The Importance of Seal Support Systems

Selecting and maintaining the right mechanical seal for an operating environment is crucial for preventing leaks and ensuring system reliability. Mechanical seals depend on a thin film of fluid between the seal faces to provide effective sealing. However, for the seal to function optimally, this fluid film must be stable and have appropriate lubricating properties. Seal support systems play a key role in creating the ideal conditions for mechanical seals, helping control factors such as pressure, temperature, and fluid quality.

Common Types of Seal Support Systems

Seal support systems can generally be categorized into three main functions: modifying the process fluid, replacing the process fluid, or controlling the atmospheric side of the seal. Each system is designed to enhance the performance and longevity of mechanical seals under specific conditions.

Modifying the Process Fluid

Some systems modify the process fluid within the seal chamber to stabilize the operating environment:

Plan 11: This system circulates fluid from the pump discharge to the seal chamber, removing heat generated by the seal and increasing pressure. It is simple yet effective for many applications.
Plan 13: This system routes fluid from the seal chamber back to the pump suction, which helps remove heat and vent vapor. It is commonly used in vertical pumps.
Plan 21: Here, process fluid is circulated through a heat exchanger before being returned to the seal chamber, effectively cooling the fluid and stabilizing the sealing interface.

These systems help maintain the proper fluid conditions necessary for efficient mechanical seal operation by controlling heat, pressure, and cleanliness.

Replacing the Process Fluid

In cases where the process fluid is inadequate for seal lubrication, external fluids can be introduced:

Plan 32: This system pumps an external fluid into the seal chamber, displacing the process fluid and removing contaminants.
Plan 53: In this system, a closed-loop barrier fluid is maintained at a higher pressure than the process fluid. This pressurized barrier prevents leakage, ensuring the seal remains effective in more demanding applications.

By using external fluids, these systems create an optimal environment for mechanical seals, especially in processes with harsh or unstable fluid conditions.

Controlling the Atmospheric Side

Seal support systems can also manage fluid leakage and protect the seal’s external environment:

Plan 62: A fluid (such as steam or nitrogen) is applied to the atmospheric side of the seal to prevent product crystallization or coking.
Plan 65: This system collects liquid seal leakage in a reservoir, allowing for leakage monitoring and preventing environmental contamination.

Seal support systems are essential for optimizing mechanical seal performance and ensuring system reliability. By modifying the process fluid, introducing external fluids, or controlling leakage, these systems help maintain optimal operating conditions and extend the lifespan of mechanical seals.

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