What is the maximum distance from clean out to clean out on a straight run of grease laden exhaust duct?

The correct answer is based on standard practices and regulations surrounding the installation and maintenance of grease-laden exhaust ducts. These ducts must have clean-out access to facilitate regular cleaning and maintenance, which is crucial in preventing grease buildup that can lead to fire hazards.

The maximum distance of 12 feet from one clean-out to the next is a guideline that ensures accessibility for maintenance without the need for extensive disassembly of the ductwork. This allows technicians to efficiently clean and inspect the interior of the duct system to remove grease and ensure proper operation. If the maximum distance were longer, it could lead to areas of the duct being neglected during maintenance, significantly increasing the risk of grease accumulation and subsequent fires.

This guideline reflects a balance between maintaining a practical duct layout while still adhering to safety standards, making it critical for anyone working in environments that handle grease-laden vapors to be aware of and follow these requirements.