fire safety techniques applicable where sprinkler protection is required within a building which includes high ceiling clearance facilities is BS9999.
BS9999 recommends that the uses of the atrium base should be limited by controlling the fire loads. In some atrium designs, combustible contents within the atrium base are not permitted. This will depend on the provision of the smoke control system to protect the atrium space, which does not have sprinklers.
In order to control fire loads at the base of atrium, BS9999 recommends to limit the combustibles loadings to isolated islands (package fire loads) as follows:
• Each island should:
Contain a maximum of 160kg combustible material
Not exceed a maximum floor area of 10m2
Be separated from other areas of combustible materials by at least 4m
• All wall and ceiling linings should have at least a class 1 surface spread of flame when tested in accordance with BS476-7
• All upholstered furniture should resist ignition by the smouldering (ignition source 0) and the flaming (ignition source 5) when tested in accordance with BS5852
• All textiles (drapes and curtains) should meet the requirements of BS5867-2
One of the most common ‘solutions’ to this issue is the restriction of use of the high ceiling clearance area. However, restricted use of such space would significantly impact on the economy beneficial to the building owner.
A way to overcome the problem, without restricting the use of space, could be the use of an effective means of fire suppression protection.
One solution includes giving consideration to the effective detection and control at a closer locality to the fire source. Studies of existing situations, and experiments carried out by research bodies, have shown that one of the most favourable solutions to the problem is to install sprinklers around the perimeter of the high clearance ceiling facilities with an extended horizontal throw, actuated by beam detection covering the affected area.
The beam detection can be installed at a lower level – closer to the fire source -providing a shorter detection time. Eventually, the condition of the affected areas in terms of fire spread will be greatly improved as the sprinkler systems will act in the insipient state of the fire, due to fast detection.
It is recommended that the beam detector be linked to the convention sprinkler nozzles by a multiple jet control (to operate small groups of sprinkler simultaneously). In the event of a fire, the beam detectors will activate and then send a signal to actuate the sprinklers via a control panel. This can be achieved by means of sending an electric signal to the multiple jet controls. An electrically triggered piston actuator is provided, which, upon receipt of an electric signal, shatters the frangible glass bulb to operate the control.
The proposal above is considered to be suitable for the application of an atrium space; however, it may not be suitable for some others applications, i.e. large public concourse areas, where the long throw nozzles cannot be installed to provide a sufficient length of throw to protect the affected areas.
As each design and building requirements are individual, so are the fire engineering solutions which can be put in place to solve potential issues. The best solution currently available to designers and architects is not set down, as it depends on the specific characteristics of the particular building.
Meanwhile, more guidelines must be published in order to provide an effective fire protection to high level ceilings within buildings and thus enable building users to make full use of such areas.
If you would like to discuss this article any further or would like fire engineering guidance for your project, please contact Peter Gyere at Lawrence Webster Forrest on 020 8668 8663.
LWF are fire engineering and fire risk management consultants with more than twenty years experience in the development of fire engineered technology and the application of fire safety standards including fire engineered techniques.