For the residents of the brick and Formstone houses near CSX Transportation Inc.'s bulk terminal in Locust Point, it's a lot like living next to an airport. Three or four times each day, when the crews at the terminal crank up the big vacuum machines used to unload rail cars, the neighborhood reverberates with a roar like the sound of a jet plane preparing to take off.
Soon that piercing whine should be just an unpleasant memory.
Yesterday CSX announced that it had begun fitting the vacuums with electronic mufflers developed by Noise Cancellation Technologies Inc. at its research facility in Linthicum.
The use of the mufflers at the CSX terminal -- known as a bulk intermodal distribution services terminal -- marks the the first time the electronic devices have been used in an industrial setting.
"We're trying to be good neighbors," John Scheeter, CSX's director of operations for the terminal.
One of the three vacuum machines at the Locust Point terminal has been equipped with the electronic muffling device. The other two will be fitted with the new mufflers as part of a plan to install about 20 of them at bulk terminals throughout the CSX rail network. It costs CSX $6,000 to $7,000 per vacuum to add the new electronic mufflers, Mr. Scheeter said.
The vacuum rail car unloader looks like a giant metal kitchen funnel riding on a chariot. The unloader is wheeled between a tank truck and a rail car filled with a dry bulk commodity such as plastic pellets. Using a rubber hose, the vacuum sucks out the pellets, which flow to the metal funnel positioned over the truck. When the funnel is full, a valve opens and the pellets tumble into the truck.
John Spera, CSX's regional equipment service manager, tried to explain all of that over the roar of one of the vacuum loaders equipped with a conventional muffler. The noise required him and his listener to move a couple of hundred feet away.
A few minutes later he started up the vacuum loader that had been refitted with the electronic muffler. With that machine running it was possible to conduct a conversation just a few feet from the machine.
The muffling system, he explained, consists of two parts, a passive muffler and an active one. The passive muffler is simply an enlarged part of the air-piping system lined with screening. It has the effect of lowering the pitch of the noise created by the air flow.
The active muffler is a black, square, metal box with hatches on the side that look like wok covers. Next to the black box is a microphone connected to a computer. The computer identifies the nature of the sound and then instructs an amplifier to emit an anti-noise -- an identical sound wave 180 degrees out of phase with the noise to be muffled. The result is that the two waves collide and cancel each other out.
The benefits for CSX go beyond noise reduction. A conventional muffler slows the passage of air through the pipe, creating a force called back pressure. The electronic muffler causes no back pressure. That means the vacuum works more efficiently than the same machine equipped with a conventional muffler.
Mr. Spera said the electronically muffled machine uses 20 percent to 25 percent less fuel and can unload a rail car about 15 percent faster.
Michael Parrella, president of Noise Cancellation Technologies, said the electronic mufflers at the Locust Point terminal mark the first use of the technology in a commercial product. For the first time, he said, "the technology has been reduced to product."
He said he expects CSX to order his company's mufflers eventually for all of the approximately 80 vacuum machines CSX operates. That would mean about $250,000 in business for his company.