Code of Federal Regulations Title 46. Shipping § 46.108.445 Alarm and means of escape

(a) Each CO₂ system that has a supply of more than 136 kilograms (300 pounds) of CO₂, except a system that protects a tank, must have an alarm that sounds for at least 20 seconds before the CO₂ is released into the space.

(b) Each audible alarm for a CO₂ system must have the CO₂ supply for the system as its source of power and must be in a visible location in the spaces protected.