Smoke exhaust valves and fire dampers quality requirements for engineering applications

1. The primary uses of fire dampers and smoke dampers

High-rise buildings and other modern structures typically feature ventilation, air conditioning, and smoke control systems. In the event of a fire, these systems' ducts can become pathways for the spread of flames and smoke. To prevent the fire from spreading through the air ducts, both the "Code for Fire Prevention in Building Design" GBJ16-87 and the "Code for Fire Prevention in Design of High-Rise Civil Buildings" GB50045-95 explicitly specify the requirements for the installation of fire dampers and smoke exhaust valves.

Fire dampers are used in the supply and return air ducts of ventilation and air conditioning systems, remaining open at all times. Upon the occurrence of a fire, they automatically close when the gas temperature inside the pipes reaches 70°C, and can maintain fire resistance and integrity for a certain period, serving as a smoke and fire barrier. Smoke exhaust valves are installed on the pipes of the smoke exhaust system or at the intake of smoke exhaust fans, and are normally closed. In the event of a fire, they are manually or automatically opened via a fire alarm signal, working in conjunction with the system to exhaust smoke. They automatically close when the smoke temperature inside the pipes reaches 280°C, and can also maintain fire resistance and integrity for a certain period, acting as a smoke and fire barrier.

2. The crucial role of fire dampers and smoke exhaust valves in ventilation, air conditioning, and smoke control systems

Fire dampers include various products such as gravity-operated fire dampers, fire regulating dampers, fire air inlets, pneumatic fire dampers, smoke and fire dampers, and electronic self-control smoke and fire dampers; smoke exhaust dampers include smoke exhaust fire dampers, plate-type smoke exhaust outlets (for ceilings), and smoke exhaust outlets for shafts. Fire dampers and smoke exhaust dampers are important components in ventilation, air conditioning, and smoke and exhaust control systems, and play a crucial role in the system in the following three aspects:

2.1 Fire and smoke barrier effect

In the air distribution system, the air supplied by the fan must be distributed through the main duct to the branch ducts; in the smoke exhaust system, smoke flows from the branch ducts to the main duct before being exhausted by the exhaust fan. When a fire occurs within the building, to prevent the fire from spreading through the air distribution system, when the gas temperature in the air distribution system reaches 70°C, the fuse on the fire damper mechanism operates, and the valve closes rapidly, cutting off the path for the spread of smoke and fire along the ducts. Similarly, in the smoke exhaust system, when a fire occurs, the smoke exhaust valve opens to exhaust smoke. To prevent the spread of fire to another fire compartment by the high-temperature smoke, when the temperature of the exhaust smoke reaches 280°C, the fuses on the smoke exhaust fire damper and smoke exhaust outlet activate, and the valves must automatically close to prevent smoke exhaust. Thus, the fire damper and smoke exhaust valve effectively perform their functions of allowing passage when necessary and blocking smoke and fire when required.

2.2, Adjusting Function

In the design of ventilation and air conditioning system pipelines, even though calculations are made, if the operating conditions of the actual project change, adjustments must be made to the air volume of each system component through fire damper valves. Conduct system debugging, set the valve openings, allocate them reasonably, to meet the design requirements.

2.3. Start No-load Operation

All centrifugal fans and fire exhaust axial flow fans in ventilation air conditioning and smoke exhaust systems are generally started with no load for safety during installation and commissioning. This is achieved by temporarily blocking the pipeline through valves to reduce the motor's starting current.

3. Quality Requirements for Engineering Applications

3.1 Quality Requirements

Currently, there are many manufacturers of fire prevention and smoke exhaust product series. Our fire supervision, construction review, and design departments should strictly screen to ensure that the client selects products with complete "three certificates" and meet the required standards, including the manufacturer's product qualification certificate, the public security fire department's product sales permit, and the product inspection report from the Fireproof Building Material Quality Supervision and Inspection Center. The product performance and quality can be reflected from the inspection report and technical parameters, which are based on the national standards "Fire Damper Test Method" GB15930-1995 and "Smoke Exhaust Fire Damper Test Method" GB15931-1995. The quality requirements of the products are manifested in five aspects:

3.1.1 Temperature Sensor Actuation Performance Test

The temperature-sensitive elements of fire dampers and smoke dampers are separately tested at the specified temperatures of constant-water bath and oil bath. Through non-operation and operation tests, their ability to accurately close at the required temperature is verified.

3.1.2 Disable Reliability Test

The specimen should be able to close from the open position flexibly and reliably after 250 closures on the test bench, with no obvious wear, deformation, or damage affecting its sealing performance. This is to test the reliability of the closure.

3.1.3 Salt Spray Test

The test piece is subjected to salt spray testing in a salt spray chamber. The test piece should be able to close reliably from the open position, thereby verifying the valve's corrosion resistance in actual engineering applications.

3.1.4 Air Leakage Test

Under the specified pressure difference conditions, the air leakage rate per unit area of the test piece shall not exceed 700 Nm³/(h·m²) to verify the sealing performance of the valve after it is closed.

3.1.5. Fire Resistance Test

Through耐火试验, based on the valve's closing ability within the specified time and the air leakage rate per unit area, determine the fire resistance of the valve.

Additionally, the technical specifications of the product require a耐火limit of 3 hours.

3.2 Installation Quality Requirements

During routine fire prevention inspections and project acceptance, I've found issues such as poor installation quality causing smoke exhaust valves to malfunction or fail to open properly, difficulties in resetting smoke exhaust valves, exhaust openings, fire dampers, and fire-protected air inlets. This should prompt contractors to pay attention to the following installation requirements.

3.2.1 Fire dampers and smoke valves should be installed strictly according to the drawings, with independent support and suspension brackets to prevent the air ducts from deforming under high temperatures, which may affect the valve function.

3.2.2 When valves are installed on the ceiling or within the duct, a maintenance access hole should be provided on the ceiling panel or the duct wall. Generally, the access hole size should not be less than 450×450mm. In cases where conditions are limited, the ceiling maintenance hole can be reduced to 300×300mm.

3.2.3 The air duct between the fire damper and the fire wall (or floor) should be made of steel plate with a thickness of δ≥1.5mm. It is also recommended to insulate and isolate the air duct externally with fire-resistant materials or use non-combustible materials for protection to ensure the fire-resistant performance of the fire wall.

3.2.4 There should be a clear space of 350mm on the mechanical side of the valve for ease of maintenance.