Sir, – Further to "Children's hospital board appeals requirement for sprinkler system" (October 22nd), sprinklers systems fall into two main categories – wet and dry.Wet systems have the pipework filled with water; dry systems are filled with pressurised air or nitrogen, and are used where there is a risk of freezing.
Sprinkler heads may be closed or open. Open heads are used in dry-pipe deluge systems where a fire can spread rapidly, such as warehouses or similar large open structures.
Sprinklers in non-industrial buildings such as offices, schools and hospitals are typically wet systems with closed heads.
Each sprinkler head has a component that melts or breaks in the event of a fire in its vicinity, thus allowing water to be sprayed only from those heads that have been subjected to heat from the fire. If all sprinklers in a building were to discharge simultaneously then huge water storage tanks and pumps would be required, and rooms not on fire would suffer water damage.
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A letter-writer (October 27th) appears to argue that it is justifiable to delete the proposed sprinkler system for the new national children's hospital. She writes that patients in wards and operating theatres would be drenched if someone had a sneaky cigarette.Sprinkler systems do not work that way, and I am surprised that she appears to believe that they do.
The level of security and safety that sprinkler systems provide has been well proven over the last 80 years. Deleting the sprinklers would be daft. – Yours, etc,
JOHN LARKIN,
Sandymount,
Dublin 4.