Section 325.60606. Immediate evacuation warning signal.

Rule 6.  (1) The following apply to signal characteristics:

(a)        The signal shall be a midfrequency complex sound wave amplitude modulated at a subsonic frequency. The complex  sound  wave  in  free  space shall have a fundamental frequency (f1) between 450 and 500 hertz  (Hz) modulated at a subsonic rate between 4 and 5 hertz.

(b)      The signal generator shall not be less than 75 decibels at every location where an individual may be  present  whose   immediate,  rapid,  and  complete evacuation is essential.

(c)    A sufficient number of signal units shall be installed so the requirements of subrule (1)(b) of this rule are met at every location where an individual may be present whose immediate, rapid, and complete  evacuation is essential.

(d)    The signal shall be unique in the plant or facility in  which  it  is installed.

(e)        The minimum duration of the signal shall be sufficient to ensure that all affected persons hear the signal.

(f)     The signal-generating system shall respond automatically to an initiating event without requiring any human action to sound the signal.

(2)     The following apply to design objectives:

(a)       The signal-generating system shall be designed to incorporate components which enable the system to produce the desired signal each time it is activated within one-half second of activation.

(b)     The signal-generating system shall be provided with an automatically activated secondary power supply which is adequate to simultaneously power all emergency equipment to which it is connected, if operation during power failure is necessary, except in those systems using batteries as the primary source of power.

(c)      All components of the signal-generating system shall be located to provide maximum practicable protection against damage in case of fire, explosion, corrosive atmosphere, or other environmental extremes consistent with adequate system performance.

(d)     The signal-generating system shall be  designed  with  the  minimum number of components necessary to make it function as intended, and should utilize components which  do   not  require  frequent  servicing   such  as lubrication or cleaning.

(e)       Where several activating devices feed activating information to a central signal generator, failure of any activating device shall not render the signal-generator system inoperable to  activating information  from  the remaining devices.

(f)     The signal-generating system shall be designed  to   enhance  the probability that alarm occurs only when immediate evacuation is warranted. The number of false alarms shall not be so great that the signal will come to be disregarded and shall be low enough to minimize personal injuries or excessive property damage that might result from such evacuation.

(3)     The following apply to testing:

(a)     Initial tests, inspections, and checks of the signal-generating system shall be made to verify that the fabrication and installation   were made according to design plans and specifications and to develop a thorough knowledge of the performance of the system and all  components  under  normal and hostile conditions.

(b)        Once the system has been placed  in  service,  periodic  tests, inspections, and  checks  shall  be  made to  minimize  the  possibility of malfunction.

(c)      Following significant alterations or revisions to the system, tests and checks similar to the initial installation tests shall be made.

(d)    Tests shall be designed to  minimize hazards while conducting the tests.

(e)      Before normal operation, the signal-generating system shall be checked physically and functionally to assure reliability and to demonstrate accuracy and performance.  Specific tests shall include all of the following:

(i)     All power sources.

(ii)     Calibration and calibration stability.

(iii)     Trip levels and stability.

(iv)     Continuity of function with loss and return of  required  services such as AC or DC power and air pressure.

(v)     All indicators.

(vi)     Trouble indicator circuits and signals, where used.

(vii)     Air pressure, if used.

(viii)     Determine that sound level of the signal is within the limit  of subrule (1)(b) of this rule at all points that require immediate evacuation.

(f)       In addition to the initial startup and operating tests, periodic scheduled performance tests and status checks shall be made to ensure that the system is at all times operating within design limits and capable of the required response. Specific periodic tests or checks or both  shall  include all of the following:

(i)     Adequacy of signal activation device.

(ii)     All power sources.

(iii)      Function of all alarm circuits and trouble indicator circuits including trip levels.

(iv)     Air pressure (if used).

(v)     Function of entire system including operation  without  power  where required.

(vi)          Complete operational tests including sounding of the signal and determination that sound levels are adequate.

(g)      Periodic tests shall be scheduled on the basis of need, experience, difficulty, and disruption of operations. The entire system shall be operationally tested at least quarterly.

(h)     All employees whose work may necessitate their presence in an area covered by the signal shall be made familiar with the actual sound of the signal--preferably as it sounds at their work location. Before placing the system into operation, all employees normally working in the area shall be made acquainted with the signal by actual demonstration  at  their  work locations.

History: 2009 AACS.