This part of DD 8489 describes tests and specifies requirements for industrial and commercial watermist systems for the protection of low hazard occupancies.

This part of DD 8489 covers low hazard occupancy rooms or spaces within buildings such as churches, clubs, educational facilities, hospitals, institutional facilities, museums, offices, data processing areas without open storage of information media, restaurant seating areas. It also covers corridors able to be protected with a single row of nozzles.

This part of DD 8489 also covers apartments, nursing or convalescent homes and residential facilities with room sizes in excess of those covered by DD 8458‑1.

This part of DD 8489 does not cover rooms or spaces within buildings containing flammable or combustible liquids in any amount. It also does not cover rooms or spaces containing storage exceeding the fuel loads specified in 4.7 to 4.10. Examples include but are not limited to libraries, maintenance areas, workshop areas, machinery areas, laboratories, kitchen areas in restaurants, theatres and auditoria.

This part of DD 8489 is applicable to ceiling heights up to 5 m.