LK-CT International standards for industrial warning devices have established minimum differential sound output levels that must be complied with.The dB level of the siren must be at least 15 dB higher than that of the measured ambient noise.The siren must,however,have a minimum sound output of 65 dB.The sound frequency of the siren,at the point where the sound output is greatest,must differ as much as possible to the frequency of the ambient noise.

SELF-EXTINGUISHING

Two factors determine the capacity of the sound to be heard: 

1.the distance between the audible warning device and the operator;

2.the existing ambientnoise

The suitability of an sudible alarm for a specific appplication is determined by its specification:

1.sound output DECIBEL(dB)

2.sound frequency HERTZ(Hz)