AIR SPRINGS SOLVE NOISE PROBLEMS
We are sorry to have let so much time pass since our previous “latest news” post.
We are happy to break the long drought to review the exceptional performance of our air spring systems and discuss one specific situation, out of a large and growing number of projects, where air springs were applied to solve a very challenging noise problem.
Edsel Palma with Mason West during the change out of steel spring mounts with our SLR-MAS-12000
Although steel springs can be designed for natural frequencies of 84 CPM (5” deflection) or less, and provide excellent isolation at lower operating speeds, high frequency hums and whines at 60 or 120 Hz., typical of all electrical, and many mechanical systems, can travel down through the steel spring coil with little reduction in energy. A rubber pad at the bottom of the spring mount can help, but it has been our experience on many occasions that no matter how many layers of rubber we have installed under the mounting (we have stacked layers of pad up to 6” tall) the high frequency disturbance found its way through.
Air springs eliminate the problem as the equipment is supported by a column of pressurized air within a flexible neoprene body capped and sealed at the top and bottom. We have not yet encountered a high frequency transmission problem that could not be solved with an air spring system, as the vibration and noise disturbance cannot travel through the neoprene body.
Mason type MAS air spring shown above. The air spring can be placed inside a housing, type SLR-MAS, shown on right, to resist potential seismic and wind loads
Air springs are often installed as a retrofit when the original isolation material did not do the job. The photos included with this article document one such project. In this situation, a very well-known tech company relocated to a building previously occupied by a large furniture business in downtown San Francisco. Of course, as luck would have it, a huge chiller was located directly above their future conference room and the sound and vibration that passed through the spring isolators resulted in very high noise levels below.
Since air springs always work, there is not much motivation to conduct follow up acoustical tests to measure the noise reduction. What makes this project unique, is the acoustician, Wilson Ihrig and Associates, completed the sound measurements after the installation and were nice enough to share the great results with us.
As shown in the graph shown below, the conference room had an initial sound rating of NC-65, which would be the typical noise level on a busy factory floor. The replacement of the steel spring mounts with Mason SLR-MAS supplied by longtime California agent, Mason West, reduced this to a very quiet NC-30, which you might encounter in a place of worship and more than adequate for the conference space.
We very much appreciate Jim Nelson and the team at Wilson Ihrig and Associates making us a part of the solution and sharing the rare follow up measurements. Thanks also to Edsel Palma of Mason West for working closely with the contractor to help carry the project to a successful conclusion.
Close up of steel spring mounts (supplied by others) supporting chiller
Mason Type SLR-MAS-12000 supporting chiller
Please contact us if you would like more information about our air springs or any of our isolation systems. We look forward to working with you.