Industrial Maintenance Solutions

Mechanical seals are critical components of pumps, responsible for maintaining a fluid-tight seal between the rotating shaft and the stationary pump housing. However, these seals can fail due to various factors, leading to leakage, reduced pump efficiency, and costly downtime. In this article, we will discuss the top reasons for mechanical seal failure in pumps and how to prevent them. 1-Improper Seal Selection Choosing the wrong mechanical seal can cause it to fail. Consider the following factors that can contribute to seal failure: • Chemical compatibility: All seal components, such as the seal faces and O-rings, must be compatible not only with the process fluid being pumped, but also with non-process fluids used for cleaning, steam, acid, and caustic flushes, etc. • Physical degradation: Using soft seal faces on abrasive liquids will not last. Shear-sensitive liquids, like chocolate, can break down and leave behind solids (such as cocoa powder) and force out liquids (like oil). • S...

How Does It Work? Highest Pressure Non-Contacting, Dry-Running Gas Seal Type 28 compressor dry-running gas seals have been the industry standard since the early 1980s for gas-handling turbomachinery. Supported by John Crane's patented design features, these seals are non-contacting in operation. During dynamic operation, the mating ring/seat and primary ring/face maintain a sealing gap of approximately 0.0002 in./5 microns, thereby eliminating wear. These seals eliminate seal oil contamination and reduce maintenance costs and downtime. John Crane's highly engineered Type 28 series gas seals incorporate patented spiral-groove technology, which provides the most efficient method for lifting and maintaining separation of seal faces during dynamic operation. Grooves on one side of the seal face direct gas inward toward a non-grooved portion of the face. The gas flowing across the face generates a pressure that maintains a minute gap between the faces, optimizing flui...

Solutions to Common Problems The operation of a single contacting seal would be difficult with any of the identified problems. A single contacting seal relies on cooling and lubrication from the process liquid being sealed. Any interruption in the cooling and lubrication processes will result in damage to the seal and leakage to the environment. The non-contacting, dry-running seal is a solution to many of the problems identified by users. An installation to a pump is illustrated in Figure 2. This type of pump seal technology does not require the circulation of liquid for cooling. Instead, a static heat of an inert gas is used to pressurize the space between the seals. Nitrogen gas in normally used to create the barrier between the process liquid and the environment. The gas barrier pressure is normally 20 to 30 psi/1.4 to 2 bar above the seal chamber pressure.  The spiral groove geometry of the seal face is responsible for lift-off and separation of the seal f...

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...