Purpose and device of light and sound annunciators. Technical security systems Installation of light and sound annunciators

CM. Shchipitsyn
CEO of "System Sensor Fair Detector" LLC

In case of fire, the warning system is the link between the automatic fire alarm system and people. At first glance, bells, strobes and sirens seem to be the simplest components of a public address system, but in public and administrative buildings they are the only source of signals that call people for immediate evacuation.

The article presents the requirements of Russian and foreign regulatory documents for such systems, practical recommendations for the placement of annunciators, as well as the latest technologies for determining the exit path using the guiding audio signal.

Russian regulations

The general procedure for designing fire warning systems is defined in NPB 104-03 "Warning and evacuation control systems for people in case of fires in buildings and structures." The norms provide for 5 types of warning and evacuation control systems (SOUE), depending on the method of notification, dividing the building into warning zones and other characteristics. The sound or light-sound warning method in the form of sirens and strobe lights is used in the simplest warning systems of the 1st and 2nd type.

The characteristics of the annunciators must comply with the requirements of NPB 77-98 "Technical means of alerting and managing the evacuation of firefighters. General technical requirements. Test methods" According to the classification given in the document, annunciators are divided into light, sound, speech and combined. distance of 1 ± 0.05 m, should be set between 85-110 dB.

According to NPB 104-03, sound signals of SOUE should provide the sound level:

not less than 75 dB at a distance of 3 m from the annunciator, but not more than 120 dB at any point of the protected premises,
to ensure clear audibility - at least 15 dB above the permissible sound level of constant noise in the protected room (measurements are taken at a distance of 1.5 m from the floor level),
in sleeping rooms - not less than 15 dB above the sound level of constant noise in the protected room, but not less than 70 dB (measurements are taken at the level of the head of a sleeping person).

Wall-mounted sounders (Fig. 1), as a rule, should be mounted at a height of at least 2.3 m from the floor and at least 15 cm from the ceiling. In rooms where people are wearing noise-protective equipment or with a noise level of more than 95 dB, sound annunciators must be combined with light ones, the use of flashing light annunciators is allowed. In buildings where there are deaf and hard of hearing people, light or light flashing annunciators are also used.

The degree of protection of technical means of warning, provided by the shell in accordance with GOST 14254, must be at least IP 41.

Foreign requirements for warning systems

The requirements of domestic standards for many components of fire alarm systems practically coincide with the national standards of other countries, but significant discrepancies remain for warning systems.

In European systems, a minimum alert signal level of 65 dB is allowed with a decrease to 60 dB in rooms with an area of less than 60 m2, on landings and at certain points of limited space (Fig. 2, a), in rooms with operating equipment, it is sufficient to exceed the noise level by 5 dB (Fig. 2, b), and not by 15 dB, as in Russian standards. In sleeping quarters (Fig. 2, c), the signal level at the head level of a sleeping person should be 75 dB, in contrast to the Russian 70 dB.

According to NFPA72 (US National Fire Code, Revision 1993), sounders are installed in almost the same limits - at least 90" from the floor and not less than 6" from the ceiling (1" = 25.4 mm) When installing combined stroboscopic light and sound devices, this requirement is replaced by the corresponding requirement for the installation of strobe devices.

In rooms with working mechanical equipment, an alarm signal level of at least 85 dB must be ensured, as opposed to 75 dB for other rooms. In NFPA72, in addition to the "general" mode of operation of the voice alarm system, the so-called address mode is regulated. It is used for the posts of nurses on duty, security services, etc. The requirements for it are much lower: the alert signal level is at least 10 dB above the average background noise level and at least 5 dB above the maximum noise level for at least 60 s duration, but not less than 45 dB. These requirements can be guided by when calculating the alert system for service personnel based on warning signals about a fire hazardous situation, generated, for example, by analog addressable and laser aspiration SPS. Most modern sound annunciators from the world's leading manufacturers have the ability to adjust the sound level.

Sound warning systems

Type of sound signals of fire alarms
According to NPB 104-03, audible warning signals must differ in tone from audible signals for other purposes. In NFPA72, in order to eliminate the possibility of misinterpretation of an alarm signal, the type of audible signal used in fire alarm systems is standardized. The type of signal is periodic, each period is 4 s and consists of 3 pulses with pauses: sound signal 0.5 s, pause 0.5 s, sound signal 0.5 s, pause 0.5 s, sound signal 0.5 s, pause 1.5 s (Fig. 3). According to NFPA72, the total minimum signal duration is 180 s, according to NPB 104-03, the SOUE must function for the time necessary to complete the evacuation of people from the building.

Location of sounders
The number of sound fire alarms, their placement and power must ensure the sound level in all places of permanent or temporary stay of people in accordance with the requirements of NPB 104-03. The initial data for the calculation in the simplest case are the dimensions of the room and the minimum required level of sound signals, which is determined by the type of room (sleeping or working), the permissible noise level in it, etc. The table shows typical noise levels from the most common sources.

For example, for a bedroom with an exhaust fan, the required alarm level should be at least (55 + 15) = 70 dB. To do this, the siren signal must exceed the specified value by the amount of attenuation when it propagates to the most remote part of the room. The signal level at an arbitrary distance is determined by adding the passport value of the siren signal (by 1 m) with the signal attenuation value (with a "minus" sign) for a given distance . The value of the signal attenuation in dB at a distance L in meters, relative to its value at a distance of 1 m from the annunciator, can be calculated by the formula:

Thus, if the siren at a distance of 1 m provides a signal level of 100 dB, then at 10 m the attenuation is -20 dB and the signal level will be 80 dB.

When using several annunciators in one room, it must be taken into account that the value of two equal signals during in-phase addition increases by 2 times, that is, by only 3 dB. When using one siren for several rooms, it is necessary to take into account the attenuation of the signal when passing through the doors. According to the European calculation method, in the general case, the signal attenuation is -30 dB - for fire doors, -20 dB - for standard doors (Fig. 4).

Light warning systems

There are no detailed recommendations on the use of light and combined light and sound annunciators in the domestic regulatory framework. To solve practical problems, you can refer to the American regulatory requirements.

When choosing equipment and determining the installation locations of light annunciators, it is necessary to distinguish between the type of premises: a sleeping room; a room other than a bedroom, or a corridor.

Location of light alarms in the premises
NFPA72 establishes extremely clear requirements for the total number of gates and the distance between them, depending on the type of room, its size, the luminous intensity of the siren and its installation location. In diagram 1, for rooms other than bedrooms, the minimum luminous intensity values for 1, 2 and 4 wall-mounted sirens are shown.

When using two sirens, they must be installed on opposite walls; if more than two sirens are used, their light pulses must be synchronized. Synchronization of sirens in analog addressable systems is performed automatically, in traditional systems it is necessary to use an additional wire. In rooms 80x80 feet (approximately 24.4x24.4 m) and larger, where there may be more than two sounders, the distance between installed devices must be at least 55 feet (approximately 16.8 m).

In areas other than bedrooms, wall mounted beacons should be mounted on walls 80 to 96 inches (approximately 2 to 2.5 m) from the floor and a minimum of 6 inches (approximately 15 cm) from the ceiling.

The requirements for ceiling light annunciators (Fig. 5) in terms of luminous intensity (in candela) depending on the size of the room are shown in diagram 2. These data can only be used when installing the strobe in the center of the room, otherwise the level of luminous intensity should be determined based on the room , the dimensions of which are equal to twice the distance from the siren to the farthest wall. When ceiling heights exceed 30 feet (approximately 9 m), NFPA72 mandates that beacons be installed either on walls or on special attachments so that the distance from the floor to the sounders does not exceed 30 feet.

The distances between the individual devices in the system and the exact mounting locations of the strobe lights depend on the size and configuration of the protected area or area. The stipulated requirements are based on the basic calculation for a square room. Gates are placed asymmetrically, but in such a way that each of them provided an alert in one of the quarters of the room (Fig. b, a). For this example, the operation of the gates must be synchronized. If the gates are placed in the centers of the walls, the level of signals in the corners of the room will be unacceptably low (Fig. b, b). In rooms of arbitrary configuration, with the exception of corridors, for the calculation according to Scheme 2, one or more squares of such a size are used that the room of a given shape fits completely.

For bedrooms, a wall strobe mounted 24 inches (610 mm) or more from the ceiling should provide 110 candela and 177 candela if less than 24 inches (610 mm) away. Accordingly, the ceiling light annunciator must also provide a luminous intensity of 177 candela. In any case, the strobe should be installed no more than 16 feet (approximately 5 m) from the level of the pillow in plan (Fig. 7).

Location of light annunciators in the corridors
For corridors, 15 candela strobes must be mounted no more than 15 feet (approximately 4.5 m) from the ends of the corridor. The maximum distance between two adjacent gates must not exceed 100 feet (approximately 30.5 m). Moreover, any parts of the corridor in which there is a violation of the continuity of the view should be interpreted as separate corridors. A typical arrangement of light annunciators in corridors of various types is shown in fig. eight.

Acoustic emergency exit indicators

All audible signals used during evacuation are alarms, they do not give information about the direction to the nearest fire exit, nor about its location. Such a goal is not set when using them, it is only necessary to sound at the required level all the premises where people can be.

The bulk of emergency exit signs (emergency lighting, markings, wall and door color codes, photoluminescent guide strips, etc.) involve only visual perception. But such signs become ineffective if part of the building is completely or partially filled with smoke or a person has vision problems.

The natural solution is to use special types of sound. For example, a broadband pulsed noise signal with a continuous spectrum over the entire audio range is quasi-white noise. The source of such a sound is easily and quickly determined by the human ear, making this method ideal for ensuring rapid evacuation. Activated by an existing fire alarm system, a directional sound source placed at carefully selected locations emits audible signals to help people find their way to emergency exits. The guiding sound technology is used by sound annunciators of the new ExitPoint class (Fig. 9).

The evacuation stage is transmitted by the frequency of pulses (ripples) of the noise signal. The "fast" speed pulsation mode is used to designate an evacuation exit, the "medium" speed mode - to create a direction of movement for the evacuation exit, the "slow" pulsation mode designates an exit from the interior of the building (Fig. 10). In the pauses between the emission of a noise guide sound, speech information messages or additional sound signals can be played.

Messages (for example, "Exit", "Stairs up", "Stairs down", "Shelter area") or additional signals: an increasing frequency siren (up stairs), a siren decreasing in frequency (down the stairs), a standard fire alarm sound signal - three single-frequency pulses with a pause (see Fig. 3). The type of additional sound signals allows a person to intuitively determine their meaning even in a stressful environment.

ExitPoint sound indicators do not replace traditional sound and light annunciators, but are used as auxiliary devices in the fire alarm notification system and speed up the evacuation process of people in the building. The sound signals of fire alarms have narrow spectra and practically do not interfere with the localization of ExitPoint broadband signals. When combined with a voice announcement, it is possible to separate the announcement by time, indicating in the text the technology for using ExitPoint guiding sound signals.

In conclusion, it should be noted that a competent approach to the process of designing a warning system in accordance with Russian airbags will allow the use of foreign regulatory frameworks as recommendations. The use of such latest technologies as guiding sound in warning and evacuation control systems will be able to ensure the proper level of safety for people in the building.

Connecting an audible annunciator and a light annunciator to the Eritea Micra 2M and Eritea Mikra 3 alarms

Sound annunciator(howler for current up to 0.2 A and voltage 12 Volts) and light annunciator(LED lamp for current up to 0.2 A and voltage 12 Volts) are connected directly to the alarm device. Consider the connection using the example of a light and sound (combined) annunciator MAYAK-12-KP. The sound and light alarm control channels operate independently of each other.

With factory settings sounder when the alarm is processed by ZONES 1…4, it turns on for 1 minute, when the system is armed or disarmed, a short sound signal is emitted. RELAY 1 is used in the system to control the sounder, RELAY 2 to control the lighter. If the system does not provide for the connection of a sound or light annunciator, then RELAY 1 and RELAY 2 can be reprogrammed to solve other problems.

Change Control Options sound annunciator can be through the configuration program "Erythea Micra 3":

Connecting a street sounder to the Eritea Mikra 2M and Eritea Mikra 3 alarms

Consider the connection diagram of a street siren Ademco 702 to alarms Eritea Mikra 3 and Eritea Micra 2M. The current consumption of the siren is quite large, so we connect this siren through the built-in alarm RELAY 3 to an external backup battery. When RELAY 3 is triggered (we set the relay 3 trigger time to 20 seconds so that the siren does not completely discharge the battery when turned on), the Ademco 702 siren turns on and operates from a backup battery. Connection schemes:

Go to tab 17 (RELAY 3) and set the operation of RELAY 3 in the "HORNER" mode (the parameter is circled in red), set the turn-on time (the parameter is circled in green) and the number of the zone, when triggered in the "ARM" mode, the siren will be turned on ( the parameter is circled in blue, in this example the siren will turn on when an alarm occurs in ZONE 1).

Remote setting of sounder control parameters

If necessary, you can remotely adjust the sounder control parameters by sending an SMS message to the device's SIM card number in the following format:

#RN=2,p1p0,m1m0-s1s0,d,bip,s

N- number of the relay (1-6) that controls the siren (by factory settings -1);
p1p0- pause before turning on the howler (from 00 - 59 seconds, two-digit number, for example, seven seconds: 07);
m1m0-s1s0- Howler's operating time (minutes-seconds, for example, one minute: 01-00);
d- the "DELICATED HORROWER" mode is disabled (parameter = 0), or enabled (parameter = 1);
bip- parameter "Short-term beep when arming and disarming", the mode is disabled (parameter = 0) or the mode is enabled (parameter = 1);
s- "Turn on howler on alarm by" option:

0 - howler work is blocked;
1 - for ZONE 1;
2 - ZONE 2-4;
3 - ZONE 1-4.

Example. It is required to remotely set the following parameters for the operation of the sound annunciator (howler):

the siren is connected to RELAY 1;
pause before switching on - 3 seconds;
siren operation time – 1 minute 12 seconds;
mode "DELICATE HORROWER" is off;
the parameter "Short-term beep on arming and disarming" is enabled;
parameter "Enable horn on alarm on" - ZONE 1-4

The command looks like this:

#R1=2.03.01-12.0.1.3

Write the command without spaces as the text of an SMS message on the phone and send a message to the SIM card number of the device.

The purpose of this article is to acquaint designers, installers and integrators of warning systems, sound systems, public address systems with the basic principles and features of electroacoustic calculation. The main attention in this article is paid to the peculiarities of the arrangement of voice annunciators (loudspeakers) in closed protected premises.

One of the main tasks to be solved in the process of electro-acoustic calculation performed at the initial stage of designing fire warning systems - SOUE is the task of selecting and arranging voice annunciators (hereinafter referred to as loudspeakers). Loudspeakers can be installed both in open areas and in closed (protected) premises. The purpose of this article is to propose and justify options for the optimal placement of voice annunciators (hereinafter referred to as loudspeakers) in closed (protected) premises.

In enclosed spaces, it is recommended to install internal loudspeakers, as the most optimal in terms of parameters and quality. Depending on the configuration of the room, these can be ceiling or wall types. Proper placement of loudspeakers allows you to ensure even distribution of sound in the room, therefore, to achieve good intelligibility. If we talk about sound quality, it will be determined mainly by the quality of the selected speakers. So, for example, when using ceiling loudspeakers, it must be taken into account that the sound wave from the loudspeaker propagates perpendicular to the floor; m from the floor (according to regulatory documentation). In most tasks for calculating ceiling acoustics, sound waves are identified with geometric rays, while the radiation pattern (DN) of the loudspeaker determines the parameters (angles) of a right-angled triangle, therefore, to calculate the radius of a circle (leg of a triangle), the Pythagorean theorem is sufficient. For uniform sounding of the room, the loudspeakers should be installed so that the resulting areas touch or slightly overlap each other. In the simplest case, the required number of loudspeakers is obtained from the ratio of the sounded area to the area sounded by one loudspeaker.

One of the main parameters that needs to be determined in the calculations is the Loudspeaker Chain Spacing. It will be determined by the size of the room, the height of the loudspeakers and their directivity pattern (SPD).

When arranging wall-mounted loudspeakers in corridors along one wall, the recommended spacing is:

excluding reflections from walls:
(Spread spacing, m) = (Corridor width, m) x 2
taking into account reflections from the walls:
(Spread spacing, m) = (Corridor width, m) x 4

When arranging wall-mounted loudspeakers in rectangular rooms on two walls in a checkerboard pattern, the spacing step is:

(Spread step, m) = (Width of the room, m) x 2

When placing wall-mounted loudspeakers in a rectangular room on two walls, the spacing step is:

(Spread spacing, m) = (Half the width of the room, m) x 2

Primary requirements

Here is the main requirement of regulatory documentation (ND):

The number of sound and speech (loudspeakers) fire alarms, their arrangement and power must ensure the sound level in all places of permanent or temporary stay of people in accordance with the norms of this set of rules.

Installation of loudspeakers and other voice annunciators (loudspeakers) in protected premises should exclude concentration and uneven distribution of reflected sound.

Voice annunciators (loudspeakers) should be located in such a way that at any point of the protected object where it is required to alert people about a fire, the intelligibility of the transmitted speech information is ensured.

The design of warning systems is accompanied by the performance of an electro-acoustic calculation (EA). The consequence of a competent EAR is optimization - minimization of technical means, improving the quality of perception. The quality of perception, in turn, is characterized by sound comfort for background music and intelligibility for speech messages. The criterion for the correctness of the EAR is the requirements of regulatory documentation (RD), which can be conditionally divided into:

requirements for a voice annunciator (loudspeaker);
requirements for the levels of sound signals;
requirements for the placement of voice annunciators (loudspeakers).

It should be noted that the RD sets out only the necessary (minimum) requirements, while sufficient (maximum) requirements are provided by the presence of competent methods, and in their absence, by the literacy and responsibility of the designer.

Speaker Requirements

The following requirements are set out. Sounders must provide a sound pressure level such that:

The sound signals of the SOUE provided a total sound level (the sound level of constant noise together with all the 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 of the protected premises.

This paragraph contains two requirements - the requirement for minimum and maximum sound pressure.

Minimum sound pressure

The loudspeaker must provide a (minimum) sound level at a distance of 1 m from the geometric center:

Maximum sound pressure

Let's give the definition of the calculated point:

The calculated point (RT) is the place of possible (probable) location of people, the most critical in terms of position and distance from the sound source (loudspeaker). The RT is selected on the design plane - an (imaginary) plane drawn parallel to the floor at a height of 1.5m.

Requirement for audio signal levels

The basic requirement for the (necessary) sound signal level is set out in the RD:

Sound signals of the SOUE should provide a sound level of at least 15 dBA above the permissible sound level of constant noise in the protected room. Sound level measurement should be carried out at a distance of 1.5 m from the floor level.

Placement Requirements

The main requirement for the placement of loudspeakers is set out in the RD:

Installation of loudspeakers and other voice annunciators (loudspeakers) in protected premises should exclude concentration and uneven distribution of reflected sound.

Taking into account the basic characteristics of loudspeakers

According to , the arrangement of loudspeakers is part of the organizational measures performed in the design of the SOUE and is called electro-acoustic calculation. The most relevant is not just the placement, but the optimal placement of loudspeakers, which allows minimizing the amount of calculated resources (time) and material resources.

Ways of arranging loudspeakers are closely related to their design features. The most generalized is the following classification:

by execution;
by design features;
by characteristics;
according to the method of matching with the amplifier.

Accounting for the type and design features of loudspeakers

By design, loudspeakers can be divided into internal and external. A characteristic feature of the internal design is the IP protection class. For internal loudspeakers, IP-41 is sufficient, for external loudspeakers - not lower than IP-54. For premises, primarily for the sake of economy, internal loudspeakers are used.

Depending on the tasks to be solved, loudspeakers of various designs can be used. So, for example, depending on the configuration of the room, ceiling-mounted or wall-mounted loudspeakers can be used. For scoring open areas, horn loudspeakers are used, due to their characteristics, protection class, high degree of sound directivity, high efficiency.

The specifics of accounting for the main parameters of loudspeakers

To implement a competent placement of loudspeakers, we need the following characteristics (basic parameters) of the loudspeaker:

Loudspeaker Sound Pressure Calculation

Loudspeaker loudness cannot be measured directly, so in practice it is expressed in terms of sound pressure levels, measured in decibels, dB.

The sound pressure of a loudspeaker is determined both by its sensitivity and by the electrical power supplied to its input:

Speaker sensitivity P 0, dB (loudspeaker sensitivity is sometimes called SPL from English. SPL - Sound Pressure Level) - the sound pressure level measured on the working axis of the loudspeaker, at a distance of 1 m from the working center at a frequency of 1 kHz at a power of 1 W.

Loudspeaker power

There are several main types of power:

Loudspeaker Rated Power– electrical power at which the nonlinear distortion of the loudspeaker does not exceed the required values.

Loudspeaker power rating- is defined as the highest electrical power at which the loudspeaker can work satisfactorily for a long time on a real sound signal without thermal and mechanical damage.

Sinusoidal power is the maximum sinusoidal power at which the loudspeaker must operate for 1 hour with a real music signal without suffering physical damage (cf. maximum sinusoidal power).

In general, the value specified by the loudspeaker manufacturer should be used as the power parameter.

Basic calculations

Sound pressure reduction with distance

To calculate the sound pressure level at the calculated point, it remains to determine one more important parameter - the magnitude of the decrease in sound pressure depending on the distance - divergence, Р 20 , dB. Depending on where the loudspeaker is installed - indoors or outdoors, different formulas (approaches) are used.

Calculation of sound pressure level in RT

Knowing the parameters of the loudspeaker - its sensitivity - P 0, dB, the input sound power P W, W, and the distance to the RT, r, m, we calculate the sound pressure level L 1 , dB, developed by it in the RT:

Sound pressure in the RT with simultaneous operation of n loudspeakers:

Effective Range Calculation

The effective sound range of the loudspeaker is the distance from the loudspeaker to the point where the sound pressure does not exceed the value of (LN+15) dB:

Effective sound range (loudspeaker) D, m, can be calculated:

Working with Templates

Let's divide all loudspeakers into three main classes, differing in the direction of emission of sound energy.

Ceiling– loudspeakers, the sound energy of which is directed perpendicular to the calculated plane (floor) [Sound energy is directed along the working axis of the loudspeaker].

wall– loudspeakers whose sound energy is parallel to the calculated plane (floor).

Horn- loudspeakers, the sound energy of which is directed at a certain angle to the calculated plane (floor).

Under patterns we will understand the geometric area, which is the projection of the sound field of the loudspeaker onto the calculation plane:

for ceiling speakers a circle;
for wall - sector;
for horn - ellipse.

The loudspeaker is a wideband device. For the lower frequency of the regulatory range f=200Hz, the loudspeaker can be considered as a sound emitter of a spherical wave. As the frequency increases, the speaker pattern begins to narrow and concentrate inside the spherical cone with the opening angle [Angle between the generatrix of the spherical cone (coverage angle)], determined by the value of the SRP. This representation does not fully correspond to the established practice, according to which the sound field at the loudspeaker output is usually approximated by a semi-ellipse. In it is shown that for (statistically average) SDN=90 0 the quantitative estimates for the cone and ellipse are the same.

Estimation of the effective area sounded by loudspeakers of various types can be associated with the problem of finding the area formed by the intersection of a given spherical cone with the working plane. Let's use a well-known geometric representation, according to which the result of the intersection of a plane and a cone at different angles are various elliptical surfaces - a hyperbola, a parabola, an ellipse and a circle, Fig.1.

Hyperbola is obtained as a result of the intersection of a cone and a plane intersecting one of its generators.

Parabola is obtained as a result of the intersection of a cone and a plane parallel to one of its generators.

Ellipse is obtained as a result of the intersection of a cone and a plane intersecting both of its generators.

A circle is obtained as a result of the intersection of a cone and a plane parallel to its base.

Definition 1

The effective area sounded by the loudspeaker is the area on the working plane within which the sound pressure remains within the limits determined by the loudspeaker radiation pattern.

Let us calculate the effective areas sounded by different types of loudspeakers.

Loudspeaker placement

The problem of optimal placement of loudspeakers can be related to the results obtained in the previous chapter. Let's give a definition:

Definition 2

Loudspeakers must be placed in such a way that any potential design point must fall within the limits covered by the radiation pattern of the nearest loudspeaker.

In the previous section, we got three basic geometric shapes [Which we will later use as tracing paper (figures) to fill (uniformly cover) the surface] - a circle, a sector and an ellipse. The placement problem can be reduced to a uniform coverage [Cf. the problem of “tiling” the surface in mathematics] of the entire working plane.

Accounting for reflections

In practice, the placement of loudspeakers is carried out taking into account reflections from surfaces [Accounting for reflections is very relevant. It should be noted that the so-called. direct sound (sound energy received by the listener in the first 50ms) consists of 80% reflected energy (the so-called primary reflections), and the clarity of perception (which, by the way, as well as intelligibility is not taken into account in the standards) directly depends on the share of the direct diffusion energy of an enclosed space. Within the framework of the elementary EDA (see the previous chapter), it is proposed to take into account no more than one reflection (cf.)].

We will take into account reflections based on the geometric ray theory, in which sound energy is identified with a geometric ray reflected from the surface at the same angle and in the same plane, Fig.2.

When it hits a surface, some of the sound energy is lost. The proportion of absorbed sound energy P abs, dB, can be determined by knowing the absorption coefficient K abs of the surface:

When considering reflections, it is necessary to check the following boundary condition, Fig. 2:

If condition (8) is met, the placement of the loudspeakers can be carried out taking into account reflections.

Most surfaces such as parquet, laminate, wood, concrete practically do not absorb [So, for example, for wooden sheathing at a frequency of 4 kHz, K absorption = 0.11, P absorption = 0.5 dB]. In further examples of speaker placement, as a simplification, we will assume that the sound energy is completely reflected from the surface.

Critical Speaker Spacing

From Fig. 3 it can be seen that the sound in the RT comes from 2 loudspeakers. Knowing the speed of sound in air v=340m/s and the delay time t=0.05s, it is easy to obtain the critical distance Rcr, m, at which the echo becomes possible: Rcr = vt = 340*0.05=17m, where v is speed of sound propagation in air (340m/s).

From Fig.3, the path difference should be:

Depending on the directivity of the loudspeakers and their SDN, the spacing step can be determined geometrically:

Room classification

We will consider two main types of premises:

corridors;
rectangular rooms.

By corridors we mean narrow extended rooms with ratios of length a (m) and width b (m): a/b≥4.

Rooms with a/b ratios

Let's divide the rooms into the following groups:

corridors with low ceilings (height h ≤ 4m);
corridors with high (h > 4m) ceilings;
corridors are narrow (b ≤ 3m);
wide corridors (b > 3m and h ≤ 6m);
medium rectangular rooms (b > 6m and b ≤ 12m);
voluminous rectangular rooms (b> 12m).

Comment:

To determine the numerical value of the proposed coefficients (b, h), the average value of the effective sounding range D (m) was used, which for P db =95dB, VL=60dB, will be ~ 10m and SRP=90 0 .

How speakers are placed, with or without reflections, is determined by two factors:

ceiling height (with high ceilings, the reflection effect can be ignored);
type of reflective surface.

Corridors with low or high ceilings

The concepts of “low / high” ceilings will be considered in relation to the ways in which ceiling speakers are placed.

When placing loudspeakers on low ceilings, it is desirable to take into account reflections from the floor. In this case, the following criterion is used to determine the numerical value of the speaker spacing:

The sound energy emitted by the ceiling loudspeaker should 'finish' to the floor and, reflected from it, to the 'calculated plane'.

When placing loudspeakers on high ceilings, reflections from the floor can be ignored or criterion (8) must be checked.

Narrow or wide corridors

The concept of “narrow / wide” corridors will be considered in relation to the methods of placing both ceiling and wall speakers. In both cases, we will have to take into account reflections from the floor or walls.

For wall speakers

To determine the numerical value of the spacing of the wall loudspeakers in the case of reflections, we will use the following criterion:

The sound energy emitted by the wall speaker should “finish off” to the opposite wall and, reflected from it, to the wall on which the speaker is installed.

When placing loudspeakers in wide corridors, reflections from walls can be ignored or criterion (8) must be checked.

For ceiling speakers

To clarify the meaning of narrow/wide corridors in the case of ceiling loudspeakers, consider the concept of a loudspeaker chain.

Figure 4 shows a wide corridor containing two chains of ceiling speakers.

The number of chains, K c, pcs, will be determined from the ratio:

Consider examples of loudspeaker placement for different types of premises (cases) and the conditions for determining the spacing W, m.

Ceiling speaker placement

Placement of ceiling speakers in corridors with high ceilings without taking into account reflections from the floor

Placement of ceiling loudspeakers in corridors with high ceilings without taking into account reflections [As noted above, due to the height of the ceilings or the presence of reflective surfaces] from the floor, should be carried out in steps, Fig. 5:

With SDN=90 0, R=h–1.5:

Test condition 1

The loudspeaker, taking into account the SDN, must reach the working plane.

With SDN=90 0:

Placement of ceiling speakers in corridors with low ceilings, taking into account reflections from the floor

It is permissible to place ceiling loudspeakers in corridors with low (less than 4m) ceilings, taking into account reflections (from the floor) in increments, Fig. 6:

Arrangement of wall-mounted loudspeakers placed along one wall, ignoring reflections

Placement of wall loudspeakers in (wide, over ~3 m) corridors, with placement along one wall, without taking into account reflections, should be carried out with a step of W=2R:

where ShK is the width of the corridor, Fig.7.

With SDN=90°, R=ShK we have W=2ShK.

Test condition 3

Effective range, for arbitrary SDN:

For SRP= 90°:

Let us write down the criterion for determining the effective range, taking into account the installation height of the loudspeaker, H, m. For an arbitrary SRP:

Arrangement of wall-mounted loudspeakers placed along one wall, taking into account reflections

Arrangement of wall loudspeakers in (narrow, up to ~3 m) corridors, with placement along one wall, taking into account reflections, it is permissible to carry out with a step W=4R, where R is calculated by formula (16), Fig.8.

With SDN=90°, R=ShK we have W=4ShK.

Test condition 4

The loudspeaker, taking into account the SDN, should finish twice to the opposite wall, taking into account the SDN.

Effective range, for arbitrary SDN:

For SRP= 90°, excluding absorption:

Considering the installation height, see formula (18).

Placement of wall-mounted loudspeakers in rectangular rooms, staggered along two opposite walls

The placement of wall-mounted loudspeakers in medium rectangular rooms, with the possibility of placement along two opposite walls, is desirable to be carried out in a checkerboard pattern with a step of W = 2R:

where b is the width of the room, Fig.9.

With SDN=90°, R= b we have W=2b.

Test condition 5

The loudspeaker, taking into account the SDN, should reach the opposite wall.

Effective range, for arbitrary SDN:

For SRP= 90°:

Arrangement of wall-mounted loudspeakers in rectangular rooms, placed along two opposite walls

Wall loudspeakers in rectangular rooms of a large area can be placed on opposite walls, in any order with a step determined by half the distance to the opposite wall, b / 2 (m) W = 2R.

Where b is the width of the room, Fig.10.

With SDN=90°, R= b we have W=b.

Test condition 6

The loudspeaker, taking into account the SDN, should penetrate half the distance to the opposite wall, Fig. 10.

Effective range, for arbitrary SDN:

For SRP= 90°:

The installation height is taken into account similarly to formula (18).

Placement of loudspeakers in rooms with a complex configuration

The placement of loudspeakers in rooms with a complex configuration is carried out as follows. The sounded (designed) room is analyzed, divided into separate sections, for each of which the appropriate arrangement scheme is selected, from the above. The main task, in this case, is reduced to the optimal docking of individual sections.

Literature

Code of Rules SP-3-13130-2009 of 2009 “Fire safety requirements for sound and voice warning and evacuation management”.
Kochnov O.V. “Peculiarities of designing warning systems” (Murom, publishing house Kovalgin, 2012).
Kochnov O.V. “Design of warning systems” (Tver 2016, Volume 1).

Timely informing about the outbreak of a fire helps to effectively carry out the evacuation of people and begin prompt measures to eliminate the source of fire. This is especially true for buildings in which a significant number of people live or work. For these purposes, alerts are used.

One of the varieties of such equipment is a light and sound annunciator, where light and sound are used to transmit an alarm signal. With its help, fire and security systems are equipped, which are responsible for the prompt evacuation of people in the event of a threat to their lives.

Main functions of the device

A light and sound annunciator is a complex electronic device that sends both visual and audible alarm signals. Almost all modern security and fire alarm systems are equipped with such devices, which are responsible for the prompt evacuation of people when the first signs of danger appear.

As a rule, sirens are installed at the following objects:

educational and medical institutions;
retail outlets and entertainment centers;
catering facilities;
hotels;
industrial buildings and structures.

The advantage of light and sound signaling is the use of a duplicated signal to warn of danger. This allows you to attract as much attention as possible when there is a lot of smoke, or when the building is very noisy.

Often devices are placed in an explosion-proof case, which contributes to their uninterrupted operation in fire conditions. There are intrinsically safe models designed for installation in hazardous areas, and devices in the usual version.

Design features

Red and yellow light is used to signal danger in light and sound annunciators, blue and green colors can be additionally provided. The glow can be both flashing and constant. The sound mode and nature of the sound signal may also vary depending on the model of the device.

A modern light and sound annunciator consists of several modules:

high-strength metal shell capable of resisting aggressive influences;
a board made of reinforced glass for light informing with inscriptions “exit”, “powder leave”, “do not enter” and others (there may not be any inscriptions);
a source of sound pulsating signals having a certain sound spectrum and a sound level of at least 85 dB;
special connectors that make it possible to switch the wiring of the system.

The design of the light and sound annunciator is thought out in such a way that it can continue to work in the mode of extreme and aggressive influences. To prevent unauthorized openings, the device is equipped with a special access contact. There are special mounting holes and openings for power and control cables.

Installation

Due to the extensive warning coverage area, light and sound equipment is most often mounted on walls and other building structures. This allows you to achieve the greatest visual and acoustic coverage of the surrounding space.

It is important to do everything possible so that there are no obstacles in the directions of the sound waves, and the human eye can clearly perceive the inscriptions on the scoreboard or light indication in both natural and artificial lighting conditions.

The specifics of the installation of light and sound signaling equipment is influenced by its type, place of application and type of housing.

Wireless devices are more convenient in this regard: their installation includes a simple mounting of the base, while other parts are on the board under the cover. If the siren is powered by a cable, then special channels will have to be used for its installation. If the alarm is set up outdoors, it is recommended to place the wiring inside corrugated metal pipes. To ensure that the operation of the device is not affected by precipitation, protective visors are used.

Popular Models

On sale light and sound explosion-proof annunciators are presented in a wide range. Considering the fact that a person's life directly depends on their work, it is better to give preference to proven models, with an optimal price / quality ratio. The higher the protective properties of the case, the wider the capabilities of the device, the higher its price, which can reach 8-10 thousand rubles.

Mayak-12-KP

The purpose of this combined fire and security device is to alert people about the danger that has arisen by means of sound and light signals.

Assembly and maintenance work may only be carried out if there is adequate experience.

This light and sound annunciator is not intended for operation in hazardous areas. During installation, it is important to ensure reliable protection of equipment from climatic and atmospheric influences.

Mayak-12-KP has a sound pressure level of 105 dB. The disadvantages of the device is the inability to change the volume level. In cases where the signal strength is not enough, it can be amplified with a howler. The body material is steel. The siren has a compact size and modern design. It is allowed to operate the equipment in temperature conditions from -30 to +55 degrees.

Lightning-12-3

This siren looks like a sign with the word "Exit" on a red or green background. The convenience of this device lies in its ability not only to signal the start of a fire, but also to indicate the direction of evacuation. The beep volume is set to 100 dB.

The collapsible scheme makes it possible to install any inscription on the scoreboard. For the manufacture of the case, polycarbonate is used with a transparent insert in front of acrylic glass.

The correct operation of the light and sound annunciator "Lightning-12-3" is guaranteed at temperatures from -30 to +55 degrees. To simplify installation, the body of the device is provided with special holes. This allows surface mounting on the wall surface. The light source is an LED-type ruler that illuminates the scoreboard on a volumetric scale.

The device requires a 12V or 24V DC power source to function.

For switching with external sources, the siren has a special terminal block.

Visual and light warning can work in parallel or separately, the device operation mode is set depending on the operating conditions.

Biya-S

The light and sound type siren of the Biya brand provides an acoustic pressure level of 85 dB, and is capable of continuously sending alarm signals throughout the day.

For power supply, an alternating voltage of 220 V and 50 Hz is used, light signals are sent by an electric lamp with a power of 25 W. Sound notification is provided by an electrodynamic circuit operating at temperatures from -40 to +50 degrees and air humidity up to 98%.