Case Study
Coop Reduces Noise to be Good Neighbor

The distance between MKC’s (Mid Kansas Cooperative) 2.1-million-bushel slipform concrete elevator at the north end of Marquette, KS (785-546-2214) and the nearest residence to the in-town location is only about 150 feet.

That creates a potential for conflict with neighbors on a number of issues, most notably from noise from normal operations. And one of the noisiest aspects of grain elevator operation is aeration fans.

The potential for broadcasting noise over a large area was particularly a problem with concrete tanks equipped with 40- or 50-degree concrete hopper bottoms. These hoppers provide the advantage of fast and efficient emptying and eliminate any need for personnel to enter the tank, but as a result, the Airlanco centrifugal aeration fans must be mounted 25 feet up the side of the tank to deliver air to the grain mass.

“We understood the situation, and we wanted to be as good a neighbor as possible,” says Jon Brown, construction project manager for MKC. “So we reached out to AGI Airlanco at a local GEAPS chapter meeting to find a solution.”

Barrel Silencers

AGI Airlanco, Falls City, NE (800-500-9777), suggested the use of barrel silencers. These barrel-shaped devices, 52 inches long from inlet flange to outlet flange and 19 inches in diameter, similar in function to a silencer on a gun, are attached to the fans and reduce noise output in two ways:

• The silencers are installed in a vertical configuration, directing sound down to the ground rather than out horizontally into the neighborhood.
• To muffle the sound further, the silencers direct sound through two tubes filled with shredded denim, the same material used in blue jeans.

In testing at 10 feet from the outlet, Airlanco has found its silencers typically reduce noise by about 15-20 decibels (db), particularly eliminating most high-pitch noise.

The silencers at the Marquette elevator were installed around mid-February. MKC took sound measurements before and after installation. At a distance of 30 feet, sound levels were reduced from 97 db before installation to 68 db after.

According to decibel charts found online, 97 db is roughly the equivalent to the noise level of a motorcycle, while 68 db is the level of an automatic dishwasher.

Reprinted from GRAIN JOURNAL May/June 2019 Issue