Dice and ducts
LAS VEGAS - In Las Vegas, hotels and casinos live and die by providing comfort, convenience and entertainment for gamblers and guests. Unless improvement projects are completed without interrupting either, they can quickly jump from mere annoyance to unacceptable aggravation, which can cost money.
The Venetian, one of the most luxurious hotel and casino properties on the Las Vegas Strip, considered this during the planning phase of a recent project - remodeling a food court's kitchen-ventilation system. Faced with stringent code requirements, short project deadlines and the need for minimum intrusion on guest comfort, the project required a uniquely suited system.
An indirect pathThe renovation was to an existing retail space that included a food court, shops and lots of people. Since it was a retrofit to an existing building, rather than new construction, design elements and occupancy restraints did not allow a direct route from hood to roof.
System requirements included:
- 0-inch clearance to combustibles when penetrating floors, walls and roof.
- Minimal rise on horizontal runs.
- Integrally installed fire suppression system.
The indirect path included a number of twists and turns, including:
- Maintaining a minimum 12-inch clearance from the wall within an electrical room, so not to interfere with existing electrical systems.
- Running 20 feet horizontally, offset 45 degrees, running another 12 feet horizontally, offset 45 degrees again.
- Penetrating a wall into a storage space while maintaining a 12-inch minimum clearance.
- Penetrating the roof, then horizontally penetrating a partition to the fan.
Another consideration was keeping radiated heat to a minimum, as the system ran through finished parts of the structure. The complexity of the system, combined with adherence to code, demanded a lot from the mechanical contractor and the system he was to install.
"The routing was the biggest problem. There were certain areas we could not go through, and the spaces we did were dedicated to other uses. So we needed to be as (non)intrusive as possible," said Brian Foster, mechanical contractor at Las Vegas' Performance Mechanical.
The hospitality industry is a finicky one, for good reason. A misplaced napkin, an empty glass or an unpleasant odor can have lasting impact on valued guests. At the Venetian, every effort was made to meet or exceed code requirements while paying the same attention to detail as is expected in other areas of the facility.
A traditional welded-and-wrapped grease-duct system was not suited for this application.
"Welding in a space like this creates all kinds of problems from smoke and fumes to life-safety issues," said Foster. "In order for us to weld we would have had to disable smoke alarms in the immediate area and take extraordinary precautions because of that. Another issue was inspection. We would have had three inspections; one for the welded duct and one each for each layer of fire wrap."
The welding, life-safety precautions and inspections would have led to scheduling issues and added installation costs. Foster sought a better solution.
SolutionsThe solution was found in the G Series grease duct from Metal-Fab Inc. A factory-built, ceramic insulated, integrally chased grease duct, Metal-Fab G Series is the only system that meets the requirements of the city of Las Vegas and requires no welding, according to Metal-Fab officials.
"Not having to weld is a big plus," said Foster.
"Traditional welded-and-wrapped black-iron systems will not allow for thermal expansion. Our system has specially designed adjustable lengths to allow for expansion in the event of a grease duct fire, to avoid warping and system failure," explained Jon Haney, an applications engineer at Metal-Fab. "Stainless steel is lighter and grease does not collect as easily on its surface. Also, we were going through spaces that would be accessed by people working on the electrical system and accessing storage spaces. With welded and wrapped, the wrap is always exposed to damage. If that occurs, the repair must be re-inserted. The Metal-Fab G Series outer casing protects insulation from accidental damage from someone working in the space."
Yet one of the most important factors was who was doing the work, not just in the type of system installed. Rather than multiple contractors for welding, installation, wrapping or installing a fire-rated chase, using Metal-Fab G Series grease duct afforded a better option.
"My biggest attraction was using a single source and ease of installation," said Bob Platt, project engineer at the Venetian. "A single contractor using a single product."
The system was designed at the Metal-Fab factory, with input from both Foster at Performance Mechanical, and Platt with the Venetian. The design specified 10-inch diameter 4G grease duct: incorporating a Type No. 304 stainless steel flue, 4 inches of high-temperature ceramic insulation, all enclosed within an aluminum-steel integral chase to protect the insulation. When installed, the system is approved by Underwriters Laboratories for zero clearance to combustibles, and affords significant protection to insulation and flue from potential future damage.
After drawings and the parts list were completed, components were manufactured under closely controlled factory conditions, then match-marked and shipped to a staging area at the Venetian. All that was left to do was assemble the components, apply caulk and closure bands for liquid-tight connections, then inspect the system.
(This article was supplied by Metal-Fab.)