PREVENT SYSTEM FREQUENCY RESPONSE INDUCED SHAFT VIBRATION Resonance pump shaft deflection PULSATION
A common occurrence is, for a natural "wave speed frequency" of one of the lengths of pipe in the system, to return a pressure wave to the pump at a a frequency which coincides with a frequency at which the pump shaft will deflect, bend, or vibrate in its bearings.
This slight shaft movement, changes the distance from the impellers to the housing, and pressure fluctuation results. This is fed by the returning waves before long the pump & pipe system is suffering from heavy pulsation. The solution is to decouple the pump from the pipe "acoustically" with a PULSEGUARD Ltd. "WAVEGUARD", a no moving parts pulsation damper.
LIQUID DYNAMICS International Ltd. offer analytical and modeling services to predict these and similar problems, but the cost f a WaveGuard is often less than the cost of diagnostics and analysis. Exitational frequencies from "pressure wave speed" of "liquid acoustics" not only depend on knowing the exact lengths of all the pipe system nodes, but also on the effective compressibility of the system. Effective takes account of pipe wall elasticity, as well as liquid compressibility with entrained gasses, all of which change with temperature. Therefore unless you have a an absolutely constant temperature and level of gas absorption and or entrainment, it is more effective to install a WaveGuard decoupler, than to make analytical acoustical models.
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