Pierangelo Castagna, managing director of Larius, with a "Mist-Less" spray paint unit offering fast and simple cleaning without dismantling, thanks to its patented "Mist-Clean" system, and O-rings of Viton® ETP-S.

Larius Solves Paint Spray Seal Problem with O-Rings of DuPont Performance Elastomers Viton® Extreme™ ETP-S Fluoroelastomer

Major industrial users of spray painting equipment are only too aware of the costly downtime incurred each time they stop production to change paint or clear blockages. And there can be other complications too. Aggressive solvents, like acetone, do an excellent job of cleaning out the spray nozzles, but can ruin the vital O-rings seals in the spray guns - resulting in frequent seal replacement.

Larius S.r.l of Lecco, Northern Italy, well known for the quality of its paint spraying equipment, has found a time and cost saving solution to this common problem by fitting O-rings of DuPont Performance Elastomers Viton® Extreme™ ETP-S fluoroelastomer to the spray nozzles of its patented "Mist-Less" spray guns, used primarily by manufacturers of fine furniture.

"At least 25 times superior"

"Originally, we fitted standard fluoroelastomer O-rings to seal the pressurized air in the spray gun. But they lasted for just one spray cycle until change of paint. That's a maximum of one to two hours only, requiring several seal replacements per day," says Pierangelo Castagna, managing director of Larius. "But O-rings of Viton® ETP-S made with Advanced Polymer Architecture offer a lifetime at least 25 times superior - that means a minimum of 25-30 painting cycles. Now we are talking a matter of days, not hours, between seal changes."

Close up of "Mist-Clean" paint spray gun cleaning device showing O-rings of Viton® ETP-S.

Nozzles of spray guns tend to plug in use if the paint is not of the best quality or is insufficiently filtered, making it impossible to obtain a smooth and even surface. To minimize downtime due to normal spray-nozzle cleaning, Larius developed and patented its "Mist-Clean" system, an accessory mounted on the nozzle ring of the "Mist-Less" spray gun in the place of the normal application head. The device eliminates the need to dismantle the spray-gun head and nozzle, making cleaning fast and simple.

Major challenge accomplished

The major challenge was containment of the pressurized air which drives the spray gun. While ordinary O-rings solved the sealing problem, they were quickly degraded by exposure to the aggressive cleaning solvents used. Having to change the O-rings frequently negated the auto-cleaning/non-dismantling advantage of the Mist-Clean system. So the search was on for a long lasting high performance fluoroelastomer.

After numerous tests with alternative NBR and standard FKM copolymers and terpolymers, Larius consulted O-ring manufacturer G.F.G. Seal S.r.l. who recommended a compound of DuPont Performance Elastomers Viton® Extreme™ ETP-S fluoroelastomer provided by Marconigomma SpA. (Both companies are participants in the Genuine Viton® Program in Europe.)

"The new O-rings of Viton® made with APA provide an excellent quality/price ratio while ensuring the ongoing and effective operation of the Larius Mist-Clean self-cleaning device. We are very happy with the result and now have homologated seals of Viton® ETP-S as standard seals on this spray equipment. In addition, we plan to introduce a new very high quality spray head incorporating the new O-rings," adds Pierangelo Castagna.