Dry gas seal is a non-contact seal, using an extremely thin gas membrane between the two seal faces to seal the compressor shaft. Because it does not wear out during operation, the seal has low friction, long lifespan and very small leakage. This article explains how it works, its advantages and disadvantages, and when to use it.
The seal consists of a rotating ring attached to the shaft, with very small spiral grooves on the ring surface, a stationary ring attached to the machine body, a spring pressing the two rings together, and auxiliary gaskets. When the machine stops, the spring keeps the two faces in contact to seal.
When the shaft rotates, the grooves pump gas into the gap and create a lifting force that pushes the two seal faces apart, with a gap of only a few micrometers. This gap self-adjusts to balance the force, so the seal does not contact during normal operation.
The seal requires a gas control panel for filtration, pressure regulation and flow measurement of supply gas. The quality of supply gas is a decisive factor for reliability.
The seal is sensitive to solid particles and liquids entering the gap, requires clean and dry gas, and attention is needed during machine startup and shutdown. The initial investment and support system are higher than conventional seals.
Supply gas must be clean, dry and have higher pressure than the seal chamber. The support system must be designed correctly according to compressor conditions. Contact SNS-VN for consultation.