Which of the following statements about Teflon tape application to pneumatic fittings is correct?

• A. Three to four wraps against the male thread, leave no tape hanging
• B. Wrap on the female thread only
• C. Wrap around both male and female threads
• D. Wrap once only

Answer: (A)

Seal in pneumatic fittings is achieved by using PTFE tape on the male threads as the joint is tightened. Wrap the tape around the male thread in the direction you will tighten, with three to four starts, and smooth it so nothing bulges beyond the threads. This amount provides enough material to fill the gaps for a good seal without creating layering that can interfere with seating or shed debris into the line. Leave no tape hanging past the end of the threads, because exposed tape can tear off or get into the system and prevent a proper seal. Wrapping on the female thread or around both threads isn’t necessary for standard NPT-style pneumatic connections, and wrapping only once usually doesn’t provide a reliable seal.