KLS High Performance Lip Seals
KLS® seals are hydrodynamically lubricated, spring-loaded, high performance lip seals. They were developed for high-pressure applications that rotate primarily in one direction, such as oilfield rotary control devices (RCDs). One thing that sets KLS seals apart from typical Kalsi Seals is that they do not require a pressurized lubricant. This allows them to be used in simpler, lower cost RCDs that do not have a complex lubricant pressurization system.
The dynamic lip of the KLS seal is composed of rubber and plastic layers, and is loaded against the rotating shaft by a V-shaped metal spring. The plastic layer provides extrusion resistance, and defines hydrodynamic waves at the low-pressure end of the seal. During rotation, the unique shape of the waves forces a film of lubricant between the plastic layer of the seal. This interfacial lubrication minimizes wear and seal-generated heat, and allows the rotary seal to operate with significant differential pressure acting from the spring side.
The qualification testing of the KLS seal was performed at a surface speed of 545 feet per minute, with pressures up to 1,000 psi acting from the spring side of the seal. Seal condition was still good after tests that exceeded 200 hours of 1,000 psi operation. This speed and pressure combination is far beyond the capacity of non-hydrodynamic seals with otherwise identical design configurations. The seals have also been successfully tested at 1,500 psi and 136 feet per minute. The remarkable pressure capacity of KLS seals has made them one of the rising stars of the Kalsi Engineering product line.
When used to contain a non-abrasive pressurized fluid, only one KLS seal is required, along with a simple gravity-fed lubricant supply, such as the bearing lubricant of the rotating shaft seal assembly. When the pressurized fluid is abrasive, such as in an oilfield RCD, then a pair of KLS seals is recommended. The lubricant between the pair of RCD seals should be balanced to the pressure of the pressurized fluid using one or more small pistons or diaphragms. The lubricant above the pair of seals can simply be gravity fed from the bearing chamber. With this arrangement, no external lines or lubricators are required. If desired, however, the low pressure bearing lubricant can easily be circulated for cooling purposes.
The reason a pair of KLS seals is recommended for abrasive service is because the abrasion resistance of lip seals becomes far less reliable as differential pressure increases. At the same time, the abrasion resistance of lip seals exposed to little or no differential pressure is typically excellent, even with shaft runout of 0.010” FIM (click here for test results). With the recommended implementation, the outboard seal that is exposed to the abrasive fluid on one side operates at low differential pressure, and the inboard seal that is exposed only to lubricant operates at high differential pressure.
For more information, to discuss how to use KLS seals in your rotating shaft seal assembly, or to purchase KLS seals, contact us by telephone (281-240-6500) or submit a contact form.