Project profile: Hospital UPS systems meet residential noise codes

The hospital’s extreme proximity to an apartment complex requires the UPS system to meet the city’s residential noise code and seismic regulations.


Centinela generator set site location. Courtesy: Valley PSIProject name: Centinela hospital medical center
Project type: System overhaul
Engineering Firm: MTU Onsite Energy
Building type: Health care facilities
Location: Inglewood, CA
Timeline: 2012-2013

Project challenges

In 2012, the 369-bed Centinela Hospital Medical Center began an extensive upgrade program that included a power system replacement. The most challenging aspect of the project was the hospital's extreme proximity to an apartment complex. To meet the city's residential noise code, the generators had to operate while producing sound at levels quieter than a normal conversation, while also meeting California's notoriously stringent environmental and seismic regulations.

MTU Onsite Energy generator set being offloaded. Courtesy: Valley PSI Noise codes

Inglewood city's sound ordinance requires that generator sets meet 45 dBA within 50 ft of the nearest property line. A typical generator set emits up to 105 dBA, which is equivalent to the loudness of a gas-powered lawnmower at 3 ft.

The installed generator sets are contained in a rigid structure that allows the units to run smoothly with minimal vibration. This helped Centinela achieve noise reduction levels to the sound of a whisper, exceeding the requirements for a facility situated in a cluster of crowded buildings with three sides of the hospital enclosed and the opening side facing an apartment complex.

Centinela ACS Dropover enclosure being set in place over generator set. Courtesy: Valley PSIAnother layer of Inglewood's noise ordinance is its sound curfew, which lifts every morning at 6 a.m. The noise of the hospital's original generator sets required Centinela to balance a 6 a.m. generator set startup time with the hospital's surgery schedule to avoid interrupting the flow of electricity to the hospital's critical equipment. Because they couldn't start the generator sets until the sound curfew lifted due to the loudness, the start time was occasionally delayed. With the MTU Onsite Energy generator sets, Centinela can switch the units on before the hospital begins its daily activities and procedures.

Seismic codes

California is also infamous for its earthquakes. To ensure its patients are safe, Centinela is subject to California's rigorous seismic codes. These codes, known as IBC 2009, require that all electrical and mechanical equipment supplied to California hospitals can withstand a 3-axis earthquake simulation called the "shaker table test." The test violently shakes full-size generator sets to simulate the movements of a real-world earthquake in laboratory conditions to ensure the equipment is functional with all essential components intact following a seismic event.

Centinela ASCO Switchgear and ATSs. Courtesy: Valley PSIEmission standards

Centinela is located in the South Coast Air Quality Management District, an air pollution control agency that sets smog and water quality standards for the area. The district requires that the concentration of a diesel engine's particulate matter emissions not exceed 450 milligrams per cubic meter. To meet this requirement, a diesel particulate filter, the combination of a filter and a muffler, was installed on the rugged EPA Tier 4 Rule 1470 compliant MTU 16V 2000 engine.

The project also called for the installation of a new underground diesel tank with several leakage backups, tests and sensors to ensure the tank can't leak into the water table. 

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