Fire Resistance Properties of Magnesium Oxide (MGO) Boards
Apr 03, 2026
Magnesium oxide (MGO) boards are premium fireproof building materials, classified as Class A1 non-combustible (the highest fire rating). They deliver excellent fire protection through three core mechanisms: inorganic composition, dehydration & heat absorption, and dense structural stability, achieving a fire resistance duration of 1 to 4 hours. No toxic smoke, molten drips or flame spread occur, fully meeting high-standard fire safety regulations.
1. Combustion Performance Rating
Chinese Standard (GB 8624-2012): Class A1 Non-combustible
No ignition or persistent flame at 750°C for 30 minutes
Total calorific value: ≤ 1.5 MJ/kg (negligible combustion energy)
Smoke toxicity: Class ZA3 safe level (FED ≤ 0.5)
No molten drips or flame propagation
High-temperature resistance:
Remains non-flammable, non-shrinking and non-cracking at 800°C
No open flame, only slight carbonization at 1200°C
Melting point of magnesium oxide (MgO): 2852°C, with extreme structural stability
2. Core Fireproof Principles (Three Flame-Retardant Mechanisms)
Inherently Non-combustible Inorganic FormulaBase materials: Magnesium oxide & magnesium chloride (fully inorganic); Reinforced with alkali-resistant fiberglass mesh. No organic combustible substances, eliminating fire risks fundamentally.
Dehydration & Heat Absorption for Cooling & Fire BlockingCrystal water releases under high temperature with endothermic reactions, absorbing massive heat from fire scenes. Water vapor forms an insulating layer to isolate oxygen and flames.
Structural Stability at Extreme TemperaturesSolidified into dense 3D magnesium oxychloride crystal structures. Fiberglass reinforcement prevents cracking and peeling under high heat, maintaining structural integrity, thermal insulation and load-bearing capacity.
3. Fire Resistance Duration of Structural Components
6mm single board: ≥ 2-hour fire resistance for partition walls
12mm double-sided board: ≥ 4-hour fire resistance for partition walls
Fire door cores & fire ducts: 1–3 hours fire resistanceKey fire resistance indicators:
Integrity (E): No flame penetration on the unexposed side
Thermal insulation (I): Temperature rise on the unexposed side ≤ 140°C
Load-bearing capacity (R): No collapse or severe deformation
4. Superior Fire Safety Advantages
Toxic-smoke free: Releases no CO, HCN, formaldehyde or other harmful gases when burned
No molten drips: No ignitable falling substances to prevent fire spreading
Low smoke emission: Clear visibility in fire emergencies for safe evacuation
Moisture-resistant fireproofing: Fire performance remains stable in high-humidity environments without deliquescence or deformation
Long-term durability: Aging and corrosion will not weaken fire resistance
5. Typical Application Scenarios
Fire partition walls, firewall panels, fireproof ceiling boardsFire door cores, fire air ducts, cable wrapping protectionHospitals, schools, shopping malls, machine rooms, tunnels, purification workshopsSteel structure fire protection, lightweight fire insulation systems
6. Fire Performance Comparison with Conventional Boards
MGO Board: Class A1 non-combustible, 1–4 hours fire resistance, smoke & toxin free, no drips
Gypsum Board: Class B flame-retardant, ~30 minutes fire resistance, fragile at high temperatures
Calcium Silicate Board: Class A2 non-combustible, ~1 hour fire resistance, low structural strength
7. Purchasing Guidelines to Ensure Fire Performance
Verify official Class A1 fire test reports per GB 8624
Chloride ion content ≤ 8% (prevent deliquescence, ensure high-temperature stability)
Density: 1.2–1.8 g/cm³ (higher density = better fire insulation)
Medium/non-alkali fiberglass mesh (anti-corrosion under high temperature)
Summary
With Class A1 non-combustible rating, 1–4 hour fire resistance, zero toxic smoke and outstanding high-temperature stability, MGO boards are the optimal choice for building fireproofing, especially for public venues with strict fire safety requirements and high pedestrian flow.
