Liquids can wreak havoc on electrical components. But thanks to a good coil form design, controlled molding conditions, and the use of the same material for the bobbin and outer shell, an encapsulated solenoid has been created that resists liquid penetration.

By using DuPont's (Wilmington, DE) Zytel HTN polyamide and thermoplastic encapsulation technology, Wabash Magnetics Control Products (Wabash, IN) has developed a cost-cutting solenoid coil that stands up in demanding environments.

Wabash supplies the encapsulated solenoid to South Bend Controls (South Bend, IN) for use in South Bend Control's inert isolation valves. These inert isolation valves are used in laboratory and industrial equipment and supplies. The valves control the flow of high-purity or aggressive fluids, including reagents, alcohol, sodium hypochlorite, formaldehyde and sodium hydroxide.

Thermoplastic encapsulation allows Wabash to produce solenoids at substantially lower cost than metal-encased solenoids previously used by South Bend Controls. Using a coil form also molded from Zytel HTN, Wabash winds and terminates the solenoid's magnet wire and then places the coil in a metal frame. This assembly is then over-molded, producing a fully encapsulated part in a single step. No secondary finishing is required. There is also no emission of volatile organic compounds.

"The high-performance polyamide provides excellent resistance to aggressive chemical and cleaning agents encountered in the valves's service environment," says Brad Callis, project engineer at Wabash Magnetics Control Products. "Zytel HTN also allows us to meet global electrical safety standards developed by Underwriters Laboratories and the International Electrotechnical Commission with minimal testing."

For more information on Zytel HTN resins, call 800-441-0575, visit www.dupont.com/enggpolymers or Reply 6.

For more information on solenoids, call 219-563-2191, visit www.wabashmagnetics.com or Reply 7.