As we continue our "let's learn" series, we look at BS 476 Part 22.
What is BS 476 Part 22?
BS 476 Part 22 is a key standard within the UK's building safety regulations that specifies methods for testing the fire resistance of non-loadbearing elements of construction, such as doors, shutters, and various types of ducts and dampers. This standard is instrumental in determining how these elements will perform in the event of a fire, ensuring they meet the necessary safety requirements to protect building occupants and property.
What is the Scope of BS 476 Part 22?
The scope of BS 476 Part 22 covers the testing procedures for assessing the fire resistance of any non-load-bearing components of a building when exposed to specific heating and pressure conditions as detailed in BS 476 Part 20. The standard includes detailed observation of the specimen’s behaviour under test conditions, including the manner and timing of failure, if applicable. This comprehensive approach helps in understanding the effectiveness of building components in fire conditions.
How do we test for BS 476 Compliance?
Testing for BS 476 compliance involves several key steps:
Placement of Specimen: The non-load-bearing element to be tested is placed in a furnace designed to replicate fire conditions.
Heating Conditions: The temperature within the furnace is increased following a predefined time-temperature curve to simulate real fire conditions.
Monitoring: Throughout the test, the integrity and insulation performance of the specimen are closely observed.
Recording: Observations and measurements are meticulously documented, including any structural changes or failures.
What test procedures do we use?
The test procedures for BS 476 Part 22 compliance are centered around simulating fire-like conditions in a controlled environment using specific equipment:
● Furnace: Capable of reaching up to 1200 degrees Celsius, mimicking the intense heat of a fire.
● Temperature Measurements: Devices are used to ensure the testing conditions adhere strictly to the specified criteria.
● Observational Assessments: The specimen's ability to maintain structural integrity and insulate against heat is critically assessed throughout the test duration.
What is the Criteria for success?
The criteria for a successful BS 476 Part 22 test are based on two main parameters:
● Integrity: The ability of the specimen to prevent the passage of flames and hot gases.
● Insulation: The capability of the specimen to limit the temperature rise on the non-exposed surface to below specified thresholds.
Additionally, the irradiance is monitored using a radiometer in alignment with BS 476-20 standards. A product is considered to have passed the test if it meets both the integrity and insulation criteria under the defined testing conditions.
The government has recently confirmed that the withdrawal of the national classes of fire testing standards in England will come into force on the 2nd March 2025. The European standard (BS EN) will be the sole route of specification within Approved Document B for reaction to fire from March 2025 with references to BS 476 associated with fire resistance to be withdrawn on 2nd September 2029.
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