FBD Rubber Bellow Mechanical Seal

The FBD Rubber Bellow Mechanical Seal uses an elastomer bellow as part of the secondary sealing and compensation system. Compared with compact multi-spring designs, the single-spring arrangement gives the FBD a relatively open structure around the spring area, which helps reduce fouling and blockage in suitable pump duties.

The rotating ring is designed to retain useful floating movement while the bellow transmits torque and accommodates axial movement. For replacement projects, the shaft size should be checked together with the main radial and axial dimensions before production.

Key Features

• Single-spring rubber bellow mechanical seal.
• Elastomer bellow provides secondary sealing and axial compensation.
• Open single-spring structure helps reduce the risk of spring blockage.
• Suitable for a wide range of pump replacement and OEM applications.
• Available with multiple seal-face, elastomer, spring and metal material combinations.
• Can be selected for water, oil and other weakly corrosive fluid duties after material confirmation.
• Detailed size references support dimensional replacement matching.
• Qixing supports customized matching from dimensions, samples and equipment drawings.

Technical Specifications

Material Selection

The FBD can be configured with different face, seat, elastomer and metal materials. The correct combination depends on the actual fluid, temperature, pressure and speed, so the working conditions should be confirmed before production.

• Seal faces: SiC / TC / Carbon
• Stationary seats: Carbon / SiC / TC / Ceramic
• Elastomers: NBR / EPDM / Viton
• Springs: SS304 / SS316
• Metal parts: SS304 / SS316

Why the Single-Spring Structure Matters

A common selection reason for the FBD is its single-spring layout. Because the spring is not divided into multiple small coils around the shaft, the structure is less prone to collecting deposits in the spring area under suitable service conditions. The rotating assembly also retains axial movement for compensation, helping maintain face contact as the seal operates.

Application Guidance

The FBD Rubber Bellow Mechanical Seal is commonly used in pump applications handling water, oil and other weakly corrosive fluids. The material combination should be selected for the actual medium. For example, elastomer compatibility may be different for water, oil and chemical service even when the mechanical dimensions are identical.

For applications with solids, concentrated chemicals or operation near the upper temperature, pressure or speed limits, provide the complete duty conditions so the configuration can be reviewed before production.

How to Select the Correct FBD Seal

• Confirm the shaft diameter or existing FBD size.
• Check the radial dimensions of the rotating assembly and stationary seat.
• Check the axial installation length.
• Provide the actual working medium.
• Provide operating temperature, pressure and shaft speed.
• Confirm the required face, seat and elastomer materials.
• For replacement orders, send clear photos, an old sample or a dimensional drawing.

Replacement Matching

For replacement work, the model name alone is not sufficient. The shaft diameter, seal outside diameter, seat diameter and axial length should be compared with the existing seal or equipment drawing. This is especially important when several manufacturers use an FBD-style designation but publish slightly different dimensional conventions.

Why Choose Qixing

Qixing, the mechanical seal brand of Ningbo Yade Fluid Connector Co.,Ltd, manufactures and supplies mechanical seals for industrial buyers. For FBD projects, our factory can review size, materials and replacement dimensions based on operating data, samples and drawings.

When the original model marking is incomplete, providing the shaft size and key installation dimensions gives Qixing a clearer basis for matching before quotation and production.

Frequently Asked Questions

What type of seal is the FBD Rubber Bellow Mechanical Seal?

It is a single-spring elastomer bellow mechanical seal designed for pump and replacement applications.

Why does the FBD use a single spring?

The single-spring layout provides a relatively open spring structure and helps reduce the risk of spring blockage under suitable service conditions.

What is the operating temperature range?

The FBD can be configured for temperatures from -20°C to +200°C, depending on the selected materials.

What is the maximum operating pressure?

The maximum listed pressure is 2.7 MPa.

What is the maximum sliding speed?

The maximum listed sliding speed is 25 m/s.

What materials are available for the seal faces?

Available face options include SiC, tungsten carbide and carbon.

Which elastomers are available?

Common elastomer options include NBR, EPDM and Viton.

What fluids can the FBD seal handle?

Typical duties include water, oil and other weakly corrosive fluids. Final suitability depends on the selected materials and the actual operating conditions.

What information should I provide for a replacement quote?

Provide the shaft size, key dimensions, working medium, temperature, pressure, speed and any old-seal photos, samples or drawings.

Can Qixing customize an FBD seal?

Qixing can review customized and replacement requirements based on dimensions, materials and operating conditions.

FBD Dimension Reference

The table below provides commonly used FBD size references for dimensional matching. Final dimensions should be confirmed against the existing installation before production.