EN 54-24 Fire Detection and Fire Alarm Systems - Part 24: Components of Voice Alarm Systems - Loudspeakers

A European standard, “EN 54-24 Fire detection and fire alarm systems - Part 24: Components of voice alarm systems - Loudspeakers”, describes the requirements, test methods and performance criteria for loudspeakers designed to broadcast a fire warning to occupants of a building through a fire detection and fire alarm system.

This standard specifies loudspeakers for two types of application environments: type A, generally for indoor use, and type B, generally for outdoor use. This standard does not cover loudspeakers for special applications, such as loudspeakers for use in hazardous applications, if such applications require additional or other requirements or tests than those given in this standard. This standard is not intended to cover addressable loudspeakers, active component loudspeakers. Voice alarm sounders are covered in "EN 54-3 Fire detection and fire alarm systems - Part 3: Fire alarm devices - Sirens".

For the purposes of this standard, in addition to the terms and definitions given in EN 54-1, the following definitions apply:

• 1/3 octave refers to the frequency band defined in the EN 61260 standard.
• The angle of coverage is the smallest angle between two directions on either side of the reference axis. The sound pressure level is 6 dB less than the sound pressure level on the reference axis. This angle is measured in the vertical and horizontal planes.
• The free field condition is the acoustic environment in which sound pressure decreases with distance from a point source, the region that the sound field between the speaker system and the microphone will occupy during measurements with an accuracy of plus or minus 10 percent. For example, an anechoic chamber, a quiet outdoor area.
• The frequency response is the sound pressure level produced in the 4/100 octave frequency bands between 10 Hz and 1 kHz (center frequencies) at a distance of 3 m from a reference point on the reference axis. It is also called the magnitude or amplitude response.
• Ground plane measurement is the measurement under half-space free field conditions used to simulate the free field condition, where the loudspeaker is mounted on a completely acoustically reflective boundary surface and the reference axis is aimed directly towards a measurement microphone placed on the boundary surface. To obtain measurement results comparable to the free field condition, ground plane measurements need to be corrected by -6 dB at all frequencies.
• The half-space free field condition is an acoustic environment bounded by a plane of sufficient size and in which the free field is contained within a hemisphere such that the sound pressure from a point source mounted on the surface of that plane is reduced, for example a half-space anechoic chamber.
• The horizontal plane is the virtual plane of the speaker containing the reference axis as specified by the manufacturer.

In this standard, the requirements are defined as follows:

• Compliance: To comply with this standard, voice alarm loudspeakers must meet the requirements of this clause, which shall be verified by visual inspection or engineering judgment, be tested as described in this standard, and meet the requirements of the tests.
• Frequency response limits: The loudspeaker frequency response must fit within the unshaded area shown in the figure given in the standard. If the frequency response shown in the figure can only be achieved by means of a frequency equalizer specified by the manufacturer for normal use, it is acceptable to install a special equalizer in the measurement setup.
• Durability: The audible alarm speaker should be rated for at least 100 hours of operation at the rated noise power specified by the manufacturer.
• Construction: The loudspeaker shall provide space within the enclosure for external conductors to be brought in and terminated. Entry holes for conductors or cables shall be provided or indicated by a template or other suitable means. Terminals used to connect external conductors shall be designed to be clamped between metal surfaces without damage. Each terminal shall permit the connection of any conductor having a cross-sectional area between 0,8 mm2 and 2,5 mm2.
• Materials: The loudspeaker must be made of materials that can withstand the tests specified in this standard. In addition, the materials of the plastic enclosures must comply with their specified requirements.
• Enclosure protection: The degree of protection provided by the enclosure of fire alarm loudspeakers must comply with the specified requirements.
• Access: Means must be provided to limit access for removal of parts or the entire device and to make adjustments to the operating mode, e.g. special tool, codes, hidden screws, gaskets.
• Marking: Each audible alarm loudspeaker shall be clearly marked with the information specified in this standard. If any markings on the device use symbols or abbreviations that are not commonly used, these shall be explained in the data accompanying the device. The marking need not be noticeable when the device is installed and ready for use, but shall be visible during installation and accessible during maintenance. Markings shall not be placed on screws or other easily removable parts.
• Information in the product data sheet: the information required by this standard must be provided with the device or given in a data sheet or technical manual specified on or with each device.

The test methods defined in this standard include:

• Repeatability
• Rated impedance
• Horizontal and vertical coverage angles
• Maximum sound pressure level
• Nominal noise power (durability)
• Dry heat (work)
• Dry heat (endurance)
• Cold (work)
• Moist heat, cyclic (work)
• Damp heat, steady state (durability)
• Damp heat, cyclic (durability)
• Sulfur dioxide (SO2) corrosion (durability)
• Shock (operational)
• Impact (operational)
• Vibration, sinusoidal (operation)
• Vibration, sinusoidal (durability)
• Enclosure protection

Our organization, which has been trying to support businesses from every sector with its testing, measurement, analysis and evaluation studies carried out in a wide range for years, has a strong staff that closely follows the developments in the world in the field of science and technology and constantly improves itself. In this context, testing services in accordance with the "EN 54-24 Fire detection and fire alarm systems - Part 24: Components of voice alarm systems - Loudspeakers" standard are also provided to businesses.