is polyurethane sealant flammable


Polyurethane Sealant: Understanding its Flammability and Safety Measures


Polyurethane sealant is a widely used product in various industries, including construction, automotive, and manufacturing. It is known for its excellent bonding properties and resistance to moisture, heat, and chemicals. However, one common concern among users is its flammability. In this article, we will delve into the topic of polyurethane sealant's flammability and discuss safety measures to prevent any potential hazards.

1. What makes polyurethane sealant flammable?

Polyurethane sealants contain certain chemical components that make them susceptible to catching fire. These components include solvents, accelerators, and stabilizers. The presence of these flammable substances poses a risk if exposed to heat, sparks, or open flames. It is essential to understand the potential risks associated with using these sealants and take appropriate safety measures to prevent accidents.

2. Understanding the flammability rating of polyurethane sealants:

Polyurethane sealants are assigned a flammability rating based on their ability to resist or propagate flames. The most common rating scale used is the ASTM E-84 or the Steiner tunnel test. This test determines a material's flame spread index (FSI) and smoke-developed index (SDI). Lower FSI and SDI values indicate a higher resistance to flames and smoke development, indicating a safer product.

3. Safety measures when working with polyurethane sealants:

a. Adequate ventilation: Ensure that the work area is properly ventilated to minimize the concentration of flammable vapors. This reduces the chance of ignition and dissipates any fumes that may be released.

b. Eliminate potential ignition sources: Keep any open flames, sparks, or potential ignition sources away from the working area. Additionally, avoid smoking or using any electrical equipment that can generate sparks.

c. Proper storage: Store polyurethane sealants in a cool, dry place, away from direct sunlight or sources of heat. Ensure that the containers are tightly sealed to prevent the escape of flammable vapors.

d. Personal protective equipment (PPE): When working with polyurethane sealants, wear appropriate PPE, including gloves, safety goggles, and a respirator if required. This protects you from direct contact with the sealant and any potential inhalation of harmful fumes.

e. Emergency preparedness: Have fire extinguishers readily available in case of any unforeseen accidents. Additionally, familiarize yourself with proper fire evacuation procedures and emergency exits.

4. Steps to take in case of fire or accidental ignition:

a. Stay calm: In case of fire, it is crucial to remain calm and act swiftly. Alert others nearby and evacuate the area as soon as possible.

b. Sound the alarm: If the fire is significant, activate the nearest fire alarm to inform others and alert the local fire department.

c. Fight the fire, if safe to do so: If the fire is small and manageable, use a suitable fire extinguisher to fight the flames. Aim at the base of the fire and follow the PASS technique (Pull, Aim, Squeeze, Sweep).

d. Evacuate if necessary: If the fire is spreading rapidly or becomes uncontrollable, do not risk your safety. Evacuate the area and call emergency services for assistance.

5. Regulatory standards and certifications:

Polyurethane sealants must comply with industry standards and go through rigorous testing to ensure their safety. Look for sealants that carry certifications such as UL (Underwriters Laboratories) or FM (Factory Mutual) to ensure they meet the necessary fire safety requirements. These certifications indicate that the sealant has undergone testing for flammability and is deemed safe for use in specific applications.


While polyurethane sealants possess excellent adhesive and protective properties, it is crucial to understand their flammability risks. By following safety measures, adhering to proper storage guidelines, and being prepared for emergencies, potential hazards can be minimized. Always prioritize safety, and use polyurethane sealants responsibly to ensure a secure and risk-free working environment.


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