Why Genuine Flygt Mechanical Seals Outperform Alternatives

Not all mechanical seals described as compatible with Flygt pumps are equal. The Flygt Griploc and Plug-In seal systems are engineered specifically for the operating environment inside Flygt submersible motors — and the differences between genuine seals and aftermarket alternatives go far beyond dimensional equivalence.

What Makes the Flygt Seal System Unique

Flygt's sealing systems were developed in conjunction with the pump designs they protect. The Griploc seal uses a proprietary locking mechanism that secures the rotating face to the shaft without relying on friction alone — eliminating the risk of the seal spinning on the shaft under high torque or during start-up transients. This feature is absent from generic alternatives that simply adapt standard industrial seal designs to the Flygt shaft diameter.

The Plug-In Seal system goes further by integrating the inner and outer seals into a single cartridge unit. This eliminates the risk of incorrect spacing or misalignment between the two sealing faces during installation. The assembly includes integrated springs, secondary seals, and a protective housing that shields the sealing surfaces from contact with installation tools — a practical design detail that significantly reduces installation-induced damage.

Active Seal Technology

Selected Flygt seal variants incorporate Active Seal technology — a patented feature that makes the inner seal in a double seal arrangement act as a micro-pump. Laser-cut spiral grooves on the inner seal face generate a pumping action that moves fluid from the inner to the outer diameter of the seal ring during rotation. This active displacement prevents fluid from the pump end entering the oil-filled seal chamber, providing an additional layer of protection beyond the passive sealing of the face contact.

This feature cannot be replicated by a generic mechanical seal regardless of face material specification. It is a function of the seal face geometry — specifically the laser-cut spiral groove pattern — that is unique to Flygt's manufacturing process.

Material Specification

Flygt seal face materials are selected for the specific thermal and chemical conditions inside submersible motor housings — not for general industrial pump service. The rotating and stationary face pairings, the elastomer compounds for secondary sealing, and the spring alloys are all specified to perform in an environment of elevated temperature, submergence pressure, and potential chemical contamination from the pumped medium entering the seal housing.

Generic seals use commercial face material grades that meet standard industrial specifications. These specifications are adequate for many applications — but not necessarily for the sustained thermal and pressure conditions that characterise submersible pump operation in wastewater, drainage, and industrial duty cycles.

The Consequence of Using Alternatives

Aftermarket seal failures in Flygt pumps consistently fall into two categories. The first is early face wear resulting from incorrect face material pairing or inadequate face flatness — both caused by commercial-grade manufacturing tolerances. The second is mounting failure — the seal spinning on the shaft or the secondary seal extruding under pressure — resulting from dimensional or material specifications that do not match the Flygt mounting geometry.