Skip to main content

John Crane's Type 28 Dry Gas Seals: How Does It Work?

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 fluid film stiffness and providing the highest possible degree of protection against face contact. Riding only on the load support of a cushion of gas, the seal's film stiffness compensates for varying operating conditions by adjusting the gap and pressure generated to maintain face stability.
John Crane Type 28 seal designs include:
  • Type 28AT Advanced Technology: Designed to excel in low pressure applications, the 28AT is today's most widely used non-contacting, dry running gas seal. Its design pedigree stretches back over 30 years and it has been proven in use on many thousands of installations around the world. The versatility offered by the 28AT makes it ideal for a very wide variety of gas compressor applications.
  • Type 28XP High-Pressure: Offers all the features and benefits of the 28AT, but is optimized to provide reliable performance on higher pressure duties. The 28XP's increased chemical resistance and ability to operate over a wider temperature range has established it as an industry benchmark for reliability.
  • Type 28EXP Extreme High Pressure: John Crane's highly effective solution for sealing gas installations that involve extreme pressures. It has been proven in use in the most challenging and hostile environments and delivers rugged and reliable performance around the world.
  • Type 28ST Steam Turbine: The non-contacting, steam lubricated Type 28ST is an effective sealing solution for small to medium-sized general steam turbine applications. By combining proven rotating groove technology with a high-temperature capability that virtually eliminates leakage of steam along the shaft, it creates an excellent alternative to traditional sealing devices such as segmented carbon bushes and labyrinths.
  • Type 28VL Vaporizing Liquids: Uses the energy of the rotating equipment to vaporize process fluid at a controlled rate, creating a gas film that lubricates the seal faces in applications of extremely low temperature.
  •  

What Sets The Type 28 Series Apart?
  • Accurate centering and balancing: The Type 28 seal mating ring and sleeve use tolerance rings to provide precise centering and cushioning. The seal runs true with a dynamically balanced rotor assembly that eliminates vibration.
  • High-pressure support capability: A metal carrier in the Type 28XP seal controls distortions that can occur under high-pressure loads.
  • Low-drag ring assembly: A custom-fit o-ring and thrust ring set provides extremely low drag and uniform loading to the primary ring surface.
  • Reduced-stress drive points: Low-stress drive flats on the Type 28 seal eliminate stress riser pin holes found in other designs.
Labels:

Comments

Post a Comment

Popular posts from this blog

Dry Gas Seal Failure Modes

BY BHUSHAN NIKAM. Invented in the mid-20th century and typically equipped in process gas centrifugal, dry gas screw compressors and expanders, dry gas seals (DGS) are the preferred gas lubricated dry seal solutions available on the market. They have become the standard for new machines. DGS are robust, simple, consume less power, and are more efficient in reducing leakage than their predecessor. Various configurations such as tandem with and without an intermediate labyrinth ( Figure 1 ), single ( Figure 2 ), and double ( Figure 3 ) are available & shall be selected based on process requirements. In this article, we discuss the various DGS failure modes and how they should be addressed:  PRESSURIZED HOLD/STANDBY Pressurized hold, also called settle-out condition, occurs when the compressor remains at a standstill, but the casing is pressurized. If an alternate process gas lacks sufficient pressure and flow, process gas enters the seal cavity through the process labyrinth ...
Post a Comment
[Read more...]

Understanding the Causes of Pump Shaft Breakage

By NTS. Pump shafts are essential in many industrial and commercial applications, providing the necessary mechanical force to move fluids through pipelines and process systems. However, when a pump shaft breaks, it can cause significant downtime, production losses, and safety risks. In this article, we will explore the common causes of pump shaft breakage and how to prevent it from occurring. 1. Excessive Load  The most common cause of pump shaft breakage is excessive load. When a pump is overloaded, it places a significant amount of stress on the shaft, causing it to bend, warp, or break. Overloading can be caused by a variety of factors such as a clogged discharge line, worn impeller, or damaged bearings. Proper maintenance, regular inspections, and monitoring of the pump's performance can help prevent overloading. 2. Misalignment  If the pump and motor are not properly aligned, it can cause stress on the pump shaft and lead to breakage. Misalignment can occur due ...
Post a Comment
[Read more...]

5 Important Maintenance Metrics and How To Use Them

By  Bryan Christiansen,  Limble CMMS. Source : maintworld.com Effective maintenance of equipment is a critical factor in delivering quality operations that provide timely resources at a minimal cost. However, those in the maintenance field understand that equipment reliability does not come easy.  Organizations need to set quality benchmarks to measure the current effectiveness and predict future performance and use the data obtained to understand where to make improvements.   One way to do this is by using different maintenance metrics to understand the equipment performance. These metrics are very important as they can mean the difference between achieving the overall business goals and explaining how unexpected breakdowns caused yet another production delay.   Maintenance Metrics You Should Be Measuring What are the maintenance metrics? There are two categories of maintenance key performance indicators which include the leading and lagging indicators....
Post a Comment
[Read more...]

Top 8 Reasons for Mechanical Seal Failure and How to Prevent Them

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...
Post a Comment
[Read more...]

Technical questions with answers on gas turbines

By NTS. What is a gas turbine? A gas turbine is an engine that converts the energy from a flow of gas into mechanical energy. How does a gas turbine work? Gas turbines work on the Brayton cycle, which involves compressing air, mixing it with fuel, and igniting the mixture to create a high-temperature, high-pressure gas. This gas expands through a turbine, which generates mechanical energy that can be used to power a variety of machines and equipment. What are the different types of gas turbines? There are three main types of gas turbines: aeroderivative , industrial, and heavy-duty. Aeroderivative gas turbines are used in aviation and small-scale power generation. Industrial gas turbines are used in power generation and other industrial applications. Heavy-duty gas turbines are typically used in large power plants. What are the main components of a gas turbine? The main components of a gas turbine include the compressor, combustion chamb...
Post a Comment
[Read more...]