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Gas is in the groove for sealing
New non-contacting mechanical seals from John Crane can greatly improve seal performance on pump applications by reducing operational costs, enhancing reliability, increasing safety and also extending seal life.
Designed for non-turbo, large-bore rotating equipment applications, the Type 2800X dual seals employ patented new technology said to provide environmentally friendly, emission-free sealing.
The 2800X seals have been created for performance-critical applications such as the processing of extremely pure materials where no contamination is permissible, the use of reactive or temperature-sensitive media where local process ‘hot spots’ can cause unwanted chemical reactions, cold applications such as ammonia processing, and air/oxygen-sensitive processes where unwanted oxidation reactions could occur.
The seals have spiral grooves machined into the mating ring faces of the seal heads. As the pump shaft rotates a pressurised inert gas is injected between the faces and compressed as it flows into these grooves. The gas expands again as it leaves the spiral grooves and generates a force which separates the faces to create non-contacting operation. This minimises seal face wear, reduces running and repair costs and extends seal life, and because the gap between the seal faces is kept to a minimum, barrier gas usage is also reduced.
A reverse pressure capability ensures that if the barrier gas fails the process pressure will close the seal faces, preventing any large-scale loss of process fluid to atmosphere. The result is safer and more environmentallyfriendly operation, even under breakdown conditions. The system also eliminates the need for any complex barrier fluid system, which simplifies installation.