APS in the building of the AZPM engineering complex

Electroacoustic calculation

The main requirements for the fire evacuation warning and control system (EPSS) are set forth in SP 3.13130.2009 "Fire protection systems. Warning and management system for evacuation of people in case of fire. Fire safety requirements ":

"4.1 EMSS sound signals shall provide a common sound level (constant noise sound level together with all signals produced by the annunciators) of at least 75 dBA at a distance of 3 m from the annunciator, but not more than 120 dBA at any point in the protected room.

4.2 EMSS sound signals shall provide sound level not less than 15 dBA higher than permissible sound level of constant noise in the protected room. The sound level shall be measured at a distance of 1.5 m from the floor level.

4.3 In working rooms, EMSS sound signals shall have a sound level not less than 15 dBA above the sound level of constant noise in the protected room, but not less than 70 dBA. Measurements should be taken at the level of the human head.

4.4 Wall sound and voice annunciators shall be so positioned 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 annunciator shall be at least 150 mm. "

In relation to the office building, SP 3.13130.2009 indicates :

"When applying the 3rd type of EPSS and above, people are notified using a special warning text. Such text should not contain words that could cause panic. "

Thus, audible alerts should be placed in the corridors of the building.

The electroacoustic calculation for a particular room answers the questions: "How many speakers, what capacity and where it is necessary to arrange in this room in order to fulfill the requirements that are imposed on the warning system." Knowing the results of the calculations for each room, you can calculate the required power of the amplifiers of the sound warning system for the entire building.

Acoustic calculation in general is quite complex, therefore, in practice, to simplify calculations, the following assumptions are used:

Assumption 1. Based on the geometric dimensions of spaces, all spaces are divided into only three types :

- "Cabinet" (area up to 40 sq.m., length not exceeding 1.75 width),

- "Corridor" (length exceeds width by 2 times or more),

- "Hall" (area more than 40 sq.m.).

In the room of the type "Office" alerts will not be located.

In the room of the "Hall" type there is a red light strobe.

Corridor space - Several evenly spaced alerts will be placed.

Note that most of the premises of the object in question are rooms of the type "Cabinet" with an area not exceeding 40 sq.m.

Assumption 2. The loudspeaker emits a "spherical" wave, i.e. the sound pressure in any direction from the loudspeaker will be the same. At the point of greatest removal (R) from the source of oscillations is the "design point" - the point at which it will be necessary to know the level of sound pressure produced by this source of oscillations .

The initial data for the calculation are:

- loudspeaker characteristics, namely sound pressure level (at rated supply voltage) measured at a distance of 1 m from the loudspeaker;

- geometric dimensions of the voiced room;

- noise level (dBA) in the room;

- method of loudspeakers installation.

The sound pressure level (Usv, dBA) is given in the documentation of the loudspeaker manufacturer.

The noise level (Ush, dBA) in the room is normalized depending on the purpose of the room and is given in the reference literature, for example in SNiP 23032003 .

In our case, SNiP 23032003 normalizes the noise level for cabinets of 35 dBA.

The required sound level at the design point Utr is defined as Ush + 15, dBA.

The attenuation of the sound signal depending on the distance has a quadratic dependence and can be easily determined using an appropriate table or calculation method.

Example 1. The Corridor room on the 1st floor is approximately 150m2.

For such premises Ush is rated 7075 dBA, (SNiP 23032003)

At that Utr will be 75 + 15 = 90 dBA

According to Assumption 2, this room is a Corridor type room for which the installation of the 1st loudspeaker is applied. The height of the wall speaker is 2.3m.

With such room dimensions, the distance to the calculation point will be 9.95 m .

Sound attenuation at this distance is 6 dBA.

The required sound level of the alert is:

Utr. Op. = 90 + 6 = 96 dBA.

Thus, in order to comply with the norms of SP 3.13130.2009, it is enough to use alerts of type EGA265A, in which Uzv.d is 98 dBA.

Having calculated according to the above procedure, we obtain:

8 EGA265A alerts shall be used for sounding of corridor rooms on 4 floors. The total power of the annunciators will be 48 W, i.e. no amplifiers are required to power the annunciators;

Thus, the output power of the voice warning device "HORN" is enough to power the corridor alerts.