Technical Standards and Safety Authority (TSSA) G3 Practice Exam

How is the longest equivalent length determined for systems operating over 2 psig?

1. Add 20% of the length of the run

2. Add equivalent length of fittings to the shortest run

3. Subtract 20% of the length of the run

4. Add equivalent length of fittings to the longest pipe run

The correct answer is: Add equivalent length of fittings to the longest pipe run

Determining the longest equivalent length for systems operating over 2 psig involves accounting for the pressure drop that occurs due to fittings and bends within the piping system. When using the longest pipe run as the baseline, it's essential to add the equivalent lengths of any fittings or components that affect the flow. This approach ensures that the total resistance to flow is accurately reflected, providing a more realistic understanding of the system's performance. By adding the equivalent lengths of fittings to the longest pipe run, you create a comprehensive assessment of the system that captures the total distance that the gas must effectively travel, including the impacts of turns, elbows, valves, and other elements that can hinder flow. This method is crucial for maintaining efficiency and ensuring that the system operates within safe pressure and flow parameters. Other options do not account for the pressure drop adequately, whether by neglecting to assess the impact of fittings on the longest pipe run or making adjustments that distort the actual dynamics of flow within the system. Thus, adding the equivalent lengths of fittings to the longest pipe run is a sound practice for accurate system design and analysis.