Saint-Gobain Seals Group’s OmniSeal® spring-energized metal-band seal has been qualified as a dynamic seal in micro fuel pumps for the aerospace industry. Micro pumps are designed to pump various types of fluids at high flow rates while requiring minimal housing space and operate by either electric motor or magnetic drive.
Applications for these miniscule pumps are found in aerospace, laboratory systems and fuel cells. Depending upon the size and pressure, they are able to pump from ten to hundreds of milliliters of fluids per minute and incorporate a variety of gear combinations based on speed requirement and fluid compatibility. The pumps range from an inch up to a few inches in length; most are less than an inch in diameter.
Many micro pumps use elastomeric seals; however, as operating conditions become extreme with low temperature, aggressive chemicals, high speed and minimal wear requirements, these seals fail prematurely. In order to solve these challenges, the Seals Group has developed a custom version of their OmniSeal® APS (Advanced Pitch Spring) seal (an extended heel design is shown here). The use of this seal has resulted in minimal seal and shaft wear as well as negligible leakage compared to traditionally used FKM U-cup type seals, surpassing the standard seal life requirement of 500 hours.
This custom APS seal is a very small shaft seal designed for dynamic sealing of motors at very high rpm and includes an aluminum metal band, a spring and a Fluoroloy® jacket. The polymeric Fluoroloy® jacket’s purpose is to seal against the shaft as well as the housing. The metal band prevents anti-rotation of the seal to ensure a static seal on the housing side, offering the additional advantage of providing effective housing sealing at low temperature. The spring offers a very light load and ensures leakage-proof sealing on the shaft side, where the shaft can be less than 1/8” in diameter.
In a typical operating environment, the shaft operates around 14,000 rpm which is equivalent to 458 ft/min (2.3 m/s) on a 1/8”shaft. The operating differential pressure ranges from 100 psi to 250 psi (689 kPa to 1,724 kPa) when sealing media such as jet propellant fluid and kerosene. In addition to the operating temperature ranging from -35°F to 185°F (-37°C to 85°C), the seal is required to be wear-resistant against a hard steel shaft. To withstand these conditions, a lubricated proprietary Fluoroloy® material with excellent wear characteristics and low coefficient of friction (CoF) is used.
Aside from the APS design, OmniSeal® spring-energized seals are available in multiple designs such as 103A, Spring Ring II, 400A, RP II and RACO™ 1100A and are also offered in various custom designs. These designs include seal jackets in various Fluoroloy® materials and springs in various configurations. The Seals Group’s sealing solutions have been used in a variety of applications such as the Delta IV heavy rocket with a reconnaissance satellite, the world’s first subsea gas compression station, harmonic scalpels, chemical analyzing equipment, and environmentally-friendly industrial dyeing process machines.
Please contact the Saint-Gobain Seals Group at [email protected] for assistance with unique applications or visit their website, www.seals.saint-gobain.com for more information on spring-energized seals and other sealing and polymer solutions.