Working with the cooling system, not against it, gaseous fire extinguishing can have enhanced performance, better safety (life and asset / business continuity) and actually work out cheaper by optimising room and floor pipe diameters saving on labour and material costs.
I see some clients that have installed fire extinguishing system nozzles within the cold aisle itself; worst still, some have paid for a retrofit when the aisle was added. This worries me. With good-intent many a mistake can be made, or so I think …
Whilst I understand the designer probably saw this as the best means to get extinguishing agent to the critical asset asap, the acoustic implications of placing a nozzle in close-proximity to Hard Disk Drives (HDDs) – and then containing this, so the negative connotations of the “room radius” is exaggerated by the physical aisle enclosure itself – is cause for concern.
I know there is mixed opinions in the industry, but working with some brilliant people I still believe the solution is to overflood the subfloor, when this is used as a supply plenum, and include in this the volume of the cold aisle and critical asset. The volume deduction of aisle and racking made from the room volume. No more extinguishant is used, but what you have is used most effectively.
This approach works in harmony with the quiescent cooling philosophy, and where pressure venting is placed downstream it ensures the quickest possible flame knockdown, although one always aspires for a system to be designed to avoid flaming combustion altogether.
Whilst I hung this particular subject-matter hat up a while ago – this was big news in the industry a decade back – we still witness casualties and I still enjoy assisting the few at risk or needing help.
This does not remove the need for ‘silent’ type nozzles, but can reduce the number of nozzles and actually, through balancing agent flow in pipe diameters, can optimise the cost of labour and materials for a cheaper solution too.
Know-how and experience are invaluable, but sadly such is usually gained at someone’s (costly if not devastating) expense.