Both surge and pulsation in a fluid processing system are the result of uncontrolled pressure waves caused by an abrupt change in fluid velocity. Fluid contained in an enclosed piping system has a physical volume and, therefore, its mass can be calculated. We can then determine acceleration forces needed to move that mass. Once in motion, the mass will stay in motion as long as enough force is applied to overcome friction loss plus any gravitational component. It can be said that hydraulic equilibrium is reached when the fluid is flowing in a laminar state.

Surge ("Water Hammer")

Since for all practical purposes liquids are not compressible, force or energy is not absorbed into the fluid but rather, it transfers through it. The kinetic energy of the moving fluid will exert all the force it has acquired to resist any condition that tries to cause a change in its velocity. Depending on the mass and velocity of the fluid and rate of change applied to it, highly destructive forces can be generated leading to catastrophic component or system failure.

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