Formation of resonances in piping systems

From years of experience, RohrLEx knows that every hydraulic system has multiple natural frequencies - but this does not automatically lead to resonance issues. For a resonance problem to arise, these natural frequencies must first be actively excited. In simple terms, the system resonances must be "hit" by the excitation source.

However, the mere presence of a matching frequency is not enough to trigger significant pressure pulsations. Whether a resonance problem actually occurs depends on several key factors: system damping, the amplitude of the initial pressure pulsation - especially in transient events such as pump startup - and the precise location of the excitation source within the system. Understanding and controlling these interactions is crucial to ensuring the reliability and efficiency of hydraulic systems.

Ideally, the system damping is large enough such that a pressure wave introduced into the system from the source is completely dissipated on its way through the system and back. Even if the resonance is "hit", there will be no pressure pulsation problem then.

As a rule, however, the pressure pulsation is usually high enough so that the pressure wave is not completely dissipated. To put it simply, a sufficient amount of the pressure wave is still left after travelling through the piping system and returning back to the source. In the resonance case, the pressure pulsation problem takes its course and the amplitudes reach large values within a few cycles.

RohrLEx has created a flyer on the subject of resonances in the piping system in which he explains the cause-and-effect relationships.