Keeping a Closed-loop Washing System Closed

Cleaning oil distributor trucks has to be one of the toughest, most challenging equipment cleaning jobs in industrial maintenance. Many of these trucks are cleaned only a few times a year, so there is a significant accumulation of asphalt and oil. To remove it, state departments of transportation formerly used diesel fuel as their solvent of choice. EPA and OSHA guidelines now ban this practice, so road crews have switched to a variety of strong chemical cleaners. Today, one of the most frequently used oil removal solvents contains d-limonene, which is obtained commercially from citrus fruits.

Even using cleaners formulated with d-limonene, cleaning a truck manually can take up to 18 hours of scraping, spraying and rinsing – and then repeating the process.

An automated, closed-loop cleaning technology

Tempe, Ariz.-based EST Companies has a specially formulated Tar and Asphalt remover (which contains d-limonene) designed to remove Tar buildup from Distributor trucks. EST Companies (www.estcos.com) specializes in the sale, installation, service and maintenance of large scale wash technologies and corrosion control facilities. For an October 2016 job with the Nevada Department of Transportation, EST provided a closed-loop Automatic Paving Equipment Cleaning System (APECS) from Riveer Company (www.riveer.com, South Haven, Mich.) to improve the DOT’s truck cleaning process. APECS is a complete system including galvanized wash rack, recovery and pressure pumps, settling tank and spray wands. The heavy-duty galvanized steel, above-grade wash rack has specialized automatic solids removal conveyors, and features the APECS’ tri-wall, double-bank spray bars which effectively remove Tar from NDOT distributor trucks utilizing EST’s Tar and Asphalt removal chemical.

The “zero discharge” technology includes a diaphragm pump to recover discharged solvent, preventing it from leaching into the ground. EST’s Tar and Asphalt remover chemical is filtered and reused. Wash water and contaminants from tar distribution trucks are 100% contained to the wash pad and are recovered to the filtration system.

The APECS system is modular, so it can be disassembled and moved from location to location.

Using the APECS, the Nevada DOT reduced truck cleaning time from 18 hours to 8 hours. And, according to DOT representatives, the trucks are “cleaner than they’ve ever been.”

The modular APECS system allows the wash rack to be configured to any piece of equipment and transported to most any site where it is needed. But, the modular nature of the APECS poses a challenge in ensuring a proper seal when bolting the steel racks together. “Typical silicone or neoprene sealants and gasket materials are rendered ineffective by the solvents used,” said Colin Murch, of EST Companies. “Without a proper seal – one that can withstand very strong chemicals and the pressure caused by the weight of heavy equipment – the system is no longer truly a closed loop.”

In search of a solution, Murch recalled the name Viton™, a high-performance fluoroelastomer manufactured by The Chemours Company (Wilmington, Del.). Murch contacted Pelseal® Technologies LLC (Bensalem, Pa.), a company that specializes in the manufacture of Viton™-based coatings, sealants and caulks. Pelseal has a library of formulations ranging in viscosity from aerosol spray paint Viton™ to high viscosity Viton™ caulk.

“Viton™-based fluoroelastomer caulks and sealants provide excellent resistance against a variety of corrosive chemicals and liquids including sulfuric acid, hydrochloric acid, nitric acid, diesel fuel, jet fuel and crude oil,” said Bill Ross, Pelseal’s president. “And, they can withstand temperature extremes of -40 to +400 degrees Fahrenheit.”

The 18’ wide x 56’ long wash rack used by the Nevada DOT was constructed of eight 18’ x 7’ sections bolted together. Murch applied a bead of Pelseal 2531 caulk to the bolts and section seams. He found that the product provided an excellent seal that withstands the chemical solvents used in the washing process – as well the pressure applied by the heavy equipment and exposure to the oils and other liquids that were discharged.

“It took hours of research to find a sealant that was chemical resistant, weather resistant and flexible enough to meet our application. Viton™ is known for having these characteristics, and the Pelseal sealant performed just as we’d hoped.”

Pelseal manufactures the world's broadest line of high performance liquid fluoroelastomer coatings, adhesives, sealants and caulks, many of which are formulated from Viton™. For more information about Pelseal products, visit the Pelseal website at www.Pelseal.com – or call Bill Ross at 215/245-0581.

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