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Dry-Running Sealing Technology: Pump Applications (P1)


Non-contacting, dry-running seal technology, a revolutionary technology for pumping equipment, was developed and pioneered by John Crane and meets the USA Clean Air Act of 1990. This Act defines emission standards for rotating equipment. Designed for emissions control, this sealing concept has resulted in improved reliability, efficiency, and cost benefits when compared to competing technologies such as canned and magnetic drive pumps.

A non-contacting, dry-running seal solves the tribological problems when pumping certain fluids rather than transferring those problems to other areas of the equipment as in the case of competing technologies.

Many plant operators have a Mean Time Between Planned Maintenance (MTBPM) of less than two years. In some cases, equipment is down for repair every two to three months. This has a major impact on the cost of owning the equipment and may also impact the amount of product being manufactured. By properly applying non-contacting, dry-running seal technology, the benefits in improved reliability are significant.


What the User Expects

The user expects exceptional performance throughout the life of the equipment. Running a plant with fewer operators and mechanics means the complete pumping system must run when it is needed and last a long time. The pump must operate safely and meet existing regulations while reducing cost. Pump and seal systems are vital to a plant’s operation. They must be carefully selected for each application to achieve the design reliability.

Causes for Short Seal Life

At the 1997 International Pump User’s Symposium in Houston, TX, users attending a forum on mechanical seals were asked to identify the causes for short seal life at their plant. The problems identified were:

· Improper operation of the pump
· Dirt flushed in the seal chamber
· Start-up without venting
· Vibration of equipment
· Misalignment/pipe strain
· Worn seal chamber bushing
· Pump control/level flow control
· Installation
· Loss of seal flush
· Cavitation
· Process problems
· Low NPSH
· Dry run

Solutions to Common Problems

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