Evolve Mechanical Solutions was engaged to assess the installation of an existing Class 1 restaurant and provide a comprehensive report on any significant deviations from NFPA 96 and the Vancouver Building by Law regulations.
The site survey revealed substantial deviations from these standards. The installation poses an immediate risk to the occupants of the restaurant and tenants above. The primary concerns stem from the installation of a kitchen exhaust fan in an emergency exit corridor without a fire-rated shaft. The grease duct is constructed of sheetmetal instead of 16-gauge welded black iron duct, which is the required material per NFPA 96-14. If a fire were to occur in the kitchen, the kitchen exhaust fan would remove the flames and smoke. However, the sheetmetal would melt, thereby flooding the emergency exit with smoke and flames as occupants attempt to evacuate the building.
The following photographs provide a detailed description of the key issues relating to non-compliance with NFPA-96-14 and VBBL regulations. Notations in italic blue are excerpts from NFPA-96-14:
1. This photograph depicts the hood and grease duct assembly. The grease duct is constructed of sheetmetal, a common material in HVAC systems. NFPA requires 16 gauge black iron welded liquidtight ductwork. This ensures that in the event of a fire, occupants have sufficient time to escape, and the grease duct/kitchen exhaust system can effectively remove flames and smoke without failure. Furthermore, the red stamp/sign on the hood indicates that the hood is clean, which is clearly not the case.
7.5.1.1 Ducts shall be constructed of and supported by carbon steel not less than… No. 16 MSG
2. This photograph provides a close-up of the access panel serving the grease duct. It is not constructed in accordance with NFPA regulations, as evident from the leakage of grease. This may allow grease to accumulate in the space, potentially serving as fuel for a fire.
7.4.3.2 Access panels shall have a gasket or sealant that is rated for 815.6ºC (1500ºF) and shall be greasetight.
3. Further, the screws penetrate the grease duct, which is prohibited.
7.4.3.3 Fasteners, such as bolts, weld studs, latches, or wing nuts, used to secure the access panels shall be carbon steel or stainless steel and shall not penetrate duct walls.
4. Clearances from the grease duct to the limited combustible ceiling above must be a minimum of 3 inches.
4.2.1 …ducts shall have a clearance of at least…. 3 in. to limited-combustible material….
5. This photograph depicts the kitchen exhaust fan installed in the emergency exit. The grease duct and kitchen exhaust fan are typically not permitted to pass through a fire wall. However, if they do, they must be enclosed in a rated shaft to maintain the exit’s rating.
7.1.1 Ducts shall not pass through fire walls.
6. The following two photographs illustrate the sheetmetal connecting to the grease duct. As mentioned in the executive summary, the issue is that the sheetmetal will melt away in a fire. At the same time, occupants may be using this exit corridor to escape the building, thereby placing themselves in danger. Furthermore, grease is dripping out of the duct, indicating a lack of a solid connection.
7.5.1.1 Ducts shall be constructed of and supported by carbon steel not less than… No. 16 MSG
7.5.2.1 All seams, joints… shall have a liquidtight continuous external weld.
7. In the event of a kitchen fire, the kitchen exhaust fan rapidly accelerates to full speed to expel flames and smoke from the restaurant. Consequently, NFPA-96 imposes strict clearances from the location where the exhaust termination can be. No windows may be within 10’-0” to the sides and 32’-6” above the kitchen exhaust termination point.
7.8.3 Wall Terminations. Wall terminations shall be arranged with or provided with the following properties:
(2) The closest point of any air intake or operable door or window above the plane of the exhaust termination shall be a minimum of 3 m (10 ft) in distance, plus 76 mm (3 in.) for each 1 degree from horizontal, the angle of degree being measured from the center of the exhaust termination to the center of the air intake or operable door or window, as indicated in Figure 7.8.3.
8. Additionally, there were several other deficiencies, including the absence of a kitchen exhaust louvre, makeup air unit, and so on. However, the primary focus of this site survey was to address the major life safety concerns.
As always please hire licensed and experienced trades/ Mechanical engineers to design and install your commercial kitchens/ restaurants
James Hicks P.Eng.
Evolve Mechanical Solutions
604.837.8594
#300-328 W. Hastings St.
Vancouver, V6B 1K6
#fire #HVAC #Fail