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What is the minimum air change rate required for mechanical ventilation to avoid classification in adjacent areas of commercial garages?

  1. Two changes per hour

  2. Four changes per hour

  3. Six changes per hour

  4. Eight changes per hour

The correct answer is: Four changes per hour

The minimum air change rate required for mechanical ventilation in commercial garages is specified to be four changes per hour to effectively prevent the accumulation of flammable vapors and ensure a safe environment in adjacent areas. This rate is established based on safety standards and regulatory requirements that aim to reduce the risk of fire or explosion in spaces where vehicles and equipment operated by internal combustion engines are present. Maintaining at least four air changes per hour ensures that any potentially hazardous gases released into the garage are sufficiently diluted and ventilated, thereby protecting adjacent spaces from becoming classified as hazardous areas. This standard takes into account factors such as the volume of the garage, the types of vehicles present, and the nature of any fuels being utilized, all of which contribute to the potential for hazardous conditions that warrant this level of ventilation. In contrast, options like two, six, and eight changes per hour either fall below the required standard or exceed typical requirements for normal commercial garage operations. The four changes per hour represent an optimal compromise between safety and practicality in most commercial garage situations.