Why the groove makes all the difference

In a separation seal design, scaling is often underestimated. Making a mechanical seal larger or smaller may look straightforward, but delivering the same performance at every size is anything but. The real challenge isn’t changing dimensions; it’s preserving behaviour.

That’s because in real applications, performance does not automatically scale with geometry.

Why scaling a mechanical seal is so challenging

Coaxial separation seals must fit into tightly defined cavities, interface with fixed hardware, and operate within strict axial and radial limits. These constraints mean that clean, proportional geometric scaling is rarely possible. Individual features cannot be scaled independently; their dimensions are tightly linked to surrounding geometry and to the force balance that governs how the seal behaves in operation.

At the same time, changing size alters the physics. Surface speed changes for a given shaft speed, opening forces scale with area, and pressure distributions across the seal face shift. Without careful control, these effects can soften the gas film, reduce stiffness or introduce instability, even when the seal looks geometrically familiar.

This is why seals that appear geometrically similar can behave very differently once installed and running.

Same physics, different scale

Scaling a separation seal is similar to scaling any dynamic mechanical system. Changing the size alters how forces, stiffness and flow interact. Unless those relationships are preserved, the system may look familiar but behave very differently.

Mechanical seals are no exception. Scaling geometry alone does not guarantee the same force balance or dynamic response. The real objective is to preserve the behaviour of the gas film: how opening force develops as the gap tightens, how stiffness increases under load and how the film responds to changes in speed and pressure.

This is why dynamic similarity, not geometric similarity, is the key to scalable seal performance.

Scaling the physics

For the Type 93AX coaxial separation seal, scalability starts with the physics. The design focuses on maintaining the same force balance and fluid-film behaviour at every size, even when the geometry must adapt to fit the application.

From a fluid-dynamics perspective, this means preserving the operating regime inside the groove. Key non-dimensional parameters, such as Reynolds number, are used to ensure that flow behaviour, pressure distribution and film response remain consistent as the diameter changes. By maintaining these relationships, the gas film reacts to load and motion in the same way, regardless of scale.

The result is a film that stiffens as the gap tightens, responds predictably to changing conditions, and remains stable across the operating range.

Consistent behaviour, independent of size

By combining geometric adaptation with dynamic similarity, the T93AX separation seal scales without losing what makes it reliable.

Across different diameters, the seal faces remain stable, the opening force increases predictably as the gap reduces, leakage paths at the inner and outer diameters stay healthy, and operating temperatures remain controlled. In practical terms, the seal behaves the same way in service, whether it’s installed in a compact unit or a large, high-power compressor.

That consistency isn’t just expected; it has been proven. Six different seal sizes were prototyped, tested and validated to confirm that the scaling laws applied preserve the intended force balance and fluid-film behaviour. Across these sizes, the same dynamic response, stiffness characteristics and stable operating behaviour were observed, demonstrating that the physics scales as designed, not just the geometry.

What this means for mechanical seal reliability

For operators and OEMs, proper scalability removes uncertainty. A seal that preserves its dynamic behaviour across sizes reduces risk, simplifies qualification and improves confidence during design changes or upgrades.

Instead of rediscovering seal behaviour at every new diameter, the same proven performance carries forward. The seal does what it’s designed to do, consistently and predictably.

Designed to scale, engineered to perform

Scaling a separation seal correctly requires more than resizing components. It demands a deep understanding of force balance, fluid dynamics and dynamic response, and the discipline to preserve those relationships as geometry changes.

By focusing on the physics rather than proportions, the Type 93AX coaxial separation seal delivers the same stable, self-correcting behaviour at every size. No additional tuning. No unexpected behaviour. Just reliable performance, scaled with confidence.

When reliability matters, size shouldn’t change the outcome.