rotary seals
- September 18, 2018
Gallagher recently recorded the Rubber Energized Seals webinar, discussing rubber energized rod or piston seals, and the advantages and disadvantages to using some of the most common seal profiles. This webinar is presented in conjunction with one of our trusted partners, Eclipse Engineering, Inc.
- August 23, 2016
Today we’ll continue our look at spring-energized seals by exploring some of the preliminary considerations to made when working with these seals.
A spring energized PTFE seal is selected to fit an exact set of service conditions found in your application.
Gallagher Fluid Seals recommends conducting a review of the entire sealing environment. You should use the Engineering Action Request (EAR) form before selecting a seal design.
- April 21, 2016
Today we’ll conclude our series of blog posts on PTFE by discussing some PTFE radial lip seal applications, as well as a brief look at wear sleeves.
PTFE has superior mechanical and physical properties and chemical resistance, which means the areas where PTFE radial lip seals are used is growing. These areas include:
Diesel Engine Applications
These consist of the front and rear crankshaft, accessory drive, and blower and thermostat seals. PTFE seals are used and tested in these areas because they can meet the performance and life requirements of modern engines.
Minimum wear, performance at high temperatures with limited lubrication, resistance to abrasive contaminants and fluid compatibility are the main factors for PTFE’s use in these applications.
- April 14, 2016
Today we’ll continue our look at PTFE rotary seals by focusing on three areas: housing/bore considerations, pressure and shaft velocity and shaft misalignment and runout.
Housing/Bore Considerations
Typical PTFE rotary lip seals are pressed into the bore to assure proper OD sealing and seal retention in the housing. Most seal and housings are made from steel and cast iron. Take care when softer materials – aluminum, bronze, plastic – are used for the housing. Aluminum has a thermal expansion rate almost double that of steel. Metal case designs can lose the required press fit in an aluminum housing when they go through thermal cycles due to the higher rate of thermal expansion of aluminum.
A finish range of 32 to 63 μin Ra (0.8 to 1.6 μin Ra) is recommended for service pressures up to 3 psi (0.20 bar). For thicker fluids such as grease, a 125 μin Ra (3.17 μin Ra) finish would be acceptable with no system pressure.
A lead in chamfer is strongly recommended for all seal housings. The chamfer aligns the seal during installation and helps keep the seal from cocking. Both corners of the chamfer should be free of burrs or sharp edges. For pressurized rotary applications, take additional precautions to ensure the seal isn’t pushed from the housing.
- March 29, 2016
As we continue this blog’s PTFE series, we’re going to take a closer look at PTFE rotary seal shaft considerations.
In rotating applications, proper surface finish is crucial for getting positive sealing and the longest seal life possible. Rotating surfaces that are too rough could create leak paths and can also be very abrasive. Unlike elastomer contact seals, PTFE lips can run on very smooth surfaces regardless of lubrication.
- March 10, 2016
Over the past few weeks, we’ve gone into a lot of detail about how PTFE rotary lip seals work.
Today we’ll offer up a short glossary of some of the terms used when discussing these seals. We'll also break down some of the factors affecting PTFE rotary lip seal design.
- February 23, 2016
Over the past few weeks, we’ve been discussing the basics of PTFE rotary seals. In today’s entry, we’ll take a look at PTFE radial lip seal design principles.
PTFE radial lip seals generally incorporate a uniformly thin element cross section, made to compensate for the high flexural modulus of PTFE, especially in cases of severe shaft run-out. The thin sections also minimize thermal expansion and compressive “creep” and their effects on maintaining a controlled contact pattern on the shaft surface.
Most PTFE seal constructions have the “body” portion of the element clamped between the two metal cases. To maintain proper retention pressure on the element, a thin element keeps compression set and “creep” at a minimum.
- January 14, 2016
In our last blog post, we talked about some of the benefits and uses of PTFE rotary lip seals.
But how do PTFE rotary seals work? In this post, we’ll try to answer that question in more detail.
Rotary shaft seals work by squeezing and maintaining lubricant in a slim layer between the lip and the shaft. Sealing is aided by the hydrodynamic action caused by the rotating shaft, which creates a slight pump action.
- January 12, 2016
PTFE resin was discovered in 1938, but it wasn’t until the 1950s that it gained notice as a possible rotary lip seal material. However, PTFE (polytetrafluoroethylene) seals fell out of favor in the 1950s and 1960s, as they were shown to be unreliable performers in a number of applications.
In more recent decades, there has been significant progress in the areas of PTFE lip seal design and material processing.
- October 13, 2015
In the world of sealing, it seems as though there are as many varieties of pump applications as there are sealing solutions.
Many breakthroughs in technology have aided the evolution from braided packing to advanced mechanical seals, leading to remarkable gains in pump performance, efficiency and safety. Although mechanical seals are certainly a fitting solution for an array of pump and rotary applications, advances in polytetrafluoroethylene (PTFE) rotary lip seals can also solve these challenging radial sealing solutions.
Radial lip seals can retain lubricants and excluded unwanted contaminants for a fraction of the cost of a mechanical seal, while providing many of the same benefits in terms of performance and seal life.