- 13 December 2007 -
Seals reduce operating costs
John Crane has developed a new range of non-contacting mechanical seals which it says can improve seal performance on pump applications by reducing operational costs, enhancing reliability, increasing safety and also extending seal life.
The Type 2800X dual seals have been designed for non-turbo, large–bore rotating equipment applications and can be used in a wide variety of performance-critical applications. These include 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 feature 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. Because the gap between the seal faces is kept to a minimum, barrier gas usage is also reduced.
The seals have a reverse pressure capability which 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 system also eliminates the need for any complex barrier fluid system.
Pump Industry Analyst
Sealing Technology
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