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Monday, March 9, 2015

Understanding NFPA 86 – Class A Electrically Heated Ovens

The National Fire Protection Association’s Bulletin 86 (NFPA 86) is the minimum standard, required by law, establishing fire safety standards, including standards for the safe operation of oven and furnace processes.  Understanding and complying with the NFPA 86 standard can minimize the risk of a catastrophic event at your plant and is the single most important thing an oven builder, buyer, and operator can do.  This standard is updated on a regular basis with the latest revisions happening in 2015.
There are four classes of ovens as defined by NFPA 86 – Class A, B, C, and D.  In this blog we will be focusing on Class A electrically heated ovens.

Class A: Electrically heated Class A ovens must have all the safety requirements for Class B as well as the additional items listed below:
  • Powdered Exhaust Fan – an exhaust fan of sufficient size is necessary to evacuate the required amount of fumes, smoke, etc., eliminating buildup of hazardous materials in the work area
  • Extra Airflow Safety Switch – should the exhaust fan fail, the second switch will shut down the heaters
  • Purge Timer – used prior to heating to remove any flammable vapors and/or gasses that may have entered the work area while the oven was idle.
  • Extra Kilowatts (if required) – because these ovens will be forcibly removing heat from the work area (via the required exhaust fan), more heaters may be needed to maintain process temperatures. If this issue is not considered in the design stage, the oven may have a poor response time or be unable to reach the operating temperature necessary to run the load.
  • Extra Backup Contactors (if extra kilowatts are added) – if the oven is designed with extra kilowatts, additional backup contactors are required to provide adequate safeguards ensuring the heaters shut off if the primary contactors fail.
  • Internal Pressure Relief – another extra that must be included in an electrically heated Class A oven is an internal pressure relief. If a buildup of fumes leads to an explosion, this required feature will ensure that the event has an avenue of “controlled” release.

Click here to view the safety controls specified for Class B ovens that are also required for Class A electrically heated ovens in addition to the above requirements.

This is a simple overview of NFPA 86 for Class A ovens. Please consult the full NFPA 86 standard for all specifications and additional details.

Contact a Precision Quincy representative today at (302) 602-8738 or for more information on NFPA 86 and how to become compliant. 

All Precision Quincy Ovens are of welded steel construction and quality components are used throughout. Each oven is wired and tested at maximum temperature prior to shipping. Ovens meet or exceed NFPA-86, NFPA-70, OSHA & UL requirements. 

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