NFPA-99 Practice Exam

Which of the following fittings is not permitted for joining vacuum distribution pipeline systems?

1. Axially swaged

2. Memory metal

3. Non-removable push-fit

4. Welded

The correct answer is: Non-removable push-fit

In vacuum distribution pipeline systems, the integrity and reliability of joints are critical to maintain an effective vacuum system. The choice of fittings for joining these systems is governed by safety standards, including those outlined in NFPA-99, which emphasizes the avoidance of fittings that could compromise system performance. Non-removable push-fit fittings are not permitted because they cannot be easily disassembled or inspected. This lack of accessibility can lead to significant issues in maintenance situations, as these joints may become sources of leaks or other failures without any straightforward way to address such problems. In contrast, other fittings such as axially swaged, memory metal, and welded connections offer either mechanical advantages or robustness that allow for maintenance, testing, and, if necessary, repair, ensuring the reliability of the vacuum distribution system over time. Thus, non-removable push-fit fittings are not aligned with the safety and maintenance considerations central to NFPA-99 standards, making them unsuitable for use in vacuum distribution pipelines.