Q.For how long the fire alarm must ring?

if detector is acitivated , the audible alarm should be immediated at the control panel and indicated unit. and then if the alamr is not acknowledged  in 2 minutes, the audible alarm will be acitivated throught all crew accommodation and control station/ service space and other public space etc.

Until everyone(if possible) musters at the designated muster station of the ship. Then master or OOW acknowledge the fire alarm upon confirmation from the chief officer.

until the fire was estinguish.!!!