Sound and vibration studies have been conducted on cement mixing and pumping equipment to identify the loudest components so that the reliability and efficiency of noise and vibration reduction work can be improved.

During stages of the mixing process, the variable-speed centrifugal pump has minimal flow through it, yet it maintains high pressure. This pressure causes discharge cavitation that forms bubbles that collapse on the outside of the impeller. This cavitation is thought to be the main cause of noise and vibration from the pump.

The centrifugal pump supplying water for the cement-mixing process had sound pressures of up to 105 dBA ref 20μPa, power spectral densities (PSD) of up to 7.3 g2/Hz RMS, and can be heard over the unit's diesel engine noise. Hence, this location was selected as the best place to start noise/vibration reduction.

A standard centrifugal pump was tested and, in one test, was modified to have a smaller impeller and, in another test, sound attenuation blankets were installed on the pump. Sound and vibration measurements were completed on a test stand as well as on a cementing unit.

The testing with the modified impeller showed significant noise and vibration reduction. The sound pressure level was reduced approximately 13 to 16.5 dB when the impeller diameter was reduced from 12 in. to 11.25 in.; there was also a significant decrease in the overall vibration level of the unit. A corresponding loss of maximum pressure from 111 psi to 94 psi was observed but was not considered significant to the cement-mixing process. This pressure loss was overcome by increasing the speed of the pump, which caused a minimal increase in the noise and vibration signature. The sound pressure level was reduced 1.5 dB with the sound attenuating blankets installed.

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