In its first year of operation, Washington State Ferries transported four million passengers; today, the 25-vessel fleet makes more than 400 trips a day for more than 23 million passengers and 10.2 million vehicles annually. It is the largest ferry system in the United States. Fares range from no charge to $306.50, and crossing times vary from 10 minutes to three hours.

        For commuters and commercial users, riding the ferries is the shortest and most economical distance between two points, so getting to and from work is a breeze. For a growing number of tourists, the ferries provide an opportunity to island-hop throughout one of the most appealing environments in North America.

        Washington State Ferries’ two largest vessels, built in 1972, accommodate 2,000 passengers and 206 cars. Beneath the car decks, the engine room and control centers are supervised by the chief engineer, who oversees repairs and maintenance of the vessels’ mechanical and electrical equipment.

        A wide variety of air filtration products are installed within the vessels’ HVAC equipment for machinery cooling and indoor air quality for the crews’ quarters and passenger areas. Filter media types include paper, cloth, fiberglass, plastic, and electrostatic.

        Manufactured by Permatron Corporation of Franklin Park, Illinois, and sold by Baxter Air Engineering of Woodinville, Washington, the electrostatic air filters have been in use since 1981. According to Staff Chief Engineer Bert Bennett, " The Permatron filters are used in specific areas such as propulsion alternator intake air (to four 2mw General Electric air-cooled alternators), propulsion console cooling air supply, and panels that contain vital electronic equipment. They perform exceptionally well."

        Twenty-eight two-inch thick Permatron Model IN electrostatic air filters are used to protect the costly, sensitive machinery that keeps the vessels running smoothly. "By using the Permatron air filters," Bennett said, "we’re protecting valuable equipment.

        The Permatron filters are durable, industrial-grade products featuring rust-resistant, galvanized steel frames and woven electrostatic media. Electrostatic air filtration utilized a combination of impingement and air-charged particulate attraction. As airborne particles approach the charge field, they are drawn onto and through the media and held in the filter until it is cleaned. Model IN features Permatron’s Accumulator Chamber design which, the company says, supplies superior performance: maximum dust-holding capacity, minimal airflow resistance, and easy cleanability.

        On a monthly basis, and once the vessel is docked, crews remove the easily accessible, dirt-loaded Permatron air filters and replace these with a clean set as part of the operation’s regular maintenance schedule. Cleaning is simple: warm water and soap are used to backflush the filter media. Drain holes in the frames ensure thorough removal of captured particulate matter. Bennett says the crew considers the filters to be easy to clean.

        "If I had the crew to clean additional electrostatic filters, along with the storage space for the second sets, I would have them in my fleet’s heating systems, too," Bennett remarked.

        For Washington State Ferries, Permatron Electrostatic air filters have been the logical choice for application air cleaning and cost effective machinery cooling since 1981.