In a centrifugal pump, a component or cartridge seal may be interchanged, depending on the application. By understanding the advantages and disadvantages of each, you can ensure the optimal performance of your pump.
Component Mechanical Seals
Most standard mechanical seals fall under this category. Replacements of these seals typically include seal faces, holding brackets, O-rings, boots, and parts which must be installed by an experienced pump technician. This is important, as the seal housing’s limited access requires a precise and accurate hand. If just one component is installed incorrectly, the risk of seal failure will increase significantly. There are many components of the seal which need to be installed just right, including seal faces which must be properly seated on the shaft or seal housing, and sliding O-rings and elastomers over shaft shoulders, key ways, and other parts. A mistake installing any of these parts can result in misalignment, damage, and incorrect seal tension.
Cartridge Mechanical Seals
While cartridge seals share many components in common with component seals, there are a few essential differences. Some of the parts come preassembled, like the stationary components which come in a housing; and the rotating components, which come on a shaft-mounted sleeve and are sealed with an O-ring or elastomer. Because of this, installation errors are far less likely.
A key part of successful seal installation is setting the spring tension. Component seals are set manually by adjusting the length of the seal’s spring. Cartridge mechanical seals, on the other hand, have preset spring tensions. A retaining device is used during the installation process to hold the rotating and stationary elements in alignment.
Whether you will be able to install a cartridge mechanical seal will depend on many complex factors affecting the pump. One of the main factors is which side the seal installs from. Most cartridge mechanical seals cannot be installed on the wet side of a pump’s seal chamber, behind the impeller. These seals are generally incompatible with submersible pumps for a similar reason.
Comparing the Two
Deciding between the two seals largely depends on the cost and ease of installation. While the presence of a competent pump technicians might make ease of installation seem like a non-issue, being able to replace a seal during an emergency outage should be a concern.
Unfortunately, cartridge seals cost two to three times more than component seals, so most competitive repair bids you will see often refer to component seals. Although they cost more upfront, in the long-term, cartridge seals are more cost-effective. While component seals require in-service replacement, cartridge seals require less labor costs and less production lost from seal replacement. You’ll also save money on potential errors resulting from potential installation errors of component seals.
In short, mechanical seals are the best choice for users who need a long-term, cost-effective solution for pump maintenance, while component seals are best-suited for users who place a higher priority on a lower upfront cost. For more information or seals and other related components, visit Real Seal.
