The mission of the fire department is to prevent fires, confine fires, and save lives and property. Most fire departments perform this mission through fire suppression and fire prevention services. Strong communication between these groups is a vital aspect of the community fire protection plan. A case in point is the following fire incident in Atlantic City, New Jersey, that led to an aggressive fire inspection campaign to eliminate future fires.

On March 31, 1999, the Atlantic City (NJ) Fire Department (ACFD) was dispatched to a fire in the kitchen of the Tropicana Casino Hotel, located at Brighton Avenue and the Boardwalk. The fire was reported at 10:51 p.m. by an Atlantic City Police Department officer several blocks away on the boardwalk. The officer reported a fire on the fourth-floor roof of the Tropicana as the flames were shooting high into the air.

On arrival, the district battalion chief immediately ordered Ladder Company 3 to throw its aerial ladder to the fourth-floor roof and ordered Engine Company 6 to provide exterior fire attack line coverage to the roof fire. ACFD Engine Companies 2 and 4 and Ladder Company 2 were ordered to enter the Tropicana and proceed to the second floor Seaside kitchen to attack the interior fire.

The Tropicana Casino Hotel is a fully protected property with automatic sprinkler systems, an automatic fire alarm, and kitchen range-hood fire suppression systems. By the termination of the incident, the ACFD had used four 13/4-inch handlines from the fire department standpipes to bring the fire under control.

The fire investigation unit was summoned to the scene. Investigator Thomas Bell requested that FM-1, the fire official, come to the scene. The fire caused extensive damage to the kitchen, in excess of $350,000; the kitchen was closed for several week

The fire investigation revealed several fire code violations that allowed the fire to gain quick headway and bypass in-place safety systems.

The fire began in the Seaside kitchen in an unattended cooking wok full of vegetable oil. The oil heated to its ignition temperature, and flames spread vertically to the hood plenum and grease filters. The hotel had recently replaced the filters with non-Underwriters Laboratory (UL)-listed grease filters. They were listed for nongrease-laden cooking vapor application. The fire easily penetrated the filter and spread across the oil-laden interior plenum and proceeded up the exhaust duct to the roof two floors above. The fire moved so quickly that it didn’t provide sufficient heat to activate the fire suppression system’s fusible link initially. The fusible link was located just past the duct collar outlet on the opposite side of the plenum. The fire extended into the greasy duct and traveled up to the fan housing on the fourth-floor roof.

The fire suppression system finally operated when Engine Company 6 placed a hoseline in the roof fan, driving a burst of heat back down at the fusible link. When the heat released the fusible link, the system nozzle above the wok did not operate because it was heavily covered with oil and grease. Fire officers at the scene reported other problems to the fire investigators, including the fire’s extension on the exterior of the duct in the sound insulation wrapping.

The ductwork was wrapped in a fire resistant material (Therma-fibre) made by U.S. Gypsum. ASTM E-136 considers this insulation noncombustible; it is used as fire-stopping material for up to two-hour fire resistance ratings. Ducts are required to be located in fire-rated shafts when they penetrate floors of a building. The ducts are not required to be wrapped in the ceiling void space but often are for sound attenuation. In either case, the fire should not extend in this insulation around the duct, especially above the sprinkler protection in a noncombustible ceiling void space.

Further investigation revealed that the insulation, over time, had become grease laden from vapors escaping the hood in the kitchen and leakage in the ductwork itself.


The Fire Prevention Division (FPD) official ordered an examination of all range hood systems in the city’s 13 operating casino hotels to see if this was a unique or widespread fire problem. The investigation revealed many issues with the existing building and fire code requirements and resulted in a more directed approach to reduce future kitchen range hood fires.

The fire code requires that fire suppression systems be inspected and certified biannual and that kitchen hoods be cleaned as often as necessary on a schedule to be provided to the fire official. All hotels were compliant with these requirements, but intense inspection revealed many unknown and undetected problems:

  • Because casinos operate 24/7, hoods and ducts need to be shut down and cleaned on a frequent basis, at least once every two weeks.
  • Cleaning companies would clean ducts by hand from access openings or by inserting workers in the duct with a paint scraper to clean the duct. It is not uncommon for these duct systems to be manifolded to several kitchens; duct runs can extend hundreds of feet. Building codes do not consider kitchen ducts occupied space and are not rated for human live loads. Fire Prevention also identified the ducts as permit-required confined spaces under the Occupational Safety and Health Administration (OSHA) definition, in that they have limited ingress and egress with a flammability and health hazard.
  • The clean-out access panels required by the building code were inadequate for cleaning. The building code required clean-outs to be 12 inches 2 12 inches at 20-foot spacing and any change of direction in the duct. We found that these requirements often do not allow adequate cleaning access to remove grease buildup. We also found that duct doors were often undersized. At the Tropicana, one kitchen grease duct is 5 feet 2 5 feet for 22 stories. To clean this duct properly, a cleaner must descend 20 stories from the roof on a swing chair in a permit-required confined space.
  • Many clean-outs were obstructed by other obstacles such as structural steel, conduits, HVAC, and sprinkler mains. This renders them useless and leaves the ducts dirty in these areas.
  • Duct insulation and the building’s noncombustible ceiling spaces were becoming grease laden. This was attributed to insufficient fan capacity, duct leakage, improper cleaning techniques, poor ceiling access, and variable-volume HVAC systems in the plenum spaces constantly drawing air to the space.
  • In-line fan integrity was insufficient at the motor vibration collars and duct fan connections. The inline fan must meet the same liquid-tight weld requirements and 2,000°F temperature rating as the rest of the duct until it exits the building. We discovered that often HVAC vibration collars were being used between fan and duct connections to damper fan vibrations. These collars were UL approved but had deteriorated. Stainless-steel directional grease filters were being switched for lower-cost mesh filters. This problem resulted from the purchasing department’s seeking cost savings and not understanding the filter application and specification.
  • Solid fuel materials such as those used in mesquite grills and wood-burning ovens were depositing creosote in the noncombustible ceiling spaces, rendering them combustible.


As a result of this fire, the ACFD FPD now requires the complete shutdown of all kitchen systems for a complete inspection on an annual basis. These inspections may occur during the Division’s normal working hours or at other hours at the hotel operator’s expense. The FPD requires that the cook lines be shut down two hours prior to the inspection and the ductwork be cold to the touch. All gas and electric service must be locked out and tagged out prior to the inspection. All access doors must be open and access must be provided to all ceiling spaces for complete duct inspections. Dirty ducts must be recleaned and reinspected before the kitchen can operate.

Fire inspectors have the authority to shut down any system not meeting the cleanliness inspections until the system has been properly cleaned. The ACFD has conducted this program for five years now and has not had a cooking duct fire in any casino hotel since the 1999 Tropicana fire.


Through the course of our efforts, we have also made the duct-cleaning industry safer. Confined-space permits must now be filed before entering the ducts. Lockout and tag-out procedures must be followed. Many new cleanout locations have been added to ensure proper cleaning and inspection access. These annual inspections and periodic spot checks have led to safer kitchens in the city. The FPD was able to develop useful duct system diagrams for every major kitchen in the city. The program has been successful in reducing kitchen fires and improving safety in the hood-cleaning service industry. In a recent newspaper article, a major international hood-cleaning company that works for the private sector and government credited its business success partly to the Atlantic City FPD’s rigorous range-hood inspections.

  • Large kitchen systems need detailed duct inspections to ensure there is no hazardous grease accumulation
  • Duct space in large buildings may be OSHA permit-required confined spaces if accessed by humans for cleaning.
  • The duct access panels required by some building codes may not be adequate for cleaning large ducts.
  • Detailed system inspection is needed. It should cover grease filters, fire systems and shutoffs, fusible links, fire dampers, liquid-tight seals, motor vibration collars, and duct integrity.
  • Inspecting noncombustible plenum areas, the insulation system, and ceiling void spaces for buildup of grease-laden vapors is critical to building safety.