Page 27: of Marine Technology Magazine (November 2012)

Titanium sensors, sapphire sensor windows, and wet-mate- able connections result in an instrument that will stand the test of time and reduce the total cost of ownership. Highly durable Xenoy polymer stands up to high pressures underwater with- out leaking and resists the corrosion of saltwater. Additionally, the materials perform reliably in higher temperatures, up to 80°C.XenoyMany of EXO?s polymer components are molded from Xe- noy resin. Xenoy was chosen because of its strength, impact resistance, chemical resistance, and low water absorption. YSI has been using the material for several years on  eld products with success. Xenoy is more environmentally friendly to mold than PVC and has better epoxy adhesion properties than acetal resin. ?We researched other undersea products and found that dive lights used Xenoy successfully. From this, we re ned an alloy mix for the polymer to especially suit the EXO instru- ments,? says Ron Metzger, Lead Mechanical Engineer on the YSI development team for EXO. The mix includes adding an- other alloy to the polymer for UV resistance and degradation. Metzger continues, ?Xenoy?s molding properties allowed us to  ll both thin and thick wall parts to create both an ergonom- ic shape for easier gripping as well as a unique, patent-pending reinforced interior structure.? The internal honeycomb-like structure of the EXO2 sonde imparts superior strength against external water pressures at depths of up to 250 m. The slim- mer EXO1 has an internal stainless steel sleeve overmolded in Xenoy polymer. Xenoy is used as the exterior surface in place of metal in high-pressure underwater applications without be- ing subject to corrosion like most metals. Titanium EXO sensors are made from grade 2 titanium, or commercial-ly pure titanium. Titanium is commonly used for deep-sea in- strumentation because of its corrosion resistance and strength at deep depths. EXO sensors are laser-welded shut and fully sealed, providing excellent leaking resistance. Metzger notes, ?These are great properties but titanium is an expensive mate- rial; however, the investment is worth it for the improved qual- ity and durability that oceanographic users require.? Connectors that Resist Corrosion EXO?s wet-mate connectors for sensors and cables resist Marine Technology Reporter 27www.seadiscovery.com MTR #9 (18-33).indd 27MTR #9 (18-33).indd 2712/3/2012 3:09:31 PM12/3/2012 3:09:31 PM