FPE Extra Issue 25, January 2018

Clearing up Confusion on Codes for Fire Curtains
More Applications Likely as Standards Continue to Evolve

By Steve Weyel, BILCO Company

In the past decade or so, fire protection engineers, construction teams and architects have seen smoke and fire protective curtains used more frequently in commercial settings. As technology advances, the potential for even more applications seems likely. While fire curtains have been used for more than a century, their use in more commercial and industrial environments is quickly expanding. At the same time, however, there has been confusion over which codes and standards from various regulatory agencies apply and where fire and smoke protective curtains can be used.

The Early Stages

Fire and smoke protective curtains were first used in London in the late 1600s. A fire at the Drury Lane Theater in London in 1672 prompted the owners to rebuild with two safety features: a large water tank perched on the roof to douse potential stage fires, and the world’s first known safety curtain — an iron curtain mounted in front of the stage to protect the audience from back-stage fires. 

Movie theaters in the United States started to install fire curtains later that century, but a curtain installed at the Iroquois Theatre in Chicago did not prevent the deadliest single-building fire in U.S. history, in 1903, as documented by the National Fire Protection Association (NFPA). During a performance of Mr. Blue Beard, a popular musical, 602 people died when a fire curtain failed to deploy after it became snagged on a light reflector that stuck out under the proscenium arch.

The fire started when sparks from a short circuit on an arc light ignited a muslin curtain. The lack of exit signs and emergency lighting, exit doors that opened inward, and locked exits contributed to the deadly conflagration. The curtain had not even been tested before the theater’s opening just a month earlier.

Codes and standards continued to evolve to prevent similar tragedies, and in the 1980s, engineers and architects in Europe found other applications for fire and smoke protective curtains in commercial settings. It took several decades, but curtains eventually became more commonplace in U.S. commercial buildings. Regulatory authorities have updated codes and standards regarding their use, which has led to confusion among fire protection engineers and construction officials as they try to stay abreast of the changes.

What’s a Curtain, and What Does It Do?

A fire and smoke protective curtain assembly is a flexible, heat-resistant fabric infused with a coating to limit air infiltration. Fire and smoke protective curtains are designed and tested to limit the movement of heat and smoke generated by a fire. They can help contain heat and smoke within a specific volume, or channel it in accordance with the design intent. Fire and smoke protective curtain assemblies can be used for specific applications or as part of an engineered smoke control system. These curtains create a nonstructural barrier between interior portions of a building.

Comprising a flexible fire-resistant fabric mounted into a head box, such a product can be installed above an opening, or above the opening within the ceiling. In the event of a fire, the curtain is actuated electrically and descends upon receiving a signal from a fire detection initiating device. Curtains are available in large sizes to accommodate virtually any opening and can be weighted to assist in deployment, as well as limit deflection caused by air movement.

While curtains are not replacements for fire door assemblies, they offer interior design flexibility and provide an additional layer of fire protection that can be concealed from view.

Codes and Standards

Test standards from Underwriters Laboratories that apply to smoke and fire protective curtains include UL 10D, UL 1784 and UL 864. UL 10D and UL 1784 were recently introduced in the United States. UL 10D, which evaluates fire protective curtain assemblies intended to provide supplemental, passive fire protection as part of an engineered fire protection system, was approved in 2014. UL 1784 tests for air leakage of door assemblies and other protectives. UL 864 addresses requirements for control units and accessories for fire alarm systems.

NFPA 80 regulates the installation and maintenance of assemblies and devices used to protect openings in walls, floors and ceilings against the spread of fire within or into buildings. The 2016 edition of NFPA 80 added a new definition for fire protective curtain assemblies: NFPA 80, Section 21.1.1, clarifies that the current generation of curtain assemblies is not to be confused with fabric fire safety curtains, which are specifically intended for protecting proscenium openings. Fabric fire safety curtain assemblies are part of the passive fire-resistive separation between the stage and the audience seating area. They are intended to provide at least 20 minutes of protection so audiences can evacuate safely. For recognition as proscenium opening protection, curtains must meet the requirements of the 2016 Edition of NFPA 80 Chapter 20, which deal specifically with fabric curtains.

Applications for Curtains

Compliant applications include draft curtains for escalators, stair openings and warehouse storage areas; smoke partitions, including opening protectives; elevator hoist-ways to limit smoke migration; non-egress opening protectives in corridors that require a 20-minute rating and smoke barriers; proscenium openings (provided the curtains also meet the requirements of Chapter 20 of 2016 NFPA 80); and service-counter fire doors where 20-minute opening protectives are allowed. A UL Task Group is also considering the inclusion of horizontal sliding applications, which would create even more opportunities to use curtains.

Code compliance, performance and esthetic characteristics; integration with an engineered smoke control system; and available options should be considered when evaluating the use of smoke and fire curtain assemblies in commercial buildings. Options include firefighters’ override, sizing, orientation, guide systems, fabric materials and siren/strobe light capabilities.

Fire and smoke protective curtains are not a substitute for code-required structural hourly rated partitions, barriers or opening protectives that have been tested for fire endurance and hose stream performance.

Steve Weyel is with the BILCO Company.

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