Types of mechanical seals

06.11.2023

What is a mechanical seal?

Before we begin, however, it is essential to have the concept of a mechanical seal in mind. As detailed in this article, a mechanical seal is a device designed to prevent the escape of fluids from a rotating mechanical system. This is vital in a wide range of industrial applications, where even a small leak can cause serious operational and environmental problems.

How many types of mechanical seals are there?

There are basically three main types of mechanical seals: cartridge seals, component seals and air seals. Each of these seals has unique characteristics and specific applications, which make them essential for ensuring the integrity and functionality of various devices and machinery.

Let us analyse each type in detail.

Cartridge mechanical seals

A cartridge mechanical seal is a device designed to provide an airtight seal between two rotating surfaces or between another moving surface and a fixed surface within industrial machinery or mechanical equipment. It is called a 'cartridge' because all of its essential components, including the gland, the sleeve and the necessary hardware, are contained in a single self-sufficient unit, called a 'cartridge'. This configuration offers several advantages:

• Pre-assembly by the manufacturer: the cartridge is assembled and pre-adjusted by the manufacturer. This means that the end user does not have to worry about assembling or adjusting sealing components separately. This greatly simplifies the installation process and reduces the risk of errors.

• Improved reliability: because the cartridge is assembled in a manufacturer-controlled environment, the quality of the assembly is higher and the seal has greater reliability in maintaining its integrity over time.
• Simplified maintenance: when maintenance is required, the manufacturer can provide detailed instructions for replacing the cartridge, which also makes this operation easier. Furthermore, as the cartridge contains all key components, there is no need to dismantle the entire machine or equipment to perform seal maintenance.
• Adaptability to the application: cartridges can be designed to suit the specific requirements of the application. Depending on the sealing requirements, cartridges with one or two seals can be used. This flexibility allows you to choose the most suitable solution for your specific application.

Mechanical component seals

Mechanical component seals are devices used to seal two rotating or fixed surfaces in a mechanical system. This seal consists of two main parts: a separate rotating component and a fixed seat, both mounted in a gland or housing. Unlike cartridge mechanical seals, which are already pre-set and easier to install, component mechanical seals require a greater degree of experience for installation and maintenance.

These types of seals can be more complicated to handle, but offer greater flexibility and adaptability in some specific mechanical applications.

Mechanical air seals

Mechanical air seals are devices designed to seal rotating shafts without coming into direct contact with them. These products are usually used in applications involving dry dust. Their principle of operation is based on the use of minimal quantities of air or inert gas, in order to prevent product leakage, reduce pollutant emissions and prevent contamination.

Mechanical air seals offer several advantages:

• Non-contact: because they do not come into direct contact with the rotating shaft, air seals prevent wear and abrasion, increasing the life and reliability of the system.
• Effective sealing: air or inert gas is regulated to create positive pressure, ensuring an effective seal that prevents the escape of products or contamination.
• Versatile applications: this type of seal is used for a wide range of applications, particularly in environments where product contamination must be avoided, such as in the food or pharmaceutical industries.
• Reduction of emissions: these kinds of seals help to reduce harmful emissions into the environment.
• Maintaining product quality: in contamination-sensitive applications, air seals help preserve product quality by preventing contamination from external particles.
• Energy savings: the lack of friction reduces the need for energy to turn the shaft, helping to save on operating costs.