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Pressure joints are sealed by media pressure, with a strong spring to keep seals together at startup or very low pressures. This classical technology requires a relatively large amount of torque and is suitable only for relatively media low pressures (<250 psi or 17 bar) |
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Plastomeric rotary unions use custom or commercially available “soft seals” made from application-specific polymers or elastomers. They are most suitable for applications with intermittent rotation and pressure. Though compact, these seals exhibit significant torque, heat generation, and wear rates. |
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Hydrostatic rotary unions deploy precise tolerances to provide no-contact sealing at high pressures, extending life and minimizing maintenance. The rotating element is suspended on a fluid film that circulates continuously at a very low flow rate. Fluid shearing limits the maximum speed of these unions to a few thousand RPM. |
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Mechanical seal rotary unions minimize seal wear, torque, and heat generation through intentional balancing of hydrodynamic forces. Flatness must be controlled within microns, and different seal materials are employed according to the desired RPM, pressure, and media. These unions perform reliably even at pressures >140 bar and speeds >40,000 RPM. Mechanical seal unions can be engineered to behave differently as the machine's operating condition changes. |
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