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Can They Take the Heat? PUBLIC ACCESS

Fire Researchers Apply Old and New Tests To Assure That Materials Meet Safety Requirements.

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Mechanical Engineering 122(02), 62-65 (Feb 01, 2000) (4 pages) doi:10.1115/1.2000-FEB-4

This article describes that fire researchers apply old and new tests to assure that materials meet safety requirements. Baltimore-based Hughes Associates Inc., a fire research firm, uses standard tests and computer modeling, and, in some cases, will develop tests to ensure that new building products satisfy the safety requirements of existing building codes. Hughes Associates also facilitates contact between its client and the appropriate code-making organizations, whether local, state, federal in the case of governmental agencies, or internationally through its offices in Singapore and in Milan, Italy. The data derived from the small-scale tests are also used in flame spread computer modeling testing. These tests use a series of proprietary computer modeling programs to predict the behavior of the product’s flames—for example, how high the flames would reach, and how quickly they would spread. The development of amusement park attractions is driving fire testing to prove that these attractions meet the stringent public assembly provision in fire codes.

Because there is always the potential of fire in any type of structure, meeting building codes is a crucial hurdle that new materials or assemblies must pass. This is complicated by the fact that most fire codes were written before these newer materials were developed. The codes require that building materials, from paint to furniture, will burn so as to give people in a structure maximum time to escape, and to keep fires small and confined to aid the firefighters who extinguish the blaze.

Fire testing companies aid building product manufacturers by determining at what temperature products will burn, how fast and long they bum, and how much smoke they will generate when burning. One leading fire research firm, Baltimore-based Hughes Associates Inc., uses standard tests and computer modeling, and, in some cases, will develop tests to ensure that new building products satisfy the safety requirements of existing building codes.

In the United States, regional bodies develop the building codes that regulate building materials for fire safety. The three major regional boards are the Building Officials & Code Administrators International Inc. in Chicago, the International Conference of Building Officials in Whittier, Calif., and the Southern Building Code Congress International Inc., based in Birmingham, Ala. These bodies cover the northeastern and midwestern states, the western states, and the southern states, respectively. City councils use the BOCA, ICBO, and SBCCI codes as models, adapting them as they wish, and vote on adopting them for their jurisdictions.

“We consider the codes to be the absolute minimum requirement for a products fire performance, and offer our clients two options when they are introducing building products not covered in current building codes,” stated Jesse Beitel, a chemist and senior scientist at Hughes Associates.

Initially, Hughes Associates will review the existing fire safety codes that regulate the application of specific products, or entire assemblies that are incorporated into commercial or industrial buildings. The first option is for Hughes to test and evaluate their fire performance. “If the product meets current safety standards, we present it to the local building code jurisdiction to show that the product is equivalent to the performance needed in the building,” said Beitel.

The second option involves working with third-party laboratories, such as Underwriters Laboratory, Factory Mutual, or model building code evaluation services to have the new product listed or accepted by the appropriate agency, a more time-consuming procedure than the first option.

Hughes Associates also facilitates contact between its client and the appropriate code-making organizations, whether local, state, federal in the case of governmental agencies, or internationally through its offices in Singapore and in Milan, Italy. This is to ensure that the codes will be interpreted properly, or that revisions can be made to increase the code’s flexibility to encompass new material while maintaining the same degree of safety specified in the original code’s language.

Hughes Associates developed its approach to fire safety testing while supporting U.S. Navy research initiatives since 1980. “Our work for the Navy was very broad, encompassing ways to reduce the threat of fire on surface ships as well as on submarines,” recalled Beitel. These measures included testing passive fire protection systems to prevent the spread of fire, such as fire-retardant bedding and furnishings, and fire-resistant insulation mounted on bulkheads.

The fire testing company also militarized some active fire protection systems originally developed for commercial structures for Navy use. “For example, hotels install vents in their atriums to remove smoke through the ceiling in the event of a fire. This cannot be done easily with a fire on the lower levels of a multilevel ship, so we designed a combination of air handlers and pressurizers to remove smoke through uninhabited areas on-board,” Beitel said.

The fire researchers use three small-scale fire performance tests specified under the American Society for Testing Materials El354 protocol: cone calorimeter, flashpoint, and firepoint. Cone calorimeter testing is used for solid materials, such as insulation. It involves placing a small, horizontal product sample in a steel holder and exposing it to a coneshaped radiant heater. The researchers measure how long it takes the sample to ignite, how long it burns, and how much weight it loses as it burns.

The smoke generated by the burning sample is captured and ducted across a specialized, bidirectional pressure and thermal probe to measure its flow. “Because flame spread varies in different conditions—for example, if the building product is installed vertically or horizontally—we measure the heat release rate to obtain good information over a range of applications,” noted Beitel. Hughes Associates accomplishes this by using an oxygen analyzer to determine the concentration of oxygen in the smoke, which corresponds to the heat energy released by the burning product sample.

The flashpoint and firepoint tests are used to study liquid materials, such as glue or paint. A small sample is poured into a cup heated until the vapors of the sample reach their flashpoint, or ignite. Firepoint refers to the temperature at which the liquid sustains burning.

The data derived from the small-scale tests are also used in flamespread computer modeling testing. These tests use a series of proprietary computer modeling programs to predict the behavior of the product’s flames—for example, how high the flames would reach, and how quickly they would spread. “We always validate the flamespread modeling findings with full-scale product testing, but the modeling saves us the time and expense of burning full-scale each time,” noted Beitel.

The development of amusement park attractions is driving fire testing to prove that these attractions meet the stringent public assembly provision in fire codes.

Grahic Jump LocationThe development of amusement park attractions is driving fire testing to prove that these attractions meet the stringent public assembly provision in fire codes.

If the product being tested is too large for testing at Hughes’ Baltimore facility, the fire researchers will farm out the full-scale testing to a third-party laboratory. This was illustrated by the testing of the Fiberock brand fiber-reinforced gypsum panels being introduced commercially by United States Gypsum Co. in Chicago. Hughes Associates guided U.S. Gypsum in working with Underwriters Laboratories Inc. and SouthWest Research Institute in San Antonio, Texas, to test the new product.

U.S. Gypsum was founded in 1902 and is the world’s largest manufacturer of gypsum board, joint compounds, plasters, and related construction products. The company is best known for its Sheetrock Brand Gypsum Panels.

Gypsum board has paper facings that are bonded to the gypsum core. This bond is loosened if the board becomes wet, or overly humidified. U.S. Gypsum developed a method of dispersing cellulose fiber throughout gypsum panels, producing homogeneous, paperless panels at its Gypsum, Ohio, plant. Three products will be coming to market under the Fiberock brand name: sheathing panels, water-resistant panels, and predecorated panels, which, being paperless, eliminate the bonding problem.

These Fiberock panels have a higher density and are more durable than conventional gypsum board. In addition, the process of making Fiberock offers options for core treatment, surface coating, surface texturing, and the production of eight-foot-wide panels for manufactured housing that are not feasible with conventional paper-faced gypsum board.

Fire researchers at Hughes Associates conduct so-called room testing by igniting new materials or assemblies in an open corner and monitoring their combustion to determine how the product will burn when installed in a room.

Grahic Jump LocationFire researchers at Hughes Associates conduct so-called room testing by igniting new materials or assemblies in an open corner and monitoring their combustion to determine how the product will burn when installed in a room.

However, these new gypsum panels do not comply with existing building code noncombustibility requirements. “Although we carry a great deal of in-house fire testing expertise, it became apparent that we needed to go beyond this to expedite obtaining building code evaluation reports for equivalency of Fiberock to conventional gypsum board. In September 1998, we approached Hughes Associates, because of their reputation for expertise in fire testing and working with building code authorities,” said Phil Shaeffer, architectural systems manager, systems and codes, at U.S. Gypsum.

During small-scale testing, one-gram samples of these Fiberock panels were burned in a bomb calorimeter. This is a small, spherical steel container that resembles the cartoon version of a bomb. Fuel is applied to the sample before it is ignited, and an oxygen feed promotes combustion. Researchers monitor the heat released from the burning sample by measuring the temperature increase of the water in a bath containing the bomb. This reveals how many Btu are potentially released per pound of material exposed to a fire.

Extensive cone calorimeter testing was used to further determine the Btu heat release, and tunnel testing was used to determine the surface burning characteristics of the Fiberock panels. Tunnel testing involves mounting a specimen on the ceiling of a tunnel-like apparatus, and igniting one end of the sample. The progression of flame down the tunnel is monitored, as is the smoke that is generated.

Larger-scale tests further explored Fiberock’s fire performance equivalency. In the thermal barrier test, halfinch Fiberock panels demonstrated their ability to block the heat of burning foam plastic from reaching the interior spaces of a building for 15 minutes, as required by the building codes.

Even larger tests of walls using Fiberock panels were also conducted. The ASTM E119 Fire Resistance Test for Building Construction and Materials was used to test the panels for wall assembly fire resistance, as would be required to separate areas or to separate shafts from occupied areas within most buildings.

“In the Room Corner test, we built two Fiberock walls and a Fiberock ceiling into a corner, then ignited a wooden crib in that corner. We videotaped and measured the progress of the fire by thermocouples and other instrumentation,” said Rich Kaczkowski, manager of the systems evaluation laboratory at U.S. Gypsum’s research and technology center in Libertyville, 111.

The reports with the data generated by these tests were submitted to the three national building code evaluation services for review. “We are optimistic that they will grant equivalencies for the use of these Fiberock panels,” said Shaeffer.

As a result of its Navy experience, Hughes Associates tests the fire performance of its clients’ products beyond the “pass/fail” tests specified by building code requirements. Instead, the company simulates the actual application to obtain a more accurate assessment of the risks posed by using a material or assembly. “In some instances, a completely new nonstandard test may need to be devised,” said Philip J. DiNenno, company president. ‘‘It’s our role to advise our clients on the best approach to take to be successful—and then to manage that process.”

Nonstandard testing was the basis of Hughes Associates’ work with a new plastic pallet manufactured by GE Plastics in Pittsfield, Mass., part of General Electric Co. in Schenectady, N.Y.. These pallets are designed to replace wooden pallets in Grocery Manufacturers Association applications, largely in handling food and pharmaceutical products. “Thirty-five percent of the 1.9 billion commodity pallets sold in the United States each year are for GMA applications,” according to Bruce Torrey, a fire protection specialist and the manager of regulatory programs at GE Plastics. About 87 percent of all pallets are made of wood, 2 percent are metal, and 3.9 percent are plastic.

Plastic s share of the pie is kept small by the fire characteristics of the polyolefins and polypropylene used to make most plastic pallets. “These materials will melt into pools as they burn, making it harder to fight the fire,” explained Torrey. As a result, the building codes place expensive restrictions on users of plastic pallets, requiring warehouses to beef up fire protection, limiting the height plastic pallets can be stacked, and requiring a sizable clear space around plastic pallets. In addition, these more stringent requirements increase fire insurance rates.

GE Plastics saw an opportunity for pallets made of its Noryl MH (materials handling) and Xenoy resins in today’s automated material storage and transport applications. Pallets made of Noryl MH and Xenoy are more durable and impact resistant than wooden pallets, reducing the need for repair. The pallets made of Noryl MH and Xenoy can also hold 2,800-pound loads with only a half-inch of deflection. Just as importantly, when the plastic pallets burn, they do not pool, but char, retaining their structure to help confine the blaze for firefighters.

GE Plastics commissioned Hughes Associates to test the Noryl pallets in late 1997 to prove that warehouses could replace their wooden pallets without upgrading fire safety systems. After conducting cone calorimeter testing, Hughes Associates worked with Underwriters Laboratory to develop a nonstandard test, now the UL 2335 protocol for fire testing pallets. This involved burning six 12-foot-high stacks of idle pallets and burning eight pallets carrying various commodities.

Hughes Associates mounted three different sprinkler systems above the burning pallets to study how well the pallets controlled fire under different sprinkler densities: 0.11, 0.21, and 0.31 gallon per minute per square foot. A 25-foot-diameter hood captured combustion gases and measured oxygen consumption to determine the heat release rate of each fire.

Torrey agreed with Beitel on the value of using mathematical modeling when testing the pallets. “Another fire safety laboratory would require 200 pallets to be burned, a much more expensive proposition than doing as much research and development up front the way that Hughes Associates did. They only burned about half as many pallets.

In addition to possessing similar characteristics to wood, these GE Plastic pallets can carry a 2,800-pound load with a half-inch deflection.

Grahic Jump LocationIn addition to possessing similar characteristics to wood, these GE Plastic pallets can carry a 2,800-pound load with a half-inch deflection.

“Data has no intrinsic value; you have to know how to use it in real-world environments. Hughes Associates continues to lead the curve in mathematical model. They foretell the future by being part of it,” said Torrey.

The growth of amusement theme parks represents a growing market for fire safety testing. Hughes Associates opened its office in Orlando, Fla., in 1996 to be near some of the nation’s most sophisticated theme parks, including Universal Studios, Epcot Center, and Sea World. These parks try to outdo one another by presenting encompassing, multisensory attractions that transport patrons to another time and place.

“Because theme attractions fall under the ‘public assembly’ provisions of building codes, they are held to stricter fire safety standards than most other occupancy types,” said Hamid Bahadori, a professional engineer and director of code consulting services at Hughes Associates’ Orlando office. Bahadori added that the theme entertainment attraction has a life cycle of roughly seven to ten years; then it is usually torn down and replaced with a new attraction.

Thus, the amusement parks’ engineers must create dramatically realistic illusions on a continuing basis that meet building and fire safety codes often written before the entertainment technology even existed. “Canned solutions simply can’t apply across such a wide variety of one-of-a-kind, highly conceptual structures as house entertainment attractions,” explained Bahadori, providing opportunities for Hughes Associates to test materials used in creating robots, props, or set pieces.

As in its commercial fire safety testing projects, Hughes Associates uses a combination of physical testing and computer modeling to address fire safety issues of patron egress, smoke management, emergency lighting, fire detection, and suppression in amusement parks.

Copyright © 2000 by ASME
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