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IS 928:1984 is the Indian Standard (BIS) for fire bells. This standard lays down the requirements regarding materials, dimensions, construction, and performance criteria for fire bells used to sound alarms during fire emergencies. It is utilized by fire safety engineers and manufacturers to ensure reliable mechanical or electromechanical warning systems.
! While modern electronic fire alarm sounders are more common, mechanical fire bells are still specified in certain heavy industrial applications due to their rugged durability and distinct frequency.
! Ensure that the material used for the gong matches the environmental conditions (e.g., highly corrosive environments) to prevent rusting, which can severely dampen the acoustic output.
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International Equivalents
Similar International Standards
EN 54-3:2014+A1:2019CEN (European Committee for Standardization), Europe
HighCurrent
Fire detection and fire alarm systems - Part 3: Fire alarm devices - Sounders
Covers performance requirements and testing for all fire alarm sounders, including electromechanical bells.
UL 464, 11th EditionUnderwriters Laboratories (UL), USA
HighCurrent
Audible Signaling Devices for Fire Alarm and Signaling Systems, Including Accessories
Specifies requirements for audible devices like bells, horns, and speakers used in fire alarm systems.
ISO 7240-3:2017ISO (International Organization for Standardization), International
HighCurrent
Fire detection and alarm systems — Part 3: Audible alarm devices
Defines international requirements and test methods for audible alarm devices in fire detection systems.
Key Differences
≠IS 928:1984 specifically includes requirements for manually operated (rotary and pull-lever) fire bells, a category not covered by modern international standards like EN 54-3 or UL 464, which focus on electrically powered devices within an automated system.
≠International standards mandate extensive environmental and EMC (Electromagnetic Compatibility) testing, including resistance to damp heat, corrosion, impact, vibration, and radiated/conducted emissions, which are absent in IS 928:1984.
≠EN 54-3 and ISO 7240-3 require detailed characterization of the sound output, including measuring the sound pattern in multiple axes (polar distribution) and frequency spectrum analysis. IS 928 only requires a simple minimum decibel reading at a single point.
≠Modern standards like EN 54-3 specify system integration requirements, such as line monitoring for open and short-circuit faults, which are not addressed in IS 928.
Key Similarities
≈All standards share the fundamental objective of specifying a device that produces a loud, recognizable audible signal to warn occupants of a fire.
≈Both IS 928 and its international counterparts mandate a minimum sound pressure level (SPL) at a specified distance (e.g., 3 meters) to ensure audibility over typical ambient noise.
≈The requirement for the device to be predominantly colored 'Fire Red' is a common feature across all standards to ensure easy visual identification as a piece of fire safety equipment.
≈All standards require the device to pass an endurance test, involving a significant number of operational hours or cycles, to demonstrate its reliability and durability over its expected service life.
Parameter Comparison
Parameter
IS Value
International
Source
Minimum Sound Output (at 3m)
≥ 90 dB(A) for electric bells (150mm gong and above)
≥ 85 dB(A), often adjustable; performance is specified relative to manufacturer's stated level.
UL 464
Operating Voltage Range (Nominal 24V DC)
20.4V to 26.4V (-15% to +10% of 24V)
16V to 33V DC (a much wider range to accommodate system fluctuations)
EN 54-3
Enclosure Protection
General requirement to be 'suitably protected against dust and moisture', no specific IP rating.
Must be tested to a specific IP Code (e.g., IP21C for indoor, IP33C for outdoor) depending on type.
EN 54-3
Endurance Test (Electric)
100 hours of continuous operation at rated voltage.
500 hours of cyclic operation under varying environmental temperatures (e.g., 1 hour on, 1 hour off).
UL 464
Gong Material
Prescriptive: Specifies 'Cast iron, cast steel or brass'.
Performance-based: Any material can be used as long as the device passes all performance, environmental, and durability tests.
EN 54-3 / UL 464
Device Marking
Basic details: Manufacturer, voltage, current, gong diameter.
Extensive details: Model, date code, voltage range, current, sound level, environmental type, IP rating, and standard number.
EN 54-3
⚠ Verify details from original standards before use
Key Values2
Quick Reference Values
Nominal gong sizeTypically 250 mm
Minimum sound levelUsually 65 dB to 90 dB depending on operating distance
It specifies the standard construction, materials, and testing parameters for traditional hand-operated or electromechanical fire bells.
Are mechanical fire bells still relevant under modern codes?+
Yes, they are still used in specific industrial, marine, or hazardous environments, or as manual backups where modern electronic sounders might fail or be unsuitable.