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Wednesday, April 1, 2015

Understanding NFPA 86: Class A Direct Gas-Fired 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 direct gas-fired ovens (Class A).


Direct Gas-Fired Ovens: All direct gas-fired ovens carry the Class A rating automatically because they introduce products of combustion into the oven work area. These volatile materials must be exhausted in a forcible manner. Direct gas-fired Class A ovens must include the following safety features:
  • 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
  • Manual Reset Excess Temperature Control – should the unit produce too much heat, the oven will trip and shut down the burner.
  • 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.
  • 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.
  • High-Low Gas Pressure Switch - should the sensor detect that gas flow is too high or too low, this switch will shut down the oven. Fairly even gas pressure must be supplied to prevent a buildup of combustible vapors.
  • Flame Safety/Spark Ignition – this control sends a high voltage signal to the spark plug for ignition, and the pilot gas valve opens to ignite the pilot flame. If no pilot flame is detected, the flame safety stops the attempt at ignition.


Click to view the safety controls specified for Class A and Class B electrically heated ovens. 


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 sales@pqovens.com 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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