How is total surge pressure calculated?

How is total surge pressure calculated?

• A. Surge pressure caused by an opening valve plus working pressure in the pipe line
• B. Water hammer plus static pressure in the pipe line
• C. Surge pressure caused by a closing valve plus working pressure in the pipeline
• D. Working water pressure in the pipeline plus static pressure

Answer: (C)

Surge pressure in a pipeline comes from the abrupt change in flow when a valve is closed quickly. The moving water has inertia, so it can’t stop instantly, creating a pressure spike known as water hammer. This dynamic pressure adds to whatever pressure the system was already carrying—the working pressure in the line. So the total surge pressure is the combination of the pressure rise from the valve closure (water hammer) and the existing working pressure in the pipeline. That’s why the correct option is the one that describes surge pressure as the sum of the pressure caused by closing the valve (the water hammer) and the working pressure in the pipeline. Opening a valve doesn’t produce this surge; static pressure alone isn’t sufficient because it lacks the dynamic component from the abrupt flow change. For example, if the line runs at 40 psi and the closing valve generates 25 psi of water hammer, the total surge pressure would be 65 psi.

Surge pressure in a pipeline comes from the abrupt change in flow when a valve is closed quickly. The moving water has inertia, so it can’t stop instantly, creating a pressure spike known as water hammer. This dynamic pressure adds to whatever pressure the system was already carrying—the working pressure in the line. So the total surge pressure is the combination of the pressure rise from the valve closure (water hammer) and the existing working pressure in the pipeline.

That’s why the correct option is the one that describes surge pressure as the sum of the pressure caused by closing the valve (the water hammer) and the working pressure in the pipeline. Opening a valve doesn’t produce this surge; static pressure alone isn’t sufficient because it lacks the dynamic component from the abrupt flow change. For example, if the line runs at 40 psi and the closing valve generates 25 psi of water hammer, the total surge pressure would be 65 psi.