What is the first step in performing smoke testing on a sewer line?

• A. Plug the section of the line to be tested, usually between two manholes.
• B. Open the manhole and position blower air duct into line.
• C. Start blower and blow air into the manhole for 5 or 10 mins.
• D. Place smoke bomb into bucket, ignite and lower into pipe section.

Answer: (A)

Smoke testing works by isolating a definite section of sewer pipe so that the smoke can only escape through actual leaks in that segment. The first step is to plug the section to be tested, usually between two manholes, which creates that sealed test area. With the ends closed, smoke injected into the segment will reveal leaks as the visible smoke escapes through cracks or joints, helping you pinpoint problem spots. If you skip sealing first, the smoke would simply vent out the open ends and you wouldn’t get a clear indication of where leaks are. After sealing, you would proceed with introducing smoke and observing leaks, and the other steps—like setting up the blower, delivering smoke, and generating it with a smoke source—follow in the proper sequence.