Arizona Plumbing Practice Exam

What is the capacity of a 1 1/4 inch diameter schedule 40 metallic natural gas pipe that is 60 feet long with a pressure of 2 psi, a pressure drop of 1.0 and specific gravity of 0.60?

1. 3000 cu ft per hr

2. 3660 cu ft per hr

3. 4660 cu ft per hr

4. 5660 cu ft per hr

The correct answer is: 4660 cu ft per hr

To determine the capacity of a 1 1/4 inch diameter Schedule 40 metallic natural gas pipe, we can use the gas flow formula that takes into account the pipe diameter, length, pressure, pressure drop, and specific gravity of the gas. In this instance, the diameter of the pipe, pressure drop, and specific gravity are crucial parameters that affect the flow rate. The diameter of the pipe is significant because it directly influences the cross-sectional area available for gas flow, with larger diameters allowing more gas to pass through. For a 1 1/4 inch pipe, which translates to approximately 1.66 inches in inner diameter for Schedule 40, the area can be calculated, supporting a higher flow capacity. The pressure of 2 psi and specific gravity of 0.60 indicate the type of gas being used and its density. A pressure drop of 1.0 before reaching the final delivery point also provides insight into how much the pressure will decrease as the gas travels through the pipe, ultimately affecting the flow rate. Using standard gas flow rate formulas and charts available for natural gas applications, engineers can find that the combination of these parameters results in a flow capacity of approximately 4660 cubic feet per hour. This