Definition
Pre-action (especially double-interlock) is the default for areas where accidental water discharge would be catastrophic: data centres, museums, archives, MRI suites. Detection comes from VESDA aspirating or spot smoke heads. EN 12845 §11.2 and NFPA 13 §8.3 describe the three pre-action variants (non-interlock, single-interlock, double-interlock).
Referenced in
- EN 12845
- NFPA 13