Types of mechanical seals, carbon and graphite seal faces

We can classify mechanical seals in four categories based on their operation, characteristics, parts that compose them and then the types of mechanical seals that exist.

Conventional seals

Conventional types of mechanical seals are used in devices or applications that are not designed to have mechanical seals. These types of seals are very standardized, as they are intended to be replacements or part of modifications to equipment, such as pumps.

Balanced and unbalanced seals

Hydraulically balanced seals have the diameters of their faces reduced according to the diameter of the shaft where they are installed, thus reducing the pressure load of the pumped fluid on each face. These mechanical seals can be used when dealing with very high pressures or certain types of fluids.

On the other hand, unbalanced seals receive the full force of the hydraulic pressure on both faces, in addition to the spring pressure.

Dynamic or thrust and static or non-thrust seals

Dynamic seals feature an O-ring that moves axially on the shaft by one or two springs that apply force to the seal faces, while compensating for wear and absorbing shaft misalignment.

Non-thrust seals, on the other hand, do not have O-rings, but are stationary but have a bellows that moves to perform their sealing functions.

Cartridge seals

These are self-contained and are already assembled by default. Their installation does not require a lot of time and process investment, making them a great option for shafts without ideal alignment or with the presence of vibrations.

Split seals

Split mechanical seals are mainly used on large shafts, consisting of two parts that are joined together to give a better grip on the shaft. This type of mechanical seals has many applications in addition to solving major problems, such as seal leakage, without the need to disassemble the equipment.

Types of mechanical seals by materials

• Graphite
• Carbon - Graphite, electrographite, electrographite
• Silicon carbide, tungsten carbide
• Alumina - Ceramic
• Graphite impregnated in resin and antimony
• PTFE

Limitations to consider

Performance depends on graphite grade, grain orientation, temperature, load, pressure, speed, and operating environment. Material selection should be confirmed for your actual process conditions.

Information needed for a quote

To guide selection or prepare a quote, ESGRAF typically needs:

• Application and operating conditions (temperature, atmosphere, load).
• Dimensions, technical drawing, or CAD file when applicable.
• Required quantity.
• Requested grade or material currently in use.
• Observed issue with the previous part or lubricant, if any.

Request a quote

Share these details with our team at ESGRAF or request information. A specialist will review your application before recommending a grade or geometry.