Current affairs
• extensive cable trays creating obstructions to nozzle discharge
• use of drop away heat sensitive panels • high heat outputs from the computer equipment required that generate high air flows/velocities
• hot and cold aisle enclosures within rooms • cooling that must remain on, even under fire conditions
• plenums • air movements via a floor void and through server cabinets pushing the heat and mist directly away from the computer equipment
•
assimilated air movement with high/low level fans and egg crate and ventilated ceilings
When I reviewed a design scheme for the use of watermist for a large data centre in North America, the following important concerns were immediately identified at proposal stage: • the fire test data approval for the watermist system was based upon testing with no ventilation – data centres will not shut down cooling, even under fire conditions
• the fire test protocol stated that wet pipe systems only are to be used – the system on site was designed as pre action
• •
there was no protection for the plenum void, despite the building having a 12ft plenum
there was no protection for the enclosed hot aisles
• the test protocol provided failed to take into account the considerable quantity of obstructions such as cable trays and race ways directly above the server cabinets
•
fire penetration into plenums would circulate products of combustion around the data hall – there was no means of extracting air flow upon fire conditions
• ceiling heights were greater than those detailed within test protocol provided
The good news is that in recent years there has been independent fire testing undertaken by a number of manufacturers for the protection of data centres. It is important to read carefully and cross map the fire test data provided by the watermist manufacturer to the specific geometry, layout and nature of the data centre to ascertain that the proposed watermist system is fit for the purpose of protecting it from the risks specific to it.
Waste and recycling Provision of active fire protection systems in these types of plants provides serious challenges to the planner, designer and user, not least of which is the unpredictability of the waste intake coupled with the sheer volumes or throughputs of materials. Such fires have the potential to burn for days
or even weeks, can have a huge impact on the local community, the environment, and the economy, and can involve the commitment of
FOCUS
www.frmjournal.com DECEMBER 2019/JANUARY 2020
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