Hospital APS and EPSS Project

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 sleeping 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 sleeping person's 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. "

For hospital premises, SP 3.13130.2009 indicates (Table 2, item 3):

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

Thus, audible annunciators should be located only in the premises where the staff of the institution are located.

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 :

- "Room" (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.).

A room contains one alert.

In the other two types of rooms - several, evenly located, alerts will be placed.

Note that most of the spaces of the object in question are "room" spaces with an area not exceeding 20 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 regulates the noise level for the offices of doctors of hospitals, clinics, sanatoriums 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 residence room is 5.6 x 3.7 meters in size.

For such premises Ush is normalized with the value of 35 dBA, (SNiP 23-03-2003

item 6, Table 1).

At that Utr will be 35 + 15 = 50 dBA

According to Assumption 2, this room is a room type, 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 5.95 m .

Sound attenuation at this distance is 16 dBA.

The required sound level of the alert is:

Utr. Op. = 50 + 16 = 66 dBA.

Thus, to comply with SP 3.13130.2009 norms, it is enough to use Sonata-T-100-3/1 type alerts, in which Uzv.d is 90 dBA.

Example 2. The wardrobe room is 7.5 meters long and 5.7 meters wide.

Accept Ush equal to 45 dBA.

At that Utr will be 45 + 15 = 60 dBA

Under Assumption 2, this room is also a room.

The height of the wall alert is 2.3m.

With such dimensions of the room and arrangement of annunciators, the distance to the design point will be 8.1 m.

Attenuation at this distance is about 18 dBA.

The required sound level of the alert is:

Utr. Op. = 60 + 18 = 78 dBA.

Thus, to fulfill the requirements of SP 3.13130.2009, it is enough to use one Sonata-T-100-3/1 type alert.

Having calculated according to the above procedure, we obtain:

• Sonata-T-100-3/1 annunciator 0 shall be used for sounding of rooms in the 4 area. The total power of the annunciators will be 18 W, i.e. one 50 W amplifier is enough to power the annunciators;

• Sonata-T-100-3/1 annunciator 1 shall be used for sounding of rooms in the 22 area. The total power of the annunciators will be 66 W and for their power it is necessary to use 2 amplifiers of 50 W;

• 26 Sonata-T-100-3/1 annunciators shall be used for sounding of premises of zone 2. The total power of the annunciators will be 78 W and for their power it is necessary to use 2 amplifiers of 50 W;

• 7 Sonata-T-100-3/1 annunciators shall be used for sounding of 3 zone premises. The total power of the annunciators will be 21 W and one 50 W amplifier is enough to power them;

• 7 Sonata-T-100-3/1 annunciators shall be used for sounding of premises of zone 4. The total power of the annunciators will be 21 W and one 50 W amplifier is enough to power them.

Thus, to power the annunciators of the 1st and 2nd zones in addition to the BAS-4 device (power 50 W), it is necessary to use one BUM1/4 amplifier per zone.