What does the Intermediate Scale Multi-story Apparatus (ISMA) test for?

The Intermediate Scale Multi-story Apparatus (ISMA) specifically tests for the fire resistance of curtain wall systems. This apparatus simulates the conditions that a curtain wall would experience in a multi-story building during a fire event, allowing for evaluation of how well these systems can withstand fire exposure and maintain their integrity, both in terms of preventing the passage of fire and protecting other building elements.

Fire resistance is critical for curtain walls as they often form the exterior skin of a building and may impact the overall safety of the structure during a fire. The ISMA’s design and methodology are intended to replicate realistic fire scenarios, providing valuable data on the performance of different materials and constructions used in curtain wall systems.

The other choices focus on different aspects of building safety and performance. For instance, wall strength under pressure addresses structural integrity; fire resistance between rated floors and non-rated walls pertains to how fire spreads within a space; and sound transmission involves acoustical performance, none of which are the primary focus of the ISMA test.