161.012-9—Performance.
        
        (a) 
         If a light is a flashing light, its flash rate when first activated, or within five minutes thereafter, must be between 50 and 70 flashes per minute.
    
    
    
        
        (2) 
         Within 5 minutes after activation be capable of being seen from a distance of at least one nautical mile on a dark clear night.
    
    
        
        (c) 
         Each light must be designed to operate underwater continuously for at least 8 hours at a water temperature of 15° ±5 °C (59° ±9 °F). However, if the light needs air to operate, underwater operation is required only for 50 or more seconds during each minute of the eight hour period.
    
    
    
        
        (e) 
         A light that concentrates its light beam by means of a lens or curved reflector must not be a flashing light.
    
    
        
        (f) 
         Each light must be designed to operate in accordance with this section after storage for 24 hours at a temperature of 65° ±2 °C (149° ±44 °F), and after storage for 24 hours at −30° ±2 °C (−22° ±4 °F).