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Magnetic Fluid Sealed Rotary Vacuum Feedthroughs
MAGNASEAL rotary feedthroughs provide long life and maintenance-free operation in high vacuum systems and other critical process applications.
A wide range of standard products can be found in the Rigaku catalogues. They offer designs based on both inch and millimeter standards, and can also work with you to provide a complete custom-designed product. In many OEM applications, a custom design provides significant advantages in system performance and packaging.
Magnetic fluid (ferrofluid) fills a small annular gap between a rotating shaft and a stationary magnetic pole piece. The gap is part of a high-energy magnetic circuit which includes the shaft and pole piece. The very large magnetic flux in the gap exerts a force on the fluid, holding it in place against pressure difference from atmosphere to vacuum, yielding a dynamic rotary seal in which there is no solid friction. Therefore, very long operating lifetimes are achieved.
Because the magnetic fluid has very low vapor pressure, it remains permanently in place for the entire lifetime of the seal, and does not contaminate the system. Some applications have special requirements (high temperature, highly reactive gases) which can be satisfied by selection of the optimum fluid from our family of fluid materials.
These products include the precision bearings and housings which make them complete, well-characterized components, ready to be installed in systems. You can choose the most convenient mounting style for your system.
Rigaku's leadership in feedthrough technology is widely recognized. Editors Hoffman, Singh, and Thomas invited Rigaku to supply the chapter on Feedthroughs in their reference book, Handbook of Vacuum Science and Technology, published in 1997.
The Rigaku Magnaseal (And SuperSeal) Advantages:
- No magnetic field in the vacuum: The closed and balanced Magnaseal magnetic circuit produces less than 10 Gauss as compared to >180 Gauss for competitive product. This allows the feedthrough to be located close to magnetic field-sensitive processes without effect on process.
- High pressure capacity: 2.5 atmospheres minimum, producing very long life seals. The Magnaseal will continue to seal even if the bearings fail (100% eccentric condition)! The Magnaseal will tolerate high shaft side loads that will cause competitive units to fail.
- High strength shaft: Three times the torque-transmission capacity of competitive products. Very resistant to shaft breakage or to seal failure due to excessive torque or side loads.
- Seal stages in stator: Shaft diameter is not reduced by seal stages cut in shaft as in competitive product. The seal stages cut into the shaft in competitive product can reduce the effective shaft diameter .08”.
- Field rebuildable: The high energy magnetic circuit of the Rigaku Magnaseal does not discharge upon disassembly, allowing the seal to be field- rebuilt. Competitive units require recharging seal magnets after re-assembly and ferrofluid re-charging.
- High external magnetic field tolerance: The closed, balanced, high-energy magnetic circuit of the Rigaku Magnaseal will operate reliably in >500 Gauss external magnetic fields without seal degradation versus less than 100 Gauss for competitive product.
- More rugged construction: The compact size of the Rigaku Magnaseal Seal Element allows larger bearings to be installed than typical competitive products resulting in longer life for the end user.
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