Definition(s)
Preaction System
A sprinkler system employing automatic sprinklers attached to a piping system containing air that may or may not be under pressure, with a supplemental detection system installed in the same area as the sprinklers. Actuation of the detection system opens a valve that permits water to flow into the sprinkler piping system and to be discharged from any sprinklers that may be open.
Source: Resolution A.800(19), Revised Guidelines for Approval of Sprinkler Systems Equivalent to that Referred to in SOLAS Regulation 11-2/12, 23 November 1995, International Maritime Organization. Regulatory Guidance