What are Intumescent Coatings?
Intumescent layers are thin film coatings that Expand into an insulated carbon char when exposed to heat or flame. They help prevent the spread of fire and provide thermal insulation to protect the substrate. When heated to temperatures above 200°C, the coating kicks off an endothermic reaction that causes it to expand up to 10-50 times its original thickness. This expanded char acts as a thermal barrier and prevents flames and heat from damaging the underlying surfaces.
How do Intumescent Coatings Work?
Intumescent Coatings layers contain compounds that decompose when heated and cause the coating to swell up into a foam-like, low-density structure. The main components are:
– Acid Source: These compounds contain phosphoric or other polyacid groups that catalyze the reaction. Examples include ammonium polyphosphate.
– Carbon Source: Compounds like pentaerythritol or melamine provide carbon in their thermal decomposition to form the char.
– Spacer: Materials like clays or inorganic fillers maintain the coating thickness during expansion and prevent the melted components from re-liquefying at high temperatures.
When heat is applied, the acid source decomposes and creates an acidic environment. This causes the carbon source to char and the coating to expand dramatically into a low density, foam-like structure. The spacer component controls the expansion rate and helps maintain the integrity of the char layer. Together they form a thermally insulating char that protects the substrate from heat.
Applications of Intumescent layers
Some common applications of intumescent layers include:
– Structural Steel Protection: Used to fireproof steel beams, columns and other load bearing members. On exposure to fire, the expanded coating provides up to 4 hours of insulation protection as required by building codes.
– Cable and Pipe Coating: Protects cables, cable trays, conduits and pipes from fire. The expansion seals any openings to prevent flame spread through voids.
– HVAC Insulation: Acts as a thermal barrier on ducts, equipment casings and insulation facings to maintain integrity during fire situations.
– Marine/Offshore: Provides fire protection on ship decks, life rafts, cargo containers and offshore oil rig platforms as per SOLAS regulations.
– Architectural Components: Used on steel doors, windows, glazing systems, paneling etc. to achieve the required Fire Resistance Level ratings.
Testing and Certification of Intumescent layers
Extensive fire testing is done to certify intumescent layers for their intended use:
– Fire Resistance Tests (FRT): Evaluates load bearing capacity and insulation performance of coated structural elements as per standards like ASTM E119, UL 1709 etc.
– Surface Burning Characteristics (SBC): Measures flame spread and smoke development as per ASTM E84, CAN/ULC-S102, BS 476 Part 7 etc.
– Hose Stream Test: Checks integrity of char when exposed tocooling water spray for 10 minutes as per UL 1709.
– Independent Lab Listings: Products are approved and listed by certification bodies like UL, FM, Loss Prevention Certification Board etc. based on test results.
Proper application as per the listed thickness is critical to achieve the certified fire resistance rating. Coatings are also evaluated for abrasion/impact resistance, adhesion and compatibility with various substrate materials.
Benefits of Using Intumescent layers
Some key advantages of intumescent layers over other passive fire protection methods include:
– Thin Film Protection: Provides 1-3 hours of fire resistance with only 1-5mm total dry film thickness.
– Minimal Surface Preparation: Can be applied directly over previously coated or corrosion protected substrates with light abrasion.
– Durability: Retains flexibility and does not crack or delaminate with thermal cycling or building movements.
– Cost Effectiveness: Has lower overall cost compared to other methods due to simple application and minimal waste generation.
– Green Technology: Water-based formulations make them environment-friendly with low VOCs.
– Easy Maintenance: Minimal surface preparation required for overcoating to touch-up or extend the fire protection duration as needed.
In Summary, with stringent building codes and fire safety regulations worldwide, intumescent layers will continue playing a vital role in passive fire protection of structures and assets. Proper specification and certified product selection ensures they deliver reliable performance as intended in fire scenarios.
*Note:
1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it
