Maximum Surge Pressure Head Formula |
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\( h_m \;=\; \dfrac{ p_w \cdot \Delta V }{ g }\) (Maximum Surge Pressure Head) \( p_w \;=\; \dfrac{ h_s \cdot g }{ \Delta V }\) \( \Delta V \;=\; \dfrac{ h_s \cdot g }{ p_w }\) \( g \;=\; \dfrac{ p_w \cdot \Delta V }{ h_m }\) |
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| Units | English | Metric |
| \( h_m \) = Maximum Surge Pressure Head in Length of Fluid | \(lbf \;/\; in^2\) | \(Pa\) |
| \( p_w \) = Pressure Wave Velocity | \(lbf \;/\; in^2\) | \(Pa\) |
| \( \Delta V \) = Fluid Velocity Change | \(ft \;/\; sec\) | \(m \;/\; s\) |
| \( g \) = Gravitational Acceleration | \(ft \;/\; sec^2\) | \(m \;/\; s^2\) |
Maximum surge pressure head is the maximum additional pressure head that develops in a closed conduit flow system, such as a pipeline, above its normal operating pressure head. This can also be called water hammer or hydraulic transient, occurs due to a sudden change in the fluid's velocity. This rapid change in velocity, typically caused by events like the quick closure or opening of valves, the starting or stopping of pumps, or even the movement of air pockets within the fluid, results in the kinetic energy of the moving fluid being converted into pressure energy in the form of a pressure wave.
This wave propagates through the system at the speed of sound within the fluid and the pipe material, reflecting off boundaries and causing significant pressure fluctuations that can exceed the system's design limits. The maximum surge pressure head is used in the design and operation of fluid transport systems, as it dictates the maximum stress that the pipes and other components must be able to withstand to prevent damage or failure.
