Sello Mecanico Vs Sello Dinamico

Dynamic Seals

Dynamic sealing -- or hydrodynamic sealing -- is accomplished by a combination of pumping vanes on the rear shroud of the impeller and a secondary expeller located behind the impeller, which rotating with the shaft, impart a rotary movement on the liquid in the pump resulting in the liquid centrifugally moving away from the center shaft penetration in the case.

An equilibrium in the back of the pump is achieved between the pressure of the liquid in the pump and the atmosphere, creating an air void at the shaft penetration of the case while the pump is running.

The dynamic seal provides for zero leakage of the pumped product without the need for costly mechanical seals, packing, and lip seals or in most cases seal water and the associated supporting seal water systems. Product dilution due to seal water is further eliminated.

With no rubbing seal components to fail over time, the dynamic seal can operate reliably over the life of the hydraulic wet end of the pump.

Dynamic seals can offer reliable service in difficult applications that may include; varying amounts of solids, liquids that are close to saturation prone to crystallizing, scaling liquids and where operational upsets such as cavitation, dead heading of the pump and even dry running can occur.

Wilfley pioneered dynamic seals obtaining a US patent in 1920. All Wilfley pumps can be offered with Wilfley dynamic seals for difficult applications handling clear liquids and slurries with corrosive and erosive properties.

Dynamic Seal vs. Mechanical Seal

Dynamic Seal/Static Seal Mechanical Seal

Seal Mechanism Pump running: Primary seal is hydraulic.

Pump off: Static primary Pump running: Primary seal is two non-contacting seal faces separated by a thin liquid film.

Pump off: Static primary

Lubrication Requires none. External piping if seal wash is required. Requires cooling/lubrication. May require external sources, piping and hardware.

Pump hydraulics Vibration tolerant Vibration sensitive

Installation Expeller automatically set as impeller is adjusted. Multiple steps required for proper installation.

Seal Repair Field rebuild capability Seal must be returned to vendor.

Life Expectancy Pumpage determines seal life. Pump environmental conditions (cold, heat, dust or moisture) have little or no effect on seal life or performance. Pumpage determines seal life. Seal is sensitive to pump environmental conditions. Extra measures required to ensure adequate seal performance is achieved.

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