huangyhg

foundation requirement for pumps
hi,
i am not a structural engineer but i have this issue on my lap where i need to give specs on foundation requirement(operation frequency due to vibration) for a pump skid. following is the working conditions.
the pump motor is operating at 60hz (460v 3ph). motor is 4 pole (1800rpm). gearbox reducer is currently operating at 385 rpm.
thanks

i assume you are talking about soill supported concrete pad. i have a paper that says that the mass of the concrete pad should be 2.5 times the mass of the equipment.
aci 350.4r says that foundation to equipment mass ratios can range from 2 to 5. i designed a slab to support a generator where the manufacturer wanted a ratio of 2 to 3. aci 350.4r also says that to ensure that critical equipment is not in resonance with the foundation, the natural frequency of the foundation should be calculated. to do this aci cites a reference, "design procedures for dynamically loaded equipment foundations" proceedings, asce, v.93, no, sm6, nov 1967, pp 169-193. i have never done this analysis, and typically use a mass ratio of 2.5. as the structural engineer i also make sure that the soil under the foundation is of granular material that is well compacted.
the main thing is that you don't want the equipment and the foundation to resonate.
also the width of the footing should be at least equal to the distance from underside of footing to pump c/l.
thanks guys

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