Maximum Surge Pressure for Water Formula |
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\( p_s \;=\; \dfrac{ p_w \cdot \Delta V }{ 2.31 \cdot g }\) (Maxium Surge Pressure for Water) \( p_w \;=\; \dfrac{ 2.31 \cdot p_s \cdot g }{ \Delta V }\) \( \Delta V \;=\; \dfrac{ 2.31 \cdot p_s \cdot g }{ p_w }\) \( g \;=\; \dfrac{ p_w \cdot \Delta V }{ 2.31 \cdot p_s }\) |
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| Units | English | Metric |
| \( p_s \) = Maxium Surge Pressure for Water | \(ft\) | - |
| \( p_w \) = Pressure Wave Velocity | \(lbf-ft\;/\;sec\) | - |
| \(\Delta V \) = Water Velocity Change | \(ft^3\;/\;sec\) | - |
| \( g \) = Gravitational Acceleration | \(ft \;/\; sec^2\) | - |
Maximum surge pressure for water is the peak pressure spike in a water filled piping system triggered by a sudden change in water flow, such as a rapid valve closure, pump shutdown, or abrupt obstruction. This occurs when the momentum of moving water is halted, converting its kinetic energy into a pressure wave that travels through the system at the speed of sound in water, though this varies with pipe material and wall thickness. The magnitude of the surge pressure is governed by the Joukowsky equation.
For instance, if water flowing in a steel pipe stops instantly, the surge could generate a pressure increase, assuming. Factors like pipe elasticity, air pockets, and system design influence the actual surge, and industry standards, typically limit surge pressures to the design pressure for chemical piping to prevent pipe rupture, joint failure, or damage to fittings.
