Separation seals introduced
27 January 2009
John Crane has launched two new separation seals that offer a proven solution to the problems of oil penetrating from a compressor bearing into an outboard gas seal, and the ingress of process gas from the outboard stage of the gas seal into the bearing cavity. The Type 83 and Type 93FR seals are designed primarily for turbomachinery applications and between them they offer a choice of contacting or non-contacting operation.
Both products build on proven John Crane technology and this allows them to offer a number of significant benefits to the end user. John Crane’s testing facilities in the UK - which include a unique vertical shaft movement assessment capability - have been used to complete rigorous testing of the technology that lies behind these seals and they are already finding increasing acceptance from a wide range of international customers.
The Type 83 uses a contacting carbon bushing to isolate the bearing oil from the dry gas seal cartridge. The seal combines advanced materials and design principles which minimise wear and promote improved reliability over a long operational life. The Type 83 is also designed to operate when ultra-dry nitrogen, irrespective of dew-point, is used as the separation gas and injected between the two segmented bushings to create a pressure barrier between the bearing and the dry gas seal cavity.
The Type 83’s universal design accommodates either direction of shaft rotation. It also incorporates a unique carbon bushing segment design with self-adjusting hydropads.
The Type 93FR provides an equally effective and reliable solution to bearing oil ingress into dry gas seals but based on non-contacting operation. It has a floating ring design that incorporates a robust, non-contacting carbon bushing which prevents oil migration, while its advanced design features help minimise wear and heat generation under normal running conditions. This promotes long service life and enhanced reliability.
The Type 93FR runs at a low pressure differential which helps reduce gas consumption, while its self-centering mechanism minimises wear, even during upset conditions. A universal design allows it to accommodate either direction of shaft rotation and the seal can be retrofitted to many traditional separation seal applications.
John Crane is also able to provide fully compatible pressure-regulated control systems for the Type 83 and Type 93FR seals.
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