Grease duct air test parameters require a minimum positive air pressure of _____ water column for _____ minutes.

Grease duct air test parameters require a minimum positive air pressure of _____ water column for _____ minutes.

• A. 0.5, 10
• B. 1.0, 20
• C. 2.0, 20
• D. 0, 10

Answer: (B)

When verifying a grease duct, the goal is to prove the ductwork is airtight under a controlled positive pressure so any leaks would show up. The correct test uses a minimum positive pressure of 1 inch of water column and must be held for 20 minutes. This combination provides a reliable indication of airtightness: applying at least 1 in. w.c. ensures even small leaks create a measurable pressure drop, and holding it for 20 minutes gives enough time to detect those leaks rather than a brief transient reading. Using a lower pressure, like 0.5 in. w.c. for 10 minutes, could miss smaller leaks, while a higher pressure, such as 2.0 in. w.c. for 20 minutes, would impose unnecessary stress on the ductwork and isn’t required. Zero pressure wouldn’t test the duct at all. This testing approach helps ensure grease-laden air stays contained within the duct system and away from occupied spaces.

When verifying a grease duct, the goal is to prove the ductwork is airtight under a controlled positive pressure so any leaks would show up. The correct test uses a minimum positive pressure of 1 inch of water column and must be held for 20 minutes. This combination provides a reliable indication of airtightness: applying at least 1 in. w.c. ensures even small leaks create a measurable pressure drop, and holding it for 20 minutes gives enough time to detect those leaks rather than a brief transient reading. Using a lower pressure, like 0.5 in. w.c. for 10 minutes, could miss smaller leaks, while a higher pressure, such as 2.0 in. w.c. for 20 minutes, would impose unnecessary stress on the ductwork and isn’t required. Zero pressure wouldn’t test the duct at all. This testing approach helps ensure grease-laden air stays contained within the duct system and away from occupied spaces.