Effective September 2, 2015

Standard Information
Standard Number:
UL 710B
Standard Name:
Recirculating Systems
Standard Edition and Issue Date:
2nd Edition Dated September 2, 2011
Date of Revisions:
August 14, 2014
Date of Previous Revisions to Standard:
February 28, 2014
Effective Date of New/Revised Requirements

Effective Date (see Schedule below): September 2, 2015

Impact, Overview, Fees and Action Required

Impact Statement:  A review of all Listing Reports is necessary to determine which products comply with new/revised requirements and which products will require re-evaluation. NOTE:  Effective immediately, this revised standard will be exclusively used for evaluation of new products unless the Applicant requests in writing that current requirements be used along with their understanding that their listings will be withdrawn on Effective Date noted above, unless the product is found to comply with new/revised requirements.

Overview of Changes: These revisions to UL 710B are being issued to address changes in requirements for Interlocks, capture test (to align with current Practices and Procedures), simultaneous conduct of fire extinguisher tests, and new Requirements for Integral and non-integral recirculating downdraft systems. Specific details of new/revised requirements are found in table below.

Schedule:  So that shipping of products with Listing Marks will not be interrupted, an approximateschedule has been established to ensure Listing Reports are found compliant by Effective Date:

  • January 5, 2015 = 8 Month Report Review – Intertek will review all Reports. Update if compliance is verified or issue Findings Letter/Quote for any re-evaluations needed
  • March 2, 2015 = 6 Month Quote Cut-off – Quotes returned for necessary re-evaluations
  • August 3, 2015 = 30 Day Warning – Client advised of all non-compliant Reports to be Suspended
  • September 2, 2015 = Effective Date – ATM Suspended for all non-compliant Reports

Fees:  An initial review of Listing Report (s) will be covered by a direct billing project and will be invoiced at not more than $1200 per report.

Client Action Required:

Information – To assist our Engineer with review of your Listing Reports, please submit technical information in response to the new/revised paragraphs noted in the attached or explain why these new/revised requirements do not apply to your product (s).

Current Listings Not Active? – Please immediately identify any current Listing Reports or products that are no longer active and should be removed from our records. We will do this at no charge as long as Intertek is notified in writing prior to the review of your reports.

Description of New/Revised Technical Requirements

NOTE: Additions to existing requirements are underlined and deletions are shown lined out below.

ClauseVerdictComment Any component, combination of components, or assemblies required to comply with the requirements of this standard (including, but not limited to, Capture Test, Emissions Test, and Fire Testing), shall be interlocked such that the malfunction of any component or assembly shall result in rendering the recirculating and/or cooking appliance(s) inoperable.
58InfoCapture Test
58.1 (relocated unchanged from 58.3) During the cooking operation, the hood assembly is to completely capture all emission as determined by visual observation. The appliance is to be observed for the presence of visible smoke and grease laden air escaping from the hood assembly through the discharge port or through external seams, joints, penetrations, and that portion of the hood that captures grease laden vapors.
58.3 During the cooking operation, the hood assembly is to completely capture all emission as determined by visual observation. The appliance is to be observed for the presence of visible smoke and grease laden air escaping from the hood assembly through the discharge port or through external seams, joints, penetrations, and that portion of the hood that captures grease laden vapors.
For non-integral recirculating systems, the recirculating appliance hood is to be marked for use with the specific appliance(s) and product(s) as specified in 78.8 (a). The cooking surface temperature used during testing shall be the maximum temperature the cooking appliance is capable of producing, unless otherwise marked on the recirculating hood.
58.4 When necessary, the temperature measurements of the cooking surfaces are to be at a minimum of five locations on the top of the cooking surface to determine an average temperature. The thermocouples are to be securely held in thermal contact with the cooking surface and located as shown in Figure 58.1.

The test shall be conducted by loading the maximum amount of the food products noted below, on or in the cooking appliance and cooking the food product until it is overcooked (very well done). The cooking cycle is to be repeated at least once. 

  1. Deep fat fryers are to be tested with frozen, unbreaded fries intended for deep fat frying;
  2. Pressure deep fat fryers are to be tested with frozen, unbreaded chicken pieces;
  3. Griddles, broilers and similar appliances are to be tested withthawed ground beef patties made of 73 ±5 percent lean ground beef 4 ±0.25 inches in diameter and weighing 0.25 ±0.02 lb meat cakes (see Glossary 5.31). The beef patties are to be placed uniformly on the cooking surface. The quantity of patties placed on the cooking surface is to be the maximum permitted by the area of the cooking surface with a maximum of 1.0 inch between any row or the edge of the cooking surface. The patties are to be cooked on one side for 5 minutes, turned over, cooked on the other side for 5 minutes, and removed from the cooking surface;
  4. Ovens, roasters and similar appliances are to be tested using 2-1/2 to 3-1/2 lb skin-on and bone-in roasting chickens or quartered chicken pieces, loaded per the cooking appliancemanufacturer’s instructions;
  5. For testing ovens, as an alternate, when chicken does not produce visible cooking smoke and grease laden air, one sheet pan (nominal pan size 18 by 26 inches) filled with 1 lb of pork bacon and coated with one cup of sugar distributed evenly is permitted to be used. The pan shall be placed at the lowest location (rack) of the oven, and the oven run at the maximum temperature for 10 minutes; and
  6. Other appliances are to be tested using the food product(s) for which they are designed.

Exception: When one of the appliances specified in (a) – (d) is not intended for cooking the specified food (for example, donut fryers), the appliance is to be tested using the food product for which the appliance is designed.


Complete capture of smoke and grease laden vapor by visual observation shall be determined in accordance with the following considerations:

  • For tests using open griddle or broiler cooking appliances using beef patties, visual observation of smoke and grease laden vapors shall continue during flipping of the beef patties.
  • For tests using pressure fryers, ovens, or other cooking appliances with doors, visual observation of smoke and grease laden vapors shall continue during the opening of doors as part of the complete cooking cycle,
  • When removing food from the appliance, as required for the cooking operation, or at the end of the test, any residual steam, smoke, or grease laden vapors emitted from the food items are not to be considered for the purpose of this test.
61InfoFire Extinguishment Tests
61.1.7 The Automatic Operation Fire test, 61.3, and Delayed Operation Fire Test, 61.4 are permitted to be conducted simultaneously, when the extinguishing unit actuation (for test purposes) provides a visual or audible indication, but bypasses the actual activation of the extinguishing system. The extinguishing system unit is then to be manually actuated after a pre-burn of the time recorded between auto ignition and unit actuation, plus 30 seconds.

Supplement SA

SA1.1 These requirements cover electric commercial cooking appliances provided with integral or non-integral recirculating systems and downdraft systems, intended for installation in commercial establishments for the preparation of food.
SA1.2 These devices incorporate an air filtering system enclosed in a hooded or otherwise contained area intended to capture air from the cooking process area. The assembly typically includes a fan, downdraft ventilation assembly, or equivalent design and an air filtering system (consisting of a grease filter with or without other filtering means). In addition, the system includes a fire extinguishing system and a fire actuated damper.



Recirculating systems covered by these requirements are intended for installation in accordance with:

  • The Standard for Ventilation Control and Fire Protection of Commercial Cooking Operations, NFPA 96, and
  • The National Electrical Code, ANSI/NFPA 70.
SA1.4 These requirements supplement the applicable requirements in UL 710B. Glossary
SA2.1 RECIRCULATING DOWNDRAFT SYSTEM – Intended to remove smoke, grease-laden vapors, odors, and other impurities from the air by drawing the air away from the cooking appliance downward into a ventilation system. A downdraft ventilation system is compatible with an electric cooking appliance. This system consists of a fire extinguishing system unit, grease filters, interlocks, etc. all contained within a suitable enclosure.
SA2.2 COOKING APPLIANCE PERIPHERY – Consists of the Width and Depth of the appliance, excluding any accessories, mechanical parts, or extensions outside of the appliance such as tray slides, shelves, seated areas, overhangs or the equivalent.
SA3.1 Any surface located directly above the cooking appliance shall be of noncombustible or limited-combustible materials.
SA3.2 Limited-combustible materials are those found to have a potential heat value not exceeding 3500 Btu/lb (8141 kJ/kg), when tested in accordance with NFPA 259, Standard Test Method for Potential Heat of Building Materials, and includes either of the following: (1) materials having a structural base of noncombustible material, with a surfacing not exceeding a thickness of 1/8 in. (3.2 mm) that has a flame spread index not greater than 50; or (2) materials, in the form and thickness used, having neither a flame spread index greater than 25 nor evidence of continued progressive combustion, and of such composition that surfaces that would be exposed by cutting through the material on any plane would have neither a flame spread index greater than 25 nor evidence of continued progressive combustion, when tested in accordance with ASTM E 84, Standard Test Method of Surface Burning Characteristics of Building Materials; or ANSI/UL 723, Standard for Test of Surface Burning Characteristics of Building Materials.
SA3.3 Noncombustible Materials are substances that will not ignite and burn when subjected to a fire. One method of determining non-combustibility is compliance with ASTM E136, Standard Test Method for Behavior of Materials in a Vertical Tube Furnace at 750°C.
SA4.1 The recirculating, down draft appliance ventilation system shall be provided with interlocks such that the cooking fuel supply will not be activated unless the exhaust and supply air systems have been activated.
SA5InfoGrease Filters
SA5.1 For integral and non-integral recirculating systems, including downdraft appliances, the distance of travel from the appliance surface to the grease removal device shall not be less than the applicable installation specifications of NFPA 96, chapter on²Grease Removal Devices in Hoods”.
SA6InfoFire Extinguishing System Unit

The fire extinguishing system unit for recirculating, down draft appliance ventilation systems shall be in accordance with Section 37, and shall additionally comply with the following:

  • At least one fusible link or heat detector shall be installed within each exhaust duct,
  • A fusible link or heat detector shall be provided with each protected cooking appliance and shall be tested as part of the Fire Extinguishment Tests in SA8, and
  • A manual activation device shall be provided as part of each appliance.
SA6.2 Secondary filtration or air pollution control that is installed in the path of travel of exhaust products shall be provided with an automatic fire-extinguishing system, installed in accordance with the fire-extinguishing system unit manufacturer’s instructions, for the protection of the component sections of the equipment.
SA6.3 Filter media used in secondary filtration or air pollution control units and not complying with 42.4 “Grease Filters” shall have fire protection that is adequate for the filter media being used in accordance with the fire-extinguishing system unit manufacturer’s instructions.
SA7InfoCapture Test
SA7.1 Integral or non-integral recirculating, down draft systems system shall be capable of capturing and containing all the effluent discharging from the appliance(s) it is serving as determined by Section 58. The ventilation assembly is to completely capture all emission as determined by visual observation. The appliance is to be observed for the presence of visible smoke and grease laden air escaping from the cooking appliance periphery, by-passing the exhaust feature or emitting through external seams, joints, penetrations, or any portion of the assembly that captures or conveys grease laden vapors.
SA8InfoFire Extinguishment Tests
SA8.1 The fire extinguishment tests shall be performed in accordance with Section 61 and as described in SA8.2 - SA8.5.
SA8.2 The fire extinguishing system unit of a recirculating, down draft system is to be subjected to the Automatic operation fire test, 61.3, and Delayed operation fire test, 61.4 with each type of down draft cooking appliance necessary to determine compliance with these requirements for each type of down draft appliance intended to be used. Specific cooking appliance test methods are contained in 61.5 - 61.12. The cooking appliance shall be tested with the maximum specified distance between the cooking surface and the ventilation assembly.
SA8.3 During the fire extinguishment tests, all flames generated in the cooking area and any flames that occur in the filtering area are to be contained within the cooking appliance periphery. Containment shall include the openings in the grease-air stream enclosure provided for passage of extinguishing system unit piping or for passage of electrical conduit that are provided with fittings.
SA8.4 Prior to actuation of the fire extinguishing system unit, flaming shall not escape the cooking appliance periphery.

During fire extinguishment, when flaming escapes the cooking appliance periphery, the duration of the flaming shall not exceed 1 second.

Exception: The one second duration requirement does not apply to recirculating systems and downdraft appliances that comply with the provisions of Section 61.2.8, Exception a) and b).

SA9.1 The appliance shall be marked, “For installation in accordance with NFPA 96”.

CUSTOMERS PLEASE NOTE: This Table and column "Verdict" can be used in determining how your current or future production is or will be in compliance with new/revised requirements.

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