Smoke exhaust ducts are core facilities in building fire protection systems, playing a crucial role in removing fire smoke, heat, and harmful gases. The standardization of their design, installation, and maintenance is directly related to personnel evacuation, property protection, and building safety. The following is a comprehensive analysis of smoke exhaust ducts, covering functions, design standards, installation specifications, and maintenance key points.

 

 I. Core Functions of Smoke Exhaust Ducts

There are essential differences between smoke exhaust ducts and ordinary ventilation ducts:

1. Emergency Smoke Exhaust: Quickly remove smoke and high - temperature gases during a fire, delay the spread of the fire, and buy time for personnel evacuation.

2. Daily Smoke Exhaust: Continuously remove cooking fumes and harmful gases in places such as kitchens and factories to improve air quality.

3. Safety Assurance: Prevent smoke accumulation from causing suffocation or secondary disasters and reduce fire losses.

 

 II. Design Standards: Material, Structure, and Performance Requirements

1. Material Selection:

   - Metal Materials: Mainly stainless steel and galvanized steel sheets, which are resistant to high temperatures (≥280°C) and corrosion and suitable for long - term use.

   - Non - metal Materials: Fiberglass, ceramics, etc., which are resistant to acids and alkalis and lightweight, suitable for special environments.

   - Fire - resistance Requirements: The ducts need to maintain structural integrity at a high temperature of 280°C for at least 30 minutes. The fire - resistance limit of the smoke exhaust duct in the shaft should not be less than 0.5 hours.

2. Structural Design:

   - Layout Principle: Set up independently to avoid crossing with gas pipelines; vertical ducts should be placed in dedicated shafts, and the fire - resistance limit of the shaft partition wall should be ≥1 hour.

   - Wind Speed Control: The wind speed in metal ducts should be ≤20m/s, and in non - metal ducts ≤15m/s to ensure smoke exhaust efficiency and reduce noise.

   - Cross - sectional Size: Determined by calculating the smoke exhaust volume, usually designed with a smoke exhaust volume per unit area ≥60m³/(h·㎡).

 

 III. Installation Specifications: Classification and Construction Key Points

1. Installation Types:

   - Vertical Type: Installed vertically on the roof, suitable for high - rise buildings.

   - Side - wall Type: Extended horizontally on the outer wall, commonly seen in low - rise buildings or industrial workshops.

   - Centralized Type: Multiple systems connected in parallel, used in large complexes.

2. Key Requirements:

   - Sealing: Fire - resistant gaskets should be used for flange connections, and the bolt spacing should be ≤150mm to prevent smoke leakage.

   - Hoisting Specification: When installing horizontal ducts in the ceiling, the distance from combustibles should be ≥150mm; without a ceiling, the fire - resistance limit should be ≥1 hour.

   - Fire - compartment Treatment: The fire - resistance limit of the ducts passing through fire compartments should be ≥1 hour, and fire dampers should be installed.

 

 IV. Maintenance Management: Ensuring Long - term Reliable Operation

1. Regular Cleaning: Remove oil stains and dust every quarter to prevent blockage (especially in catering establishments).

2. Component Inspection:

   - Conduct linkage tests between valves and fans at least once a month.

   - Check the tightness of the bolts at the connections to avoid loosening and smoke leakage.

3. Fire - resistant Layer Maintenance: Regularly detect the integrity of fire - proof coatings or wrapping materials and repair damaged areas in a timely manner.

4. Emergency Drills: Test the response speed of the smoke exhaust system in combination with fire drills, record faults, and make corrections.

 

 V. Common Mistakes and Optimization Suggestions

1. Mistake: Mixing smoke exhaust ducts with ventilation ducts, resulting in cross - contamination.

   Solution: Set up independent duct systems, and the distance between the smoke exhaust outlet and the air supply outlet should be ≥5 meters.

2. Mistake: Ignoring the sealing of the duct shaft, causing the chimney effect.