A Standard Review
In addition to ANSI Z50.1, NFPA 86, Standard for Ovens and Furnaces, also applies to bakery ovens in all respects. NFPA 86 makes reference to the sections of ANSI Z50.1, Bakery Equipment - Safety Requirements, that apply to bakery oven construction and safety.
Now that you are aware that bakery ovens are included in these standards, what must be done to prevent oven explosions and injuries?
According to Matthew Alessandroni of Reading Bakery Systems, Robesonia, PA, bakery oven explosions are rare. In fact, only one explosion has ever been reported to Reading Bakery Systems. "In the last 10 years, flame supervision and purge systems have practically eliminated explosions," said Alessandroni. Today's bakery oven problems seem to be most common in equipment that is more than 30 years old and has not been upgraded to current standards. According to Mike Wheeler of Advanced Design Concepts, Minneapolis, "Bakery ovens are grandfathered with equipment that is not necessarily safe. As experienced users retire, new employees may have to learn by example how to light the oven." This is where quality training comes in.
Operator TrainingLee Richardson of National Fire Protection Association (NFPA), Quincy, MA, believes it is vital that employees be trained in the equipment with which they are expected to work. NFPA 86 not only demands that operating, maintenance and supervisory personnel be thoroughly instructed and trained by a qualified person, but that they be required to demonstrate their understanding of the equipment and its operation.
Emergency response and shutdown training procedures also should be provided to employees. "Combination equipment supplier/bakery training incorporates equipment isolation and shutdown procedures with bakery emergency response procedures," explained Alessandroni. The belief that because these explosions are rare they will not happen to you does not qualify as an excuse for not training employees. "Thorough and repetitive operator and maintenance personnel training can drastically reduce the risk of explosion in ovens," Alessandroni said.
According to Wheeler, other than conducting the required inspections, oven users also should follow NFPA guidelines for purge times. NFPA demands that a means be provided to ensure adequate ventilation for the products of combustion on fuel-fired equipment. It also requires that prior to each system startup, provisions be made for the removal of all flammable vapors and gases that may have entered the heating chamber during shutdown. A timed preignition purge also must be provided. At least 4 scfm of fresh air or inert gas per cubic foot of heating chamber volume must be introduced during the purge cycle.
To further prevent an oven explosion from occurring and to ensure you are in compliance, Richardson suggests that those responsible for and those working with bakery ovens be certain that the equipment is designed in accordance with the requirements of NFPA 86. He also recommends that operators use the equipment only for what it was designed to do. "If the oven is designed according to the standard and properly operated by trained personnel in accordance with its intended use and design, the risk of explosion should be very low."