FIRE-RESISTANT AIR DUCT

QCVN 06:2021/BXD national technical regulation on fire safety for houses and works. Issued on May 19, 2021, Effective from July 5, 2021.

Section 9 Appendix D – The pipes and equipment of the smoke extraction system must be made of non-combustible materials with fire resistance limits. The pipes and equipment of the smoke extraction system must be made of non-combustible materials with a fire resistance limit of not less than:

- EI 120 - for smoke pipes and ducts located outside the range of the combustion chamber that the system serves; then, at positions where pipes and smoke channels pass through walls and floors of the fire compartment, normally open fire prevention valves must not be installed;

- EI 60 - for smoke pipes and ducts within the scope of the serviced combustion chamber, when used to exhaust smoke from enclosed garages;

- EI 45 - for vertical smoke pipes and ducts within the scope of the serviced combustion chamber, when smoking products of combustion directly in that service area;

- EI 30 - for other cases within the fire compartment serviced.

According to the provisions of the law through Decree No. 136/2020/ND-CP and QCVN 06:2021/BXD, standards of fire-resistant duct systems (or fire-resistant ducts) are applied in fire protection systems have been changed a lot, to ensure safety and quality when put into the project. In particular, flame retardant materials applied in ducts need to ensure fire resistance regulations, especially different EI standards. Or to put it more simply, the EI fireproof duct is a duct system that needs to ensure certain fire resistance limits. Specifically: EI 30; EI 45; EI 60; EI 90 and EI 120, …Equivalent to fire resistance thresholds of 30 – 45 – 60 – 90 and 120 minutes.

According to the QCVN06:2020 standard on fire safety for houses and buildings, Fire rated ductwork is tested according to ISO 6944:1985. Determined how fire test has different criteria. Standards for fire-resistant ductwork are classified into two categories.

• Duct type A: for fire outside the duct
• Duct type B: for fires inside ducts

The fire resistance of the duct system is expressed in minutes from the time of heating until the failure occurs.

In the regulations on firefighting, the EI standard is a set of standards that regulate the fire resistance limit of fireproof materials. This fire resistance limit is determined in units of time. The duration of fire resistance of a flame retardant material is determined by a standard heating test. This period is calculated from the beginning of the experiment, the temperature is gradually increased from 0 - 1500 * C. Until the appearance of one or more signs simultaneously with the limits specified as follows:

• Material integrity limits

E (Integrity) is the limit at which the structure of the material is perfectly maintained without breaking, falling, etc., regardless of the heat transfer capacity of the material. This limit is usually determined for application in fireproof solutions such as the production of partitions, walls, ventilation systems, etc.

• Limits on thermal insulation

I (Thermal Insulation) is the limit at which the material retains its thermal stability, the main structure of the material is not damaged by heat. Determine this limit to apply to solutions to prevent fire spreading such as fireproof walls, fireproof paints, and fireproof partitions to ensure when a fire occurs. The materials are kept intact, the fire cannot spread, the temperature at the surfaces of the materials is guaranteed.