Vertical transmission of vibration and noise to a research laboratory from mechanical equipment room – analysis and mitigation case study

摘要

A newly occupied large public university research building received floor-vibrationcomplaints from a laboratory located above a mechanical equipment room. Researchers,who observed surface ripples in water glasses on lab shelves, investigated and foundinterference in floor-mounted specimen incubators. Structural vibration and lowfrequency noise can effect sensitive laboratory equipment, degrade experimental specimensand reduce staff efficiency and productivity. Investigatory observations and measurementswere undertaken during business hours to determine vibration and noise conditions anddevelop a plan of mitigation. Measurement results were compared to permissible 1/3 octaveVibration Criteria (VC), which had been used for building design, and prominent narrowband (discrete) frequencies were compared. Central plant equipment, including pumps andcompressors are on ground level. Chilled water pipes from remote campus chillers aresuspended in a crawl space below. Building air handlers, exhaust fans and boilers are in apenthouse equipment room and on roof. Structure borne vibration and airborne noisemay be transmitted to laboratory spaces via building columns and beams, in pipes andducts and through vertical duct and pipe shafts. Results are graphically shown on charts.Mitigation measures implemented by the facility management are enumerated withsubjectively determined results.