Just what is a Class A oven? Often, its definition and function
are misunderstood. If you process combustible product at your facility, there
are certain requirements that your oven must meet.
Because a Class A oven is directly fuel-fired and made specifically for industries that process a combustible product or remove combustible vapors from a product in the oven, it is important to understand its definition and function. This is a brief synopsis of what they are; however, anyone who needs the complete requirements is best served by getting a copy of NFPA 86 Standard for Ovens and Furnaces, 1999 Edition, from the National Fire Protection Association (www.nfpa.org).
Class A ovens must have an explosion-relief area. The requirement for an explosion-relief area is that the interior cubic volume of the oven must have an explosion-relief area equal to at least one-fifteenth of the interior volume, or a 15:1 volume-to-venting-area ratio. For example, an oven with a total volume of 45 ft3 needs to have at least 3 ft2 of vent area.