Mechanical Seal Flush Plan: Does Your Pump Need One?

When a mechanical seal fails repeatedly, replacing the seal may solve the immediate problem.

But it does not necessarily explain why it failed.

Heat, contamination, solids, poor lubrication conditions and the fluid being pumped can all affect the environment around seal faces.

That is where a mechanical seal flush plan may become important.

Mechanical seal piping arrangements are designed to manage the environment around the seal. Depending on the application, they may provide cooling, remove heat, manage contaminants or circulate suitable fluid through the seal chamber. Flowserve describes seal piping plans as a way to help keep seal faces cool and clean while improving rotating-equipment availability.

What Does a Mechanical Seal Flush Plan Do?

A mechanical seal operates where a rotating shaft passes through the pump casing.

The seal faces work very close together, and the conditions surrounding them matter.

A mechanical seal flush plan can be used to create a more suitable operating environment around those faces.

Depending on the pump, seal and process, that may involve:

• Circulating process fluid

• Introducing a compatible external flush

• Removing heat

• Reducing solids around the seal

• Maintaining appropriate seal-chamber conditions

• Supporting a more specialized seal arrangement

There is no single flush arrangement that is right for every pump.

In fact, some mechanical seal piping plans intentionally operate without an external flush. The correct arrangement depends on the seal design, pumped fluid and application.

When Should You Look Beyond the Seal Itself?

Repeated failures are a good reason.

If a pump goes through mechanical seals more frequently than expected, ask what the failed components are telling you.

Was there evidence of heat?

Was the product dirty or abrasive?

Was material building up around the seal?

Has the process fluid changed?

Has the pump's operating condition changed?

Simply installing another identical seal into the same environment may produce the same result.

Dirty or Abrasive Fluids Need Special Attention

Not every pump handles clean water.

Industrial pumps may move fluids containing suspended material, chemicals, process contaminants or other substances that can affect seal performance.

If particles accumulate around the seal faces, reliability can suffer.

A properly selected seal-support arrangement may help manage the seal environment, but it must be compatible with the application and process fluid. Flowserve specifically notes that piping plans should be selected around the requirements of the individual application.

Heat Matters Too

Seal faces generate and experience heat during operation.

If that heat is not adequately controlled, the seal environment can become less favourable.

That does not mean every warm seal needs an external flush.

It means recurring thermal issues should be investigated as part of the whole sealing system rather than treating the seal as an isolated wear component.

Has the Pump's Service Changed?

A pump may have been selected years ago for one operating condition.

Then the process changed.

Temperature increased.

A different fluid was introduced.

Solids concentration changed.

Pump speed changed.

Operating hours increased.

Yet the seal arrangement stayed exactly the same.

When reliability decreases after a process change, revisit whether the sealing arrangement still fits the application.

More Flush Is Not Automatically Better

This is important.

A mechanical seal flush plan should be engineered for the specific seal and process.

Adding an arbitrary water line to a seal does not automatically improve reliability.

The flush fluid needs to be compatible. Flow and pressure need to be appropriate. The seal arrangement needs to support it.

Some applications require circulation of process fluid. Others use external fluid. Others use different support-system designs entirely.

Look at the Entire Pump System

If seals keep failing, also investigate whether the pump itself is operating properly.

Conditions such as vibration, shaft movement, alignment issues or inappropriate pump operation can affect seals too.

The goal is not simply to find a better seal.

It is to determine why the existing seal is having difficulty surviving the application.

Repeated Seal Failure Is Information

Replacing a mechanical seal once may be ordinary maintenance.

Replacing it over and over should trigger a larger conversation.

A mechanical seal flush plan may be part of the solution, but the right starting point is understanding the pump, process and failure history.

Academy Pump & Motor provides pump sales, service, repair and troubleshooting for commercial and industrial applications throughout Calgary and surrounding areas.

If your pump is experiencing repeated seal failures, call Academy Pump & Motor at 403-437-7888 or visit academypump.ca.