With non-contact seals, the surface shape of the seal determines the ability to create a stable gas or liquid film. The article summarizes some surface technologies announced by Flowserve, along with explanatory principles added by SNS-VN.
When the seal face with grooves or special shapes rotates, gas or liquid is drawn into the gap and creates pressure to push the two faces apart. The film thickness self-balances: the film becomes thinner, the pressure increases to push the face away, the film becomes thicker, the pressure decreases. Thus, the seal maintains a very small gap without touching each other.
The Gaspac dry gas seal uses one of two groove patterns: T-Groove bidirectional or Advanced Pattern Groove (APG). According to the manufacturer, both create a gas film with high stiffness and damping capability, maintaining a stable gas film at slow speeds and high speeds up to 250 meters per second. The bidirectional groove works when the shaft rotates in both directions, while the unidirectional groove is often optimized for one direction of rotation.
The QBQ LZ seal uses Precision Face Topology technology, a patented wavy seal face, to significantly reduce diffusion leakage in light hydrocarbon service.
The GX-200 seal uses the APG groove pattern combined with a metal bellows, creating hydrostatic and hydrodynamic lift forces to keep the seal face non-contact. The manufacturer claims that the seal achieves zero emissions, even when running dry, and can be installed in standard seal chambers without modifying the pump.
Product documentation from Flowserve, AIChE. The article was compiled and reinterpreted by SNS-VN; brand names belong to their respective owners.