Understanding Fire Resistance Ratings in PUF and PIR Sandwich Panels
Fire Safety
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June 28, 2026
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4 min read
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By Sanjay Patil
A detailed look into fire safety certifications (B1/B2/PIR), smoke density test results, and structural integrity during fire events.
Industrial fire safety standards have become increasingly stringent. When selecting insulated sandwich panels, plant managers must differentiate between standard Polyurethane (PUF) and Polyisocyanurate (PIR) cores to satisfy insurance and safety norms.
PUF vs PIR: Fire Behavior Demystified
While both foams are thermoset polymers, PIR contains higher isocyanate ratios forming ring-like chemical structures that carbonize upon flame contact, creating a protective char layer that retards flame spread.