Type 28 compressor dry-running gas seals have been the industry standard since early 1970 for gas-handling turbomachinery. Utilizing John Crane’s patented spiral groove pattern, these seals are non-contacting in operation. During dynamic operation, the mating ring and primary ring maintain a sealing gap of approximately 0.0002"/5 microns, thereby eliminating wear. These seals eliminate seal oil contamination and reduce maintenance costs and downtime. Single, tandem and double seal arrangements are available.
Type 28XP: Possibly the most popular seal in the range today, the Type 28XP builds on the 28AT design and seals medium to high pressures with improved chemical resistance. It can also operate over a wider temperature range and is increasingly the preferred product for large sizes, and for applications requiring slow roll and coast-down where dry gas (very low dew point) conditions and rotational speeds lower than the lift off speed of the gas seal create arduous contacting operation. Type 28XP seals are also available with Carbon LF™ primary ring material for improved friction and wear-resistance for contacting operation in dry gas (very low dew point) conditions.