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of MVV gear pumps

The choice of the appropriate shaft seal is based on our extensive fluid knowledge and expertise. MVV provides a wide range of solutions, ranging from simple PTFE packing to more sophisticated options such as magnetic couplings or double mechanical seals. We also offer customized solutions and the ability to combine different seal types to meet specific requirements.

Gland Packing (PTFE – graphite)

The PTFE braid or rings are tightly wrapped around the driving shaft and compressed, then secured with a nut or screws, creating a highly dependable seal. This type of seal is widely recognized for its compatibility with high-pressure applications and its ease of maintenance, making it a cost-effective choice. Additionally, it can be equipped with a greaser or buffer fluid to enhance its functionality.

Gland packing

V-collar seal (PTFE – PE – carbon)

V-collars or chevron rings represent a modern advancement from traditional packing solutions. Operating on a similar principle, these collars are compressed and expanded by the gland follower. Their unique “V” shape allows them to expand and create multiple lip-seals. They are available in various compounds, typically PTFE+PE and PTFE with Carbon fiber, making them suitable for use with mildly abrasive fluids. Can be equipped with buffer fluid.

V- collar seal

Gland packing/v collar with fluid barrier PL2 (PTFE – glycerine)

This seal is an evolution of our standard packing. A fluid barrier is placed after the packing, preventing air from being sucked in from the shaft and acting as a real “barrier” for all fluids sensitive to humidity and oxygen. It is widely used for isocyanates and reactive chemicals. A transparent tube serves as a small reservoir and level indicator. A Corteco ring keeps the oil in place on the key side. It is successfully used with larger buffer fluid reservoirs on vacuum pumps. It is also available with V-Collars.

v collar with fluid barrier

Lip seal pa6 (PTFE – Bz – carbon)

A standard energized lip seal made of PTFE and carbon graphite compound is available. It can withstand temperatures over 200°C and is commonly used in hot-melt glue applications. It is held in place with a flange, which allows it to withstand pressures over 150 bar. This seal is simple, economical, and reliable and can works well at temperatures over 80-100°C.

lip seal

Labirynth seal

Known as “Viscoseal,” this is one of the most recent pump designs for handling melts and polymers. A spiral is grooved on the internal part of the hub, so the polymer is gently taken away from the high temperature. After cooling down (with the help of a gentle air blow), the polymer solidifies, creating the seal. It is practically maintenance-free and long-lasting, making it the most widely used in mono and multi-filament spinning and melt pumps. Often equipped with aluminum heat sinks.

Labirynth seal

Single mechanical seal

Mostly used in chemical applications, this seal is designed such that the rotating part is in contact with the atmosphere while the static part is immersed in the process fluid, creating a thin lubricating film between the seal faces. The materials most commonly used in MVV for this type of seal are 316 (or SiC)-Carbon-PTFE-FFKM.

MVV 600X400

Double mechanical seal

When absolutely no leakage is permitted, it is recommended to use a double mechanical seal. MVV typically employs a tandem configuration, which does not require pressurization of the barrier fluid. However, this configuration may not be appropriate for toxic, abrasive, or viscous fluids. An additional reservoir can be supplied with auxiliary equipment to manage the level of the barrier fluid.

Double mechanical seal

Magnetic coupling

The safest solution is certainly the magnetic coupling. One magnet is fixed on the pump shaft, and the other is fixed on the motor shaft. Both are separated by a thin containment shroud made of AISI316Ti or Hastelloy, which totally isolates the process fluid from the atmosphere. The excess heat is dissipated by the fluid itself, acting as a coolant, thanks to our Full-Flow system. However, this type of coupling is not recommended for abrasive, filled, or sticky fluids.

Magnetic Coupling

Sealing coupler

Used only for spinning pumps, it’s a precursor of the mechanical seal. The pressure built up in the gear chamber pushes the HSS coupler towards the hub flange creating a tight seal. The process polymer lubricates the whole hub.

Sealing coupler