Page 50: of Maritime Reporter Magazine (October 2011)

50Maritime Reporter & Engineering News Midé Technology Corp., founded in 1989 by MIT PhD. Marthinus van Schoor, is a company created around the design and engineering ofsmart material based systems and solutions. His-torically, the company has not served any specific industry, in fact, it has served many of them, in- cluding: work on the international space station; energy harvesting systems on trains; underwater thermally controlled buoyancy systems; and, most recently, work with the U.S. Navy and the com- mercial marine industry. In 2004, Midé won a contract from the U.S. Navy to develop a novel bulkhead shaft seal using one of its smart materials, hydrogel embedded foam, a need born out of a situation where a worn out bulkhead seals nearly led to catastrophe. Typical bulkhead seals are based on a contact- ing design where a wearing material is always in contact with the spinning shaft, but Midé proposed to the Navy the use of a solution using hydrogel embedded foam for a non-contacting seal de-signed not to touch the shaft until a flooding event occurred. When the water hits the foam the foam expands and engages a seal with the shaft. The company dubbed these HydroActive seals, and the development ultimately led to Midé Marine. Midé?s first product for the Navy was a retrofit solution, the Reliant Series RM; a product was de- signed to integrate with housings already installed on a specific Navy class of ships. When the Navy contracted Midé to develop seals for a new vessel design, it wanted a standalone product sans the heavy housings. To fulfill this need, Midé devel- oped the Reliant YM (yoke model) bulkhead seal, which it has now supplied for two ships classes. In recent years, the company has developed and introduced a commercial grade seal called theOmni Series, which offers the same non-contact- ing HydroActive benefits as the Reliant Series for vessles with smaller shaft deflections than typical Navy ships require. This reduced shaft deflection requirement leads to a simpler design and a lower procurement cost.HOW IT WORKS Midé developed a robust and reliable hydrogel embedded foam that provides adequate force anddisplacement to engage a seal on the shaft. It is im- portant to note that it is scalable to most any size shaft. The process is completely reversible; the foam can be swelled and dried many times over. Heat above a certain threshold actually causes the gel to expel water. While the full process by which the company creates the foam is understandably proprietary, it is worthy to note a number of oper- ational benefits inherent in the design, installation and use of the seals, including: Almost zero maintenance costs due to non- contacting nature of the design;Safer seal as there is no opportunity for the seal to wear and fail Lenient mounting requirements again due to non-contacting/floating nature of the design;Unlimited shaft speed during normal opera- tion; still operable during flooding, but speed is limited to 25 m/s surface speed. Flexibility: Omni Series (commercial) seals range from 50 to 1000 mm, with a split design toease installation for refit or newbuild. Email: [email protected] FEATURE MARINE DESIGNBulkhead Shaft Sealing Really isRocket ScienceMedford, Mass.-based Midé Technology Corporation employs its ad- vanced brand of materials technology to keep navy and commercial vessels ship shape in the event of bulkhead shaft-seal flooding. ? By Greg Trauthwein Omni Series SpecificationsOperating Pressures.......................................up to 2 bar (30 psi) Shaft Surface Speed.......................................Dry = unlimited; Flooded ? up to 25 m/s (82 ft./s) Allowable Angular Misalignment.......................0.5 degrees Leak Rate when Activated...............................Less than 473 ml/min. (less than 1 pint/min.) Shaft Deflections............................................+/- 10 mm (+/- 0.39 in.) Key Features..................................................Non-Contacting Non-RotatingReusableLightweightApprovals.......................................................ABS MR Oct.11 # 7 (50-56):MR Template 10/5/2011 3:27 PM Page 50