Calculation of the coverage area of ​​premises by the SONATA voice alarm system.

Calculation of the coverage area of ​​premises by the SONATA voice alarm.

Calculation of the coverage area of ​​premises by the SONATA voice alarm.

According to paragraph 4 of the Code of Rules No. 3.13130.2009, sound signals must provide a general sound level of at least 75 dBA at a distance of 3 m from the alarm device, but no more than 120 dBA at any point in the protected room. Sound signals of the fire alarm system must provide a general sound level of at least 15 dBA higher than the permissible sound level of constant noise in the protected room. Sound levels must be measured at a distance of 1.5 m from the floor. Wall-mounted sound and speech alarms must be located so that their upper part is at least 2.3 m from the floor level, but the distance from the ceiling to the upper part of the alarm device must be at least 150 mm.

To calculate the coverage area for the Sonata-3 or Sonata-3 ver.2 voice alarm, use the following formula:

 
S = (6.9) (10Y),
where:      Y = 3.98 – 0.05 ( Lш – К )

Here:
             Lш – permissible noise level of a given room, dB  
                   K – coefficient taking into account the wall material.

In this case:
K=3, if the wall material is plaster, gypsum fiber, chipboard or other, the diffuse absorption coefficients of which are less than 0.25.
K=0, if the wall material is fabric or soft flooring.
If the distance to the opposite wall is more than 8 m, then also K = 0.
      
Let's calculate the area for the Sonata-3 and Sonata-3 ver.2 voice alarm:

Table 1. Calculation of coverage area for Sonata-3, Sonata-3 version 2

 
The table presents the results of calculating the sound distribution area in m? depending on the permissible noise level in the room and the material of the reflective surfaces. The following assumptions were made:

1. the room is devoid of furnishings.
2. the calculation was made according to statistical theory for average climatic conditions.
3. Ceiling height 4…5 m, loudspeaker suspension level 2.3…3.5 m (according to clause 3.17 NPB104-03).
4. The obtained figures are valid only for Sonata-3, Sonata 3 ver.2 sounders.

 
             Similarly, we will calculate the coverage area for Sonata-5, Sonata 5 ver.2 sounders.
Considering that the Sonata-5 and Sonata 5 ver.2 voice alarms have a sound power of 5 W and a sound pressure level at a distance of 3 m: 86±7% dB, the formula for calculating the area is transformed as follows:

S = (6.9) (10Y),
where:      Y = 4.09 – 0.05 ( Lш – К )

Then the calculation result is presented in Table 2.

 
Table 2. Calculation of the coverage area for Sonata-5, Sonata 5 ver.2  

Marketing analyst, Paul N.P. (PollNP@arsec.ru)