The design allows the shutter curtain to plastically deform under blast pressure and progressively arresting the moving components of the curtain. These components are made up of elements that are connected to prevent them from becoming debris.
BLAST MITIGATING (PL1) PL1 (without bottom restraints) has been tested and shown to be capable of achieving limited damage in response to a blast load with peak pressure 75 kPA and peak impulse 1050 kPa-ms; and
BLAST RESISTANT (PL2) PL2 is fitted with a pair of automated bottom restraint device that will work with the motor operator to ensure that the restraints will always engage whenever the shutter is in the closed position. PL2 has been tested and shown to be capable of achieving limited damage and be fully retained in response to a blast load with a peak pressure 40 kPA and peak impulse 500 kPa-ms.
