INTRODUCTION
Many of the largest and most unique buildings in the world are located on the Las Vegas Strip. The interiors of these facilities gives one the impression of being somewhere else and/or in a different time.

In Las Vegas, one can travel to Paris, New York, Venice, Egypt, or a tropical island, as well as another solar system, all within a few blocks. It is possible to take a trip back in time to the Wild West, the Roman Empire, or medieval Europe. Fantasy abounds, and to create these fantasies, the interiors of the facilities are transformed to achieve the desired illusion.

The interiors of these facilities contain artificial trees, large statues, handpainted canvas murals adhered to the walls and ceilings, as well as giant signs/LED screens, and numerous other types of themed faÁades. These themed interiors even include faux buildings inside the main facility.

How can the required fire protection aspects be incorporated into these themed facilities and still allow architectural freedom to achieve the design concept? What level of fire protection is reasonable?

This article focuses on the two previous questions to provide guidance in determining what level of protection is reasonable and offers some examples to demonstrate how that level of protection can be achieved. When determining a reasonable level of protection, the first aspect to consider is the hazard that must be mitigated.

CONSIDERATION OF THE POTENTIAL FIRE HAZARD
Looking at the subject from a performance-based viewpoint, the following aspects need to be considered.

• Proximity to fire sprinklers.
• Obstructions to sprinkler discharge.
• Flammability characteristics (ignition temperature, flame spread, heat release rate).
• Type of substrate and method of attachment.
• Physical properties of the decorative item (size, thickness, and product type).
• Properties of topical applications (pigments, varnishes).
• Combustible concealed voids ( compartmentation, sprinkler installation, and plenums).
• Fire-retardant applications.
• Applicability of recognized fire tests.
• Whether hazards are temporary or permanent.
• Proximity to, and significance of, ignition sources and adjacent fuel packages.
• Obstructions to occupant evacuation.

Bench-Scale Testing vs. Larger Scale
Factory Mutual Data Sheet 1-4 (Fire Tests) ¹ provides general information about fire testing. It indicates that smallscale "bench-type" testing should initially be conducted to determine if adverse-behavior of the specific material can be predicted under actual fire conditions.

This Data Sheet also indicates that small-scale testing may not be representative of the respective hazard. Failure to achieve ignition in small-scale tests is not substantial proof of noncombustibility. Large-scale testing may be necessary to determine the actual fire characteristics of a material. Data Sheet 1-4 states that "many materials incapable of achieving self-supporting fire in bench test configurations prove to be very combustible when subjected to largerscale testing."

Most fire testing references indicate that testing should be performed in accordance with the expected use of the material being tested. Potential ignition sources must also be considered.

UL 94 Vertical and Horizontal Burning, and NFPA 701 Large-and Small-Scale Versions
These types of tests are classic benchscale test methods that use a Bunsen burner type of ignition source. Except for UL 94 HB, the sample is typically vertical, and the burner is exposed to the lower portion of the sample. Visual observation of flame spread, char rate, and flaming droplets are evaluated. Typically, the burner exposes the sample for very short periods of time.

The results from these tests are only applicable to very small, transient exposure ignition conditions.

UL 1975
In the late 1980s, The Society of Plastics Industry, Inc., and Underwriters Laboratories (UL) developed testing criteria for foam plastics intended for use in exhibit booths, on film production stages, and for decorative objects. ² Decorative objects include such objects as mannequins, murals, and signs. The amount of exposed foam plastic is dependent on the proposed use and should be tested at the same thickness and density as the expected application. The size of the expected application should be limited to the size intended by the test. Larger applications should be tested in accordance with a larger-scale test.

Foam plastics in exhibit booths and film production are allowed to have a maximum heat-release rate of 100 kilowatts. Decorative objects are limited to 150 kilowatts. Due to the three-quarter pound (0.34 kg) wood crib used as an ignition source, with an approximate peak heat release rate of 18 kW, these tests may be considered small-scale.

The Steiner Tunnel Test
This test is known by several designations, including ASTM E-84, NFPA 255, and UL 723. As described in the NFPA Fire Protection Handbook, ³ this test was originally developed at Underwriters Laboratories in the 1920s, and the current physical design was completed in 1948.

This test was developed as a basis to compare the surface-burning characteristics of materials that form the exposed interior finishes of walls and ceilings in a building. Reinforced-cement board is used to establish the zero value, with red oak flooring being assigned a rating of 100. All other tested materials are compared with these two values. The peak heat release rate of the gas burners used as the ignition source is approximately 88 kW.

The flame-spread index is a numerical rating applied to tested materials. It is a calculated value based on the relationship between the distance the flame front extends within the test chamber and the respective time it took to reach that distance. A material with a Class A flame-spread rating has been tested with a flame-spread index of 25 or less.

Materials receiving a flame-spread index greater than 25 and up to 75 are assigned a Class B flame-spread rating. Class C materials have a flame-spread index greater than 75 and up to 200. For all classes, the smoke-developed index is limited to a maximum of 450.

One of the most important concepts to be aware of when using the Steiner Tunnel test method is that the burning characteristics of thin combustible materials can be affected by the properties of their substrate. The lid of the furnace constitutes the substrate for thin materials tested in the tunnel. This lid is a noncombustible refractory liner. As such, results obtained from this test method may be quite misleading when no substrate, or a combustible substrate, is expected for the proposed installation. In addition, the ASTM E-84 test standard specifies that the material be tested in the manner in which it is to be used.

Therefore, one often-misunderstood requirement is that this test standard expects a substrate to be included when thin combustible materials tested in this manner are installed within a building.

Since its inception, ASTM E-84 has been used to evaluate all interior finish materials. Over the years, it has been recognized that the results of the test method may not be indicative of real-life fire performance. For example, the NFPA 101 Handbook4 discusses tests conducted at the Fire Research Laboratory of the University of California at Berkeley and sponsored by the American Textile Manufacturers' Institute in late 1985. This testing demonstrated that flame-spread measurements alone might not reliably predict the fire behavior of textile wall and ceiling coverings.

Room-Corner Tests
Over the last 30 years, various roomcorner fire tests have been used and standardized. One example is the 30-lb (14 kg) wood crib room-corner test (UL-1715) used in many U.S. codes. Other examples include NFPA 265, which was developed specifically to address the flammability of textile wall coverings, and NFPA 286, which was developed to address interior wall and ceiling finish materials.

These NFPA tests were developed to provide additional engineering data such as heat release rate and smoke production as well as providing a visual observation of the extent of burning. These tests use a gas-fired burner placed in a corner of the room with a heat output that replicates the fire growth of the 30-lb (14 kg) wood crib exposure. The burner produces a 40 kW heat output for the first five minutes to simulate a small fuel package, such as a wastebasket. For the following 10 minutes of the 15-minute test, the heat output is increased to 150 kW (or 160 kW, depending on the test) to simulate a larger fuel package, such as a chair. One of the failure criteria is if flashover occurs. See the article in this issue on page 16 for additional information.

These tests provide a more appropriate evaluation with respect to material orientation, its actual installation, and a moderate fire exposure condition. For certain applications, newer versions of codes and standards allow this test as a substitute for ASTM E-84.

Other full-scale fire tests such as large open corner tests (FM 4880 or UL 1040) or nonstandard full-scale fire tests that replicate end-use conditions are also used to provide a more accurate measure of fire performance of wall and ceiling materials.

ORGANIZING THE APPROACH
There are many ways to organize fire protection approaches for unique interiors. One way is to break the features into similar concepts that are already addressed in codes and standards. This approach is outlined in Clark County's Guidelines for Unique Interiors. ⁵

These guidelines consider of the following unique interior design elements:

• Trim
• Wall Applications
• Ceiling Applications
• Artificial Plants and Statues
• Decorative Structures within Buildings