Presentation on theme: "NFPA 96 and Building Code Requirements for Commercial Kitchen Hood Systems Presentation for the Sevier County Fire Code and Building Code Officials Presented."— Presentation transcript:
1NFPA 96 and Building Code Requirements for Commercial Kitchen Hood Systems Presentation for the Sevier County Fire Code and Building Code OfficialsPresented by Roger Griffith, PEGriffith Engineering, Jefferson City, TNApril 21, 2004
2Course Outline Problem Areas Code Changes General Requirements Hoods Exhaust DuctsFansFire Suppression SystemCode ChangesNFPA 96International Mechanical Code (IMC)
3GENERAL REQUIREMENTS Where are commercial hoods required? NFPA 96: “Cooking equipment used in processes producing smoke and grease-laden vapors shall be equipped with…NFPA 96 – A-1-1 “…intended to include residential cooking equipment where used for purposes other than residential family use…”SMC gives exceptions for domestic equipment installed in dwelling units and ovens do not heat food above 2120F.
4Clearances 18 inches to combustible material 3 inches to limited-combustible material0 inches to noncombustible material
5Exceptions When the hood is listed for lesser clearances If the combustible material is protected as follows:28 gage sheet metal spaced out 1 inch on noncombustible spacers – 9 inch clearance to combustible material22 gage sheet metal on 1 inch mineral wool bats or ceramic fiber blanket reinforced with wire mesh or equivalent spaced out 1 inch on noncombustible spacers – 3 inch clearance to combustible materialReduced clearance to limited-combustible materials to zero clearance where protected by noncombustible materials or materials listed for the purpose of reducing clearance, and acceptable to the AHJ.
10Duct ClearancesProtection methods for ducts to reduce clearances shall be applied to the combustible or limited-combustible construction, not to the duct itself.Exception: Field applied grease duct enclosures and factory-built grease duct enclosures
12Duct EnclosuresField applied grease duct enclosure: A listed system evaluated for reduced clearances and as an alternative to a duct with its fire-rated enclosure.Factory-built grease duct enclosure: A listed factory–built grease duct enclosure system evaluated for reduced clearances to combustibles and as an alternative to a duct with its fire-rated enclosure.
13EXHAUST HOODS Type 1: Hoods designed for grease exhaust applications Type 2: Hoods designed for heat and steam removal and other nongrease applications. (NFPA 96 does not cover)NFPA 96: 2-1, 1998 Edition
14Exhaust HoodsHoods shall be constructed of 18 gage steel or 20 gage stainless.All seams, joints, and penetrations of the hood enclosure that direct and capture grease-laden vapors and exhaust gases shall have a liquidtight continuous weld external weld.
16Exhaust HoodHoods must be sized and configured to provide for the capture and removal of grease-laden vapors.Size:Configuration:Backshelf/Proximity HoodsShort-Circuit HoodsFace Discharge Makeup HoodsExhaust Only Hoods w/Supply PlenumsNFPA 96: 2-2, 1998 Edition
17Short Circuit HoodsHood performance is principally dependent upon net exhaust.Net exhaust = Total exhaust – internal makeupLarge airflows are required – high first cost & operating cost.
23Fire Dampers at HoodsFire dampers are installed in supply air connections where they penetrate the hood.Fire dampers are not installed in exhaust ducts.Fire dampers are not required in supply plenums that are isolated from the continuously welded shell.
24Filters and Baffles They are required! They must be 18 inches from cooking surface. (Hoods above char-broilers must be 4 ft above the cooking surface).Filters must be installed at an angle of not less than 45 degreesFilters must be easily accessible and removable for cleaning.NFPA 96: Ch.3, 1998 Edition
25EXHAUST DUCTSDucts can not pass through fire walls or fire partitions.Ducts cannot have dips or traps.Clearances must be maintained.Ducts must be 16 gage steel or 18 gage stainless.Seams and joints shall have liquid tight external welds.
26Openings in Exhaust Ducts LocationAt changes of directionFor damper cleaning and inspectionAt both sides of inline fansConstructionOn horizontal ducts – 20”x20”; if size is not possible, provide openings large enough for cleaning every 12 feet.Access openings shall be of the same material and thickness as the duct.Access panels shall have a gasket or sealant that is rated for 15000F and shall be grease tight.Enclosure openings are required to reach access panels. They shall be protected by approved self-closing fire doors.NFPA 96: 4-3, 1998 Edition
27Exhaust Ducts – Exterior Fasteners cannot penetrate duct walls.Ducts must be painted or be constructed of stainless steel.
28Exhaust Ducts – Interior Enclosures must be provided for buildings more than one story, and when penetrating a rated floor /ceiling assembly.Enclosure shall be sealed around the duct at the bottom.Exception: Field applied or factory applied grease duct enclosures.NFPA 96: 4-7, 1998 Edition
29Clearances at Enclosures 18” to combustible construction6” to noncombustible or limited-combustible constructionClearances may be reduced with field applied or factory applied grease duct enclosures.Multiple ducts are not permitted in a single enclosure(SMC only requires 6” clearance)
30Rooftop TerminationsMaintain 10 feet clearance to adjacent buildings, property lines, and air intakes, or locate exhaust 3 feet above air intakes.Ductwork must extend 18 “ above roof.
31Fans Fans must be listed for commercial cooking equipment. Rooftop FansRooftop fans must be hinged.Exhaust outlet must be 40 inches above roof.Termination must have a grease trap.Safe access must be provided to the fan for inspection and cleaning
32Fans Wall Termination Fans Wall must be noncombustible Maintain a minimum of 10 feet clearance from outlet to adjacent buildings, property lines, grade level, combustible construction, electrical equipment, air intakes or operable windows.Air intakes or operable windows above exhaust shall be 10 feet plus 0.25 feet for each 1 degree from horizontal.
33AirflowAir flow has traditionally been 1500 ft/min minimum. This is changing with the newer codes.Air volumes should be of sufficient level to capture and remove grease-laden cooking vapors.Makeup air shall prevent negative pressures from exceeding 0.02” wc in the cooking area.
34Fire Suppression Systems Automatic fire extinguishing systems must be in accordance withNFPA 12 - CO2NFPA 13 – WetNFPA 17 – Dry ChemicalNFPA 17A – Wet Chemical
37Fire Suppression Systems Exhaust fans must continue to operate after the extinguishing system has been activated. Fans do not have to be started upon activation of the extinguishing system.Makeup air supplied internally to the hood must be shut off when fire suppression system activates.All sources of fuel and electric power that produce heat to all equipment requiring protection by that system shall automatically shut off upon activation of any extinguishing system.
38Fire Suppression Systems A means of manual activation must be provided in the path of egress. (SMC requires it to be from feet of hood.)An audible alarm or visible indicator shall be provided.If fire alarm system is installed in building, it shall be activated.If electric power is required to operate the fire suppression system, it shall have a backup power supply or all sources of fuel shall automatically shut off when the system is inoperable.Portable fire extinguishers
39Fire Suppression System Inspection and ServicingSystems are required to be inspected every 6 months by properly trained and qualified persons.All devices, actuators, detectors, and components shall be checked for proper operation.Fusible links and automatic sprinkler heads shall be replaced at least annually, or more frequently.If required, certificates of inspection and maintenance shall be forwarded to the AHJ.
40Cleaning and Inspection The entire system shall be inspected by properly trained and certified personnel.Quarterly – high volume operations (24 hour, charbroiling)Semi-annually – moderate volumeAnnually – low-volume (churches)During inspection if the system is found to be contaminated with grease, the entire system shall be cleaned by properly trained and certified personnel.
41Cleaning and Inspection Hoods, ducts, fans, etc. shall be cleaned as needed to prevent them from becoming heavily contaminated with grease.
43Revisions to NFPA 96 Minimum Air Velocity through a grease duct 1,500 ft/min (1998 edition)1,200 ft/min (2001 edition)500 ft/min (Errata to 2001 edition in January 2002-1,500 ft/min has been in the codes since the 1930s (may have come from velocity of air in coal-burning furnaces)-Number was reduced because of ASHRAE Research Project 1033-RPAdvantages of lower fan speeds:-lower grease accumulation, less duct cleaning-easier to retrofit-reduced noise-energy savings (less makeup air)
44NFPA 96 – 2001Protection shall be provided on the wall down to the floor or to noncombustible material.Horizontal duct support systems shall be designed for weight of duct plus 800 lbs. at any point.Penetrations to ducts and hoods shall be listed.
45NFPA 96 – 2001A minimum of 5 feet horizontal clearance from fan to combustible material.
46NFPA 2004 under reviewChapter 15, Down Draft Appliance Ventilation SystemsA new section requiring a 20” x 20” opening for personal entry for duct cleaningA requirement for factory-built duct enclosures and duct-wrapped grease duct systems to be listed in accordance with UL 2221, “Tests of Fire Resistive Duct Enclosure Assemblies.”
47International Mechanical Code Performance TestNet Exhaust2003 CodeCapture and Containment Test
48Capture and Containment Test Adjust and verify all exhaust and makeup airflows.Operate equipment at cooking conditionsVerify capture and containment with smoke puffersVerify pressurization, and adjust if necessaryBuilding positive to outdoors, kitchen negative to dining