Beware of the difference pbi is not pbi

While they may sound the same, they are two completely different fibers. PBI and PBO are acronyms for the fiber chemistry each represents: PBI is the trade name for Polybenzimidazole, while PBO is the trade name of Zylon® or Polybenzobisoxazole.

PBI is a fiber made by PBI Performance Products, Inc. in Rock Hill, SC.

PBO is a fiber made by Toyobo in Osaka, Japan.

Since its introduction in 1999, PBO-blended outer shells have remained stagnant, used by only a few manufacturers and adopted by only a handful of fire brigades worldwide. In contrast, PBI has become the preferred choice for fire departments seeking great thermal performance, durability, and comfort.

Here's why...

Thermal protection

The ability of a fabric to protect against flame is its resistance to melting, shrinking, and charring. Fibers with higher decomposition temperatures create fabrics with better break open resistance to heat and flame. The optimal mix of PBI and PBI LP outer shells offer the highest break open and flame protection available.

What does that mean for the firefighter

It means that when exposed to direct flame, PBI LPTM fabrics will provide far superior break-open protection, compared to PBO/ARAMID blends. The Dynamic Flame Test is used to demonstrate the time it takes for an outer shell fabric to break open under direct flame. PBI LPTM outer shell lasts over 43 seconds while PBO/ARAMIDS lasts only 4.

WE CAN'T TALK ABOUT PBO WITHOUT TALKING ABOUT THERMAL CONDUCTIVITY

Durability of the outer shell is usually measured via tear resistance. The tenacity of the fiber characterizes strength. Note that the durability of the fabric can be affected by UV light. UV light affects the performance of para-aramids and PBO fibers.

TENACITY – The higher the tenacity, the stronger the fiber. Since PBI is not a strong fiber, it’s blended with para-aramids to provide strength in the fabric. An independent study has concluded that PBO’s tensile properties decreased more rapidly than those of para-aramid fibers, when exposed to UV.*

TEAR RESISTANCE – the industry test commonly used is the trapazoidal tear which measures the pounds of force required to propagate a 1/3 in. tear in a fabric.

Most PBO-containing fabrics have been phased out due to minimal adoption. While some remain available, they are seldom chosen by fire gear manufacturers or fire departments due to performance concerns.