Mechanische Dichtung Typ 21

Type 21 Style Mechanical Seals are general-purpose elastomer bellows seals designed for centrifugal pumps, rotary pumps and other industrial rotating equipment. They feature a flexible rubber bellows, a single-coil spring and a rotating seal face working against a stationary mating seat.

The compact design provides reliable sealing for suitable water-based fluids, lubricating liquids and general industrial pump applications. The elastomer bellows helps accommodate limited shaft movement, seal face wear and equipment tolerances while maintaining secondary sealing.

Type 21 style seals are widely used in industrial pump maintenance and aftermarket replacement applications.

Features & Advantages

• Compact Elastomer Bellows Design: Suitable for a wide range of general industrial pump applications.

• Single-Coil Spring: Provides axial closing force to maintain seal face contact.

• Automatic Wear Compensation: Flexible bellows construction accommodates gradual sealing face wear.

• Non-Pusher Construction: Reduces the need for a sliding secondary seal along the shaft.

• Multiple Face Materials: Carbon, ceramic, silicon carbide and tungsten carbide combinations are available for different operating fluids.

• Material Options: NBR, EPDM and FKM bellows materials can be selected according to fluid and temperature requirements.

• Replacement Compatibility: Various sizes and stationary seat designs can be sourced for existing pump installations.

Materials & Construction

Type 21 style mechanical seals typically consist of an elastomer bellows, rotating seal face, single-coil spring, drive components and stationary mating seat.

Carbon graphite is commonly used as a rotating sealing face material, while ceramic, silicon carbide or tungsten carbide may be used as mating surfaces.

NBR is commonly selected for oil-compatible applications, EPDM for suitable water-based fluids and FKM for selected elevated-temperature or chemical applications.

The final material combination should be selected according to the working medium, temperature, pressure and operating speed.

Typical Applications

• Centrifugal water pumps

• Industrial circulation pumps

• HVAC and cooling systems

• Water and wastewater treatment equipment

• General industrial process pumps

• Selected refrigeration and chiller equipment

• Pump repair and maintenance applications

Standard & Replacement Supply

CORA SEALS supplies Type 21 style mechanical seals in various sizes, elastomer compounds and sealing face combinations for pump manufacturers, maintenance contractors and industrial distributors.

Replacement seals can be sourced according to shaft diameter, spring assembly dimensions, stationary seat dimensions and existing samples.

For quotations, please provide the shaft diameter, complete seal dimensions, seat type, preferred materials and required quantity.

Pump model numbers, technical drawings or photos of the original seal can help verify dimensional compatibility before ordering.