Category Archives: elastomeric seals

Solving High-Pressure, High Eccentricity Seal Issues

Facing challenges, head-on is what Vanseal does every day – which is why their customers trust them to deliver tested and proven, material and design solutions that improve the performance of their seals, no matter how tough the environment.

High-Pressure, High Eccentricity Seal Solution Demonstrates 50% Improvement

– On pressure and side-load performance of a fluid application

Recently, a customer was having difficulty with a seal failure on apicture of leoader fluid power application. The high-pressure, high-eccentricity seal operates in conditions up to 200,000 pv at 3000 psi and could not exceed maximum shaft deflection of 0.005″.

Vanseal works with these types of seal applications frequently and used a Unitized Seal that uses several components to address each of the various sealing challenges.

Vanseal’s solution for its high-pressure, high-eccentricity seal incorporated these key elements:

  • Primary Seal Lip – Made from a high-modulus elastomer, to reduce lip extrusion and inversion under pressure, better distributing high-pressure forces to enhance sealing
  • Machined PTFE Backup Lip – Used to reduce the risk of extrusion and inversion of the Primary Seal Lip
  • Support Washer – Designed to close the extrusion gap between the seal ID and shaft under high, shaft-deflection conditions
  • Excluder Lip – Works to keep contaminants from entering the assembly system
  • Metal Case – Serves as a carrier for the seal components creating a single unit to install, and thus reducing instances of installation errors caused by multi-piece installations and reducing individually purchased and inventoried items.

Vanseal has been manufacturing highly specialized seal components for over 60 years

  • Sealing systems are tricky and using a stock seal manufactured for typical high-pressure applications may not be enough to absorb high-shaft deflection.
  • Our experienced engineers have in-depth knowledge on how to address these difficult sealing challenges.
  • Along with engineering, we maintain the highest standards in quality testing and manufacturing methods.

The original article can be found on Vanseal’s website.

To learn more about Vanseal’s products, speak to a Gallagher representative today by calling 1-800-822-4063

The Basics of Microwave Absorber Materials

Article re-posted with permission from Parker Hannifin Sealing & Shielding Team.
Original content can be found on Parker’s Blog.


You’ve probably heard a bit about microwave absorbers and how they are used to reduce or absorb the energy that is present in a microwave. But what are they exactly? And how do they work? Go ahead, read on.

What are microwave absorbers?Picture of Microwave Absorber

Simply put, microwave absorbers are special materials, often elastomer or rubber based, which are designed to offer a user-friendly approach to the reduction of unwanted electromagnetic radiation from electronic equipment. They also work well to minimize cavity to cavity cross-coupling, and microwave cavity resonances. When comprised of a silicone elastomer matrix with ferrous filler material, microwave absorbers provide RF absorption performance over a broadband frequency range from 500 MHz to 18 GHz.

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A Guide to Elastomer Technology in Mechanical Seals

Elastomer Technology in Mechanical Seals

Evaluate properties of rubber during installation and seal life.

Elastomers (or rubbers) are a ubiquitous family of materials whose use stretches across nearly the entire range of mechanical seal designs.  From plant-sourced natural rubber, so named by John Priestly in 1770 for its utility in rubbing away pencil graphite, to petroleum-sourced synthetic rubber first developed around the turn of the 20th century, the “elastomer” and their properties are familiar but should not be overlooked—especially when dealing with mechanical seals.

How Elastomers Work in Mechanical Seals

Rubber seals come in a variety of profiles—O-rings, cup gaskets, bellows diaphragms, sealing/wiper lips and many others. They are classified as either static or dynamic and create positive pressure
against surfaces to eliminate or control the leakage of liquids and/or gases while preventing the entrance of external contaminants such as dust and dirt. Static sealing occurs between adjacent surfaces with no relative motion, such as between the pump casing and cover. Due to frictional wear and heat generation, dynamic sealing is less straightforward, occurring between adjacent surfaces that are continuously or intermittently moving relative to another, such as between the pump casing and shaft.

In mechanical face seals, elastomers tend to take second chair because the primary seal—the dynamic seal between the housing and rotating shaft—is achieved by sliding contact between the pair of stiffer, lapped-flat sealing faces, one stationary in the housing and one rotating with the shaft. In many designs, rubber provides the secondary seal between each seal face and adjacent surface. One seal face is fixed and sealed statically using an O-ring or cup gasket. The other is spring-loaded and requires a semi-dynamic seal to accommodate some axial play, such as a dynamic O-ring in pusher-type mechanical face seals or elastomeric bellows in nonpusher ones. These semi-dynamic applications (involving flexing and sliding of the elastomer) can be critical for maintaining proper contact between the faces through face wear, shaft movement, etc.

Although the seal face pair tends to be the most critical design feature, mechanical face seals are  often used in the most demanding applications.

Rubber technology features prominently in radial lip seals, where typical applications have lower pressurevelocity (PV) values relative to those involving mechanical face seals. Still, the flexible elastomer lip must handle considerable relative motion in the form of shaft/bore rotation, reciprocation or a combination of both. In addition to standard designs and sizes, numerous customizations and proprietary approaches exist. The simplest designs rely on a single rubber lip’s inherent resiliency, although common enhancements include multiple sealing lips, a circumferential garter spring installed in a groove over the sealing lip to maintain contact with the shaft, and an auxiliary wiper lip or “excluder” to prevent abrasive dust or debris from compromising the primary sealing surface. For improving service life and performance in rotary applications, unidirectional or bidirectional hydrodynamic pumping aids can be added in the form of custom-shaped extrusions on the backside of the sealing lip to return leaked fluid to the sealing interface, increase lip lubrication and lower operating temperatures.

Diagram of secondary, dynamic elastomeric seals in mechanical face seals.

Benefits of Rubber

The definition of an elastomer provides initial insight into where rubber gets its resilient sealing quality: “a macromolecular material which, in the vulcanized state and at room temperature, can be stretched repeatedly to at least twice its original length and which, upon release of the stress, will immediately return to approximately its original length.”

When the rubber is squeezed by the adjacent surfaces of the clearance gap to be sealed, it has the characteristic
properties of malleably deforming and taking the shape of each  surface in response to the stress and applying a force back against the surfaces in its attempt to return to its original dimensions. Elastomers consist of large molecules called polymers (from the Greek “poly” meaning “many” and “meros” meaning “parts”), which are long chains of the same or different repeating units, called monomers, usually linked together by carbon-carbon bonds (the
most notable exception being silicone elastomers, which are linked by silicon-oxygen bonds). Soft and hard plastics are also composed of polymers. However, the regularity of the monomers in their polymer chains allows neighboring segments to align and form crystals, making the macromolecular plastic material rigid and inelastic.

One can prevent this crystallization by breaking up the regularity of the polymer chain, resulting usually in a viscous “gum” that is readily shaped into molds. At the molecular level, the polymer chains are similar to spaghetti-like strands flowing past each other.

During the process of vulcanization, Representatin of three polymer chains after formation of crosslinking via vulcanizationor curing, the viscous liquid is heated with sulfur or peroxides and other vulcanizing agents, and crosslinks form between polymer chains, tying them together with chemical bonds, converting the gum into an elastic, thermoset solid rubber that retains its shape after moderate deformation.

In addition to the selection and preparation of base polymer(s) and cure system ingredients, formulating the final rubber product, also known as compounding, involves five other broad categories of ingredients, which have percentage compositions expressed in parts per hundred rubber (phr). Fillers include various powders that thicken the polymer mixture, improve strength and resistance to abrasives, and reduce final cost. Plasticizers are oils and other liquid hydrocarbons that lower viscosity to ease processing, soften the final compound and in some cases improve low temperature performance. Process aids are specialized chemicals added in low concentrations to improve mixing, flow properties and final appearance.

Antidegradants protect the rubber from environmental attack. Finally, various miscellaneous ingredients may be added for special purposes, including foaming agents, dyes, fungicides, flame
retardants, abrasives, lubricants and electrically conductive particles. A simplified description of processing these ingredients includes mixing via tangential or intermeshing mixers, forming into desired shapes and vulcanizing into the final product.

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Selection Requirements for Elastomeric Seals

Selection Requirements for Elastomeric SealsGallagher Fluid Seals is a proud of its longtime partnership with DuPont®, having specified thousands of perfluoroelastomer parts over the past few decades.

DuPont is at the forefront of perfluoroelastomer development, creating elastomers with properties that can help meet highly specific application requirements.

But how do you know which elastomer is right for your application? DuPont provides this helpful guide.

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Elastomer or Plastic… Which Should You Choose?

Kalrez KLX-16011Gallagher Fluid Seals is a longtime partner of DuPont®’s, having specified thousands of DuPont perfluoroelastomer parts over the past few decades.

While elastomers were originally created as an alternative to natural rubber, they have expanded to include materials such as high-performance perfluoroelastomers for demanding applications.

These materials can also be used in place of plastics in most, if not all, applications. DuPont is at the forefront of perfluoroelastomer development, creating elastomers with properties that can help meet highly specific application requirements.

Read on to learn more from Dupont about the differences between elastomers and plastics, and how elastomeric seals perform compared to plastic seals.

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What is a Spring Energized PTFE Seal?

spring

Spring energized PTFE seals perform reliably in a variety of applications where conventional elastomeric seals fail due to chemical attack, extreme heat or cold, friction, extrusion or compression set.

PTFE seals have three basic design elements:

  • A pressure-actuated U-shaped jacket
  • A metal spring loading device
  • High performance polymeric seal materials

So what is a spring energized PTFE seal? It’s a spring-energized U-cup that uses a variety of jacket profiles, spring types and materials in rod and piston, face and rotary seal configurations. They are used when elastomeric seals fail to meet temperature range, chemical resistance or friction requirements.

Jacket profiles are made from PTFE and other high performance polymers. Spring types are available in corrosion-resistant alloys, including stainless steel, Elgiloy and Hastelloy.

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Kalrez Perfluoroelastomer Parts for Pharmaceutical and Food Handling Applications

Kalrez® parts made from compounds 6221 and 6230 provide superior chemical resistance and low contamination from extractables in pharmaceutical and food handling applications where FDA compliance is required. Compounds 6221 and 6230 are especially suited for Water For Injection (WFI) systems, Steam-in-Place (SIP) cleaning and other critical systems,

Unlike other elastomeric seals made with FDA compliant elastomers, Kalrez perfluoroelastomer parts are thermally stable up to 260°C (500°F), permitting use in applications such as Stage II Sterilization processes, where other elastomers lose their sealing capabilities.

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Reduce Fuel Consumption and CO2 Emissions with the Low Friction Simmerring

Low Friction SimmerringFreudenberg’s Simmerrings seal rotating shafts reliably and are used in millions of applications and with a variety of equipment in general industry and the automotive sector.

This radial shaft seal ring is based on know-how gained from years of experience. It continually undergoes further refinement based on the latest technological developments, and is particularly functionally reliable, flexible and extremely stressable.

Always “up-to-date”
The tried-and-tested original Simmerring keeps up with the times. Freudenberg’s experts have continued to develop it, with improvements in seal lip profiles. This has made it possible to further enhance its reliability and functionality across a broad range of applications. The advances include a friction-optimized design – the Low Friction Simmerring® – to decrease fuel consumption, which leads to reductions in CO2 emissions.

Gallagher Fluid Seals offers a comprehensive selection of Freudenberg Sealing Technologies products suited to a variety of requirements.

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Drop-in-Place Seals

Drop-in-place seals offer easy installation and time-savingdrop-in-place seals assembly, providing seal retention in straight-wall or dovetail grooves.

Gallagher and the Parker ISS Division design each drop-in-place seal with the application in mind, taking into consideration the material and manufacturing process of the mating surfaces to determine the most efficient design.

The drop-in-place design utilizes a rubber encapsulated plastic or metal backbone, lined with retention and stabilizer ribs. This design holds simple or complex seal shapes, easing installation and providing automation possibilities. Small contact points require less flange loading, providing maximum sealing under minimal pressure for non-ideal surfaces.

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