Author: Zhang Yulin
Source: Building and Culture, Issue 07, 2024
Abstract: This article analyzes the general concepts and common types of fire doors, conducting tests to evaluate their fire resistance. It concludes that the primary factor affecting fire door performance is the internal filling material. The article ranks various types of fire doors based on their fire resistance, providing valuable insights for production and application.
Keywords: Fire door, types, fire resistance
Introduction
As China’s economy rapidly develops, significant changes have occurred in residential and public building construction over the past thirty years. Historically dominated by low-rise buildings, the shift towards high-rise structures has increased population density and, consequently, heightened fire safety standards. In the event of a fire, the ability to contain flames and provide escape time is critical—especially in densely populated residential areas and large public spaces. Effectively blocking the spread of fire can significantly reduce casualties and property damage.
Fire door are recognized as effective passive fire protection devices. During a fire, they contain high temperatures and smoke within designated areas, preventing rapid fire spread. Thus, the fire resistance performance of Fire exit doors is vital in emergency rescue situations.
Understanding Fire Doors: Concepts and Classifications
According to GB/T 9978.1-2008, fire doors are classified based on their fire resistance capabilities, as specified in GB 12955-2008.
- Types of Fire Door:
- Closed Fire Doors: Typically remain closed and can be opened by pushing. Comprising a door leaf, frame, closer, sequence control, fire lock, and hinges, closed fire doors are simple in structure and low-cost, requiring minimal maintenance. Over 90% of Flame-resistant doors in China are of this type.
- Open Fire Doors: Normally remain open and automatically close during a fire. These doors include components such as electromagnetic release valves and central control systems, functioning through a series of alerts from fire detection systems.
- Material Composition:
- Steel Fire Doors: Constructed with steel frames and panels, filled with non-toxic fire-resistant materials.
- Wooden Fire Doors: Made from fire-retardant wood or wood products, also filled with non-toxic fire-resistant materials.
- Steel-Wood Composite Fire protection doors: Combine steel and fire-retardant wood materials.
- Fire Resistance Classification:
- Fire doors are categorized as A (insulated), B (partial insulation), or C (non-insulated) based on their thermal performance.
Guangdun Door Industry Co., Ltd., as a leading player among fire door manufacturers, emphasizes the importance of academic rigor and technical expertise in producing high-quality fire rated doors. This understanding of fire door classifications and materials underpins our commitment to safety and reliability in building designs.
Fire Resistance Performance of Wooden and Steel-Wood Composite Fire Doors
Wooden fireproof door are constructed using fire-retardant wood or wood products for the frame, door leaf skeleton, and door panels. When filled, these Heat-rated door utilize non-toxic fire insulation materials and include fire-rated hardware, providing a certain level of fire resistance. Steel-wood composite fire doors combine steel and fire-retardant wood materials in their construction, also filled with non-toxic fire insulation and equipped with fire-rated hardware to ensure flame resistance.
Types of Fire-resistant doors Based on Fire Resistance
According to GB 12955-2008,Fire safety doors can be classified into three categories based on their thermal performance:
- Type A (Insulated Fire Doors): Provide full thermal insulation.
- Type B (Partial Insulated Fire Doors): Offer limited thermal insulation.
- Type C (Non-Insulated Fire Doors): Provide no thermal insulation.
Technical Requirements for Fire Doors
Table 1 outlines the technical requirements for flame-rated doors classified by heat resistance according to GB 12955-2008. The criteria for determining fire resistance limits include:
- Testing Conditions: The relationship between furnace temperature (T) and time (t) is defined as T = 345 log(8t + 1) + 20, where T is the average temperature in degrees Celsius, and t is the time in minutes. Pressure conditions in the furnace must also meet specific criteria.
- Fire Resistance Assessment: During the prescribed testing duration, doors must meet the following requirements:
- Integrity: The door must not lose integrity, which includes preventing flames from burning on the back surface for longer than 10 seconds and ensuring that flames do not ignite a cotton pad.
- Thermal Insulation: The average temperature rise on the back surface must not exceed 140°C, and any point on the back surface must not exceed an initial temperature of 180°C.
Experimental Overview
Fire resistance (also referred to as fire limit) encompasses both thermal insulation and structural integrity. Thermal insulation is the capacity of a building component to maintain temperatures below specified limits on the non-fire side during a standardized test. Structural integrity refers to the ability to prevent flames and hot gases from penetrating or appearing on the non-fire side during a defined time frame.
This study adheres to GB/T 9978.1-2008 and GB 12955-2008, testing various fire rated door and analyzing results. The temperatures reported are adjusted for environmental conditions at the start of the tests.
- Testing of Steel Fire rated Door: A steel fire door filled with perlite was tested according to A1.50 (Class A). Data indicated the relationship between standard and average furnace temperatures over time.
- Testing of Wooden Fire-rated Door: A wooden fire door, also filled with perlite and tested under similar conditions, showed comparable results in terms of temperature dynamics.
- Comparison with Other Materials: Tests were conducted on fireproof doors with identical external materials filled with rock wool and glass wool. The steel door filled with glass wool showed a maximum back temperature of 248.5°C after 56 minutes, while the rock wool door exceeded 180°C at 77 minutes.
Results and Analysis
The maximum back surface temperatures recorded were 116.9°C for the wooden fire door and 132.3°C for the steel fire door, both showing average maximum temperatures below 140°C and significantly below 180°C. Throughout the testing, neither door type experienced collapse, burning through, or flame penetration on the back surface, meeting the A1.50 (Class A) fire resistance requirements. The outer materials of both door types had minimal impact on their fire resistance performance.
In conclusion, both wooden and steel-wood composite Fire-rated entry door exhibit effective fire resistance, showcasing the importance of material selection and construction quality in the fire door manufacturing process. As a reputable flame door manufacturer, Guangdun Door Industry Co., Ltd. remains committed to producing high-quality Combustion-rated door that meet rigorous safety standards.
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