Category Archives: O-rings

Read more about O-ring seals in this collection of articles, which covers a variety of topics related to O-ring sizes and size standards, seal materials, installation, and much more.

Reduce Downtime and Costly Seal Replacements: Seal Failure Diagnosis Part 2

Article re-posted with permission from Parker Hannifin Sealing & Shielding Team.

Original content can be found on Parker’s Website and was written by William Pomeroy, applications engineer, Parker O-Ring & Engineered Seals Division.


As mentioned in part one of Parker’s seal failure blog series, O-ring and seal failures are often due to a combination of failure modes, making root cause difficult to uncover. It’s important to gather hardware information, how the seal is installed, application conditions, and how long a seal was in service before starting the failure analysis process. In part 1, compression set, extrusion and nibbling, and spiral failure were discussed. In part 2 of Parker’s series, they will review four other common failure modes to familiarize yourself with before diagnosing a potential seal failure in your application.

Rapid gas decompressionRapid Gas Decompression

Rapid gas decompression (commonly called RGD, or sometimes explosive decompression (ED)) is a failure mode that is the result of gas that has permeated into a seal that quickly exits the seal cross section, causing damage.

Detection of this failure mode can be difficult, as the damage does not always show on the exterior.  When the damage is visible, it can look like air bubbles on out the outside, or perhaps a fissure that has propagated to the surface.  The damage may also be hidden under the surface.  If the seal is cut for a cross section inspection, RGD damage will look like fissures in the seal that may or may not propagate all the way to the surface.

Parker’s guidance as to how to avoid this failure mode is: 1) Keep the depressurization rate lower than 200 psi per minute.  If this cannot be achieved, they would suggest 2) RGD resistant materials.  Parker offers these RGD resistant options from the HNBR, FKM, EPDM, and FFKM polymer families.

AbrasionAbrasion

Abrasion damage is the result of the seal rubbing against a bore or shaft, resulting in a reduction of cross sectional thickness due to wear.  As the seal wears, it has the potential to lose compression on the mating surface.  This wear is compounded by the fact that dynamic applications already have lower compression recommendations.

To reduce risk for this failure mode, it requires consideration during design and seal selection.  The surface finish and concentricity of the hardware will be very important considerations.  A smooth surface results in less friction (suggest 8 to 16 RMS), which in turn results in less wear.  Increasing the durometer of the seal material helps resist wear, and there are also internally lubricated materials that could be employed.  If the application is high temperature, one should consider the impacts of thermal expansion on the elastomer being used.  The thermal expansion increases contact pressure, which would increase friction / wear. Continue reading Reduce Downtime and Costly Seal Replacements: Seal Failure Diagnosis Part 2

The Advantages and Disadvantages of the Channel Seal

The Channel Seal (or Cap Seal, as it’s often referred to), was one of the earliest forms of Polymer or Teflon sealing in the seal industry.

The product is easily applied. It didn’t replace the O-ring, but instead offered improved life while reducing drag.

In doing so, hydraulic and pneumatic systems operated cooler and quieter, while improving overall performance of the product.

picture of channel seal

Evolution of the Channel Seal

Before the Channel Seal, the Backup ring was established. The first Backup rings started out as leather, as this material was readily available and could be easily formed into any shape with simple dies to stamp the Backup ring out.

Back up rings provided support for the O-ring, allowing the O-ring to operate at higher pressures, while closing off the Extrusion or “E” gap. This stopped the O-ring from being nibbled in the extrusion gap, therefore extending the life of the O-ring.

Teflon Backup rings were a big improvement, as they would better fill the gap and would stay put (as opposed to leather, which tended to shift in the groove). With the use of two Backup rings, an O-ring was well supported from pressure in both directions.

It was a simple matter to connect the two Backup rings with a thin membrane of Teflon, which removed the O-ring from the sealing surface. This change reduced drag and improved performance, while still maintaining an excellent mechanism for extrusion resistance.

This design was relatively simple to machine out of Teflon, but installation was a challenge, as the Backup rings were full depth. This caused the seal to become distorted during the install process. Today, we almost never see this type of design.

With CNC machining, the ability to nestle, and an O-ring design in a complex Teflon shape, it gave rise to what is referred to today as the Channel Seal, or Cap Seal.

This style seal offers an abundance of advantages over standard back-up rings and the early version of the Channel Seal, which was simply a Backup ring with the membrane of Teflon in-between. Continue reading The Advantages and Disadvantages of the Channel Seal

Sealing Solutions for Large Diameter Rotating Shafts: ZAVA V-Rings

First, What is a V-Ring?

The function of a V-Ring seal, or V-Ring, is to act as a centrifugal seal acting against the bearing face, pushing dirt and contaminants away from the bearing area.  V-Rings are not designed to seal against fluids or pressure differentials. However, as stated above, they are excellent at excluding all sorts of contaminants. They provide effective protection against loss and maintenance, reduce wear, increase the life of the retainer and bearings, and also work well in dry running applications.

V-Ring Applications

picture of zava seal v-ring
The most innovative V-Ring on the market: The Zava Seal with a quick-lock mechanism.

V-Rings are suitable for a whole range of sealing applications as well as rotary shaft applications such as electric motors, pumps, and agricultural machinery. This type of seal has proved to be reliable and effective against penetrating impurities such as dirt, sand, dust, greases, and splashes of water & oil in a variety of industries:

  • Pulp and paper
  • Steel mills
  • Cement mills
  • Mining
  • Rolling mills
  • Power generation
  • Fluid power
  • Chemicals
  • Food & Drink

How Do V-Rings Work?

V-Rings are flexible rubber seals that work by stretching and fitting onto a shaft and then rotating with the shaft against a counter face. They are designed to give the lips an automatic sealing action. They help to increase the sealing area by providing secondary sealing as pressure acting on the platform ring.

The Split V-Ring with ZAVA Quick-Lock

The V-Ring from ZAVA® Seal has a unique patented quick-lock that can be assembled quickly and easily, and in some cases can be installed without shutting down the filter. Because it’s mounted without vulcanizing, machinery downtime is significantly reduced. When “snapped in place,” the locking technology makes it impossible to detach. The quick-lock mechanism is made of acid-proof steel (SS 2343).  The split V-Ring from Zava can be made in many different lengths and cross sections and also in several different types of materials, specifications, and profiles.

Advantages of the Split V-Ring With ZAVA Quick-Lock

  1. Split and lockable
  2. Fast and easy to assemble
  3. Unique and patented quick-lock
  4. Elastic and workable
  5. Reduction in fiber loss
  6. Maximum leakage reduction
  7. No wear of the shaft
  8. A variety of different sizes

How Does the Quick-Lock Work?


For more information about the Zava Seal and to see if it might be the right fit for your application, contact Gallagher’s Engineering Department today.

Gallagher Fluid Seals is an authorized distributor of Zava Seal.

Installation of Linear Fluid Power Seals

Article re-posted with permission from Parker Hannifin Sealing & Shielding Team.

Original content can be found on Parker’s Website and was written by Nathan Wells, application engineer, Engineered Polymer Systems Division.


So, you’ve unboxed the shiny new Parker seals you ordered – now what?  Installing seals for the first time can be challenging without the right know-how and tools. In this article we’ll discuss best practices for seal installation in linear fluid power systems, and how to design your system to make seal installation fast and damage-free.

SEAL GROOVE STYLES

picture of closed rod seal groove

First, let’s look at three common groove styles:

•    Closed
•    Stepped, and
•    Open (or two-piece)

Closed groove

The closed seal groove fully encapsulates the seal and is the most common style used (see Figure 1).

Closed grooves are simple to machine and offer the best support for seals. Since seals in this configuration are surrounded by solid metal, without a well-developed process, installation can be challenging. Rod seals need to be folded to fit into internal (throat) grooves and piston seals must be stretched over the outside of the piston.

picture of cylinder head and piston seals

Notice how both designs shown in Fig. 2 and Fig. 3 utilize static seals (turquoise colored seal) on the opposing side of the dynamic, primary seals. Therefore, installation in either instance requires techniques and tools for both rod and piston seals.

Stepped groove

Typically utilized to ease seal installation, stepped grooves feature a reduced diameter on the low-pressure side of the seal as shown in Fig. 4 and Fig. 5.

picture of rod stepped groove

As shown, the “step” is just wide enough to hold the seal in place as the rod or piston strokes back and forth. This way, seals don’t have to be folded or stretched nearly as much when installing. This design works well for single seals only holding pressure from one direction, like Parker FlexiSeals™.

When using multiple seals stacked in series or in systems with bi-directional pressure, a closed or two-piece groove is needed for support on both sides.

Open and two-piece grooves

Open or two-piece grooves are used when the seal is either too small to be stretched or folded into a closed groove, or if it’s made of a material that doesn’t spring back after flexing.

Figures 6 and 7 show two examples of open grooves. Figure 6 uses a washer and a snap ring to hold the seal in place. Figure 7 uses a bolt-on cap. These groove designs can be used for bi-directional seals, too. As you can see, open grooves cost more to produce but seal installation is a snap.

picture of open rod groove

Open grooves also make removing the seal much easier – useful in systems which require periodic seal replacement. Continue reading Installation of Linear Fluid Power Seals

Reduce Downtime and Costly Seal Replacements: Seal Failure Diagnosis Part 1

Article re-posted with permission from Parker Hannifin Sealing & Shielding Team.

Original content can be found on Parker’s Website and was written by William Pomeroy, applications engineer, Parker O-Ring & Engineered Seals Division.


There are many situations where an O-Ring may not last as long as one thinks that it should. When the expectation is realistic and yet the seal fails earlier than expected, Applications Engineering teams are often asked to help discover the seal failure mode(s).

Seal failure is often due to a combination of failure modes, making root cause difficult to uncover. When beginning a failure analysis, items usually asked for include: hardware information, how the seal is installed, application conditions (temp, fluids, and pressure exposure), and how long into the service that the seal failed. These details help bring the overall application into focus and enable a quick diagnosis to help resolve seal failures. In part one of the seal failure blog series, we will discuss compression set, extrusion, and spiral failure.

Compression set

  • picture of compression setCompression set is likely the most common failure mode for elastomer seals. Compression can be defined, or rather quantified, by the seals ability to return to its original shape after compression is removed. Zero percent compression set indicates that no relaxation (permanent deformation) has occurred, while 100% compression set indicates that total relaxation (seal no longer applies a force on the mating surface). When investigating material options, note that the lower the % compression set for a given compound, the more resilient the material is. However, it is extremely important to ensure you are making equal comparison in terms of time and temperature for the test conditions.
  • There are many potential causes for compression set.
    • Poor material properties
    • Improper gland
    • Fluid incompatibility
    • Temperature exposures above the recommended range for the material.

Extrusion and Nibbling

  • picture of extrusionThe driving force (pun intended) for this failure mode is the pressure load that the seal is exposed to. Extrusion most often occurs when a seal material deforms into the space between the bore and the outside of the tube (commonly referred to as the extrusion gap or “E-gap”). An approximation for the pressure rating for a seal can be determine by evaluating figure 3-2 of the Parker O-Ring handbook. The X-axis shows the size of the clearance gap (total gap, or diametral gap), and the Y-axis is the pressure load. The curves on the chart correspond to the hardness of the rubber. Extrusion can also occur due to gland overfill, when the deformation from compression of the seal fills the entire groove and lips over into the extrusion gap.
  • Face seals do not usually have an extrusion gap, so this orientation can achieve much higher pressure loads than a radial seal. Without a gap for the seal to extrude into, the risk of significant extrusion is highly diminished.
  • Extrusion in radial seals can by combated by reducing the clearance gap or by adding a back up ring.

Spiral Failure

  • picture of spiral failureSpiral failure can be more simply described as the O-Ring rolling in the groove. This failure more is most common in dynamic reciprocating O-Ring applications. However, spiral failure can also occur during installation. An image of spiral failure is unique, and relatively easy to diagnose, but the root cause of spiral failure can sometimes be difficult to pinpoint. Uneven surface finish, poor lubrication, side loading, eccentricity, or perhaps stroke speed can all contribute to spiral failure.

Check out Parker’s neat video about Seal Failure Modes:

Parker and Gallagher Fluid Seals can help diagnose seal failures and the best sealing solutions for your application.

Stay tuned for Part 2 in this series.


For more information about how Gallagher Fluid Seals can help you, contact our engineering department today.

Metal Detectable & X-Ray Detectable Rubber Materials

Food, Beverage, and Pharmaceutical Regulations

picture of metal detectable o-ringStringent government regulations mandate that food, beverage, and pharmaceutical manufacturers keep foreign material out of ingredients to ensure food and drug safety for consumers. Preventing foreign material from entering the processing stream is of the utmost concern but there must also be measures in place to detect contaminated product and quarantine it before distribution.

Component parts that are used in food and drug processing equipment can become damaged by improper installation and/or excessive shear experienced during operation that causes fragments of rubber, plastic, and metal to contaminate ingredients. Chemicals used for cleaning and sterilization of equipment can cause rubber seals to degrade, increasing the probability of particles breaking off and entering the consumable products. Part failures causing product contamination can lead to machine down time, scrap product, product recalls and result in legal problems and negative media attention. All of which have a significant financial impact and can compromise brand loyalty within the market.

Hazard Analysis Critical Control Point (HACCP)

picture of precision metal detectable o-ringsMany processing operations now employ HACCP (Hazard Analysis Critical Control Point) programs which stipulate that all parts have to be metal detectable and X-ray detectable. This made it necessary to develop special rubber materials that would allow food processors to conduct routine inspections for this type of contamination utilizing in-line metal detectors and X-ray machines. Rubber must be compounded with special additives to make detection possible. However, certain foods have phase angles similar to metal detectable rubber so a complete understanding of the rubber product’s application is necessary for proper compound selection.

Metal Detectable O-Rings | X-Ray Detectable O-Rings

Precision Associates has developed four Metal and X-Ray detectable materials made with ingredients sanctioned under FDA Title 21 CFR 177.2600.

All four materials are 3A Sanitary 18-03 approved and are available in Silicone, Nitrile, EPDM, and FKM. Each is 70 durometer and blue in color. (The industry standard color is blue but materials can be colored for specific customer requirements and any polymer can be made metal detectable).

All compounds were tested by an independent laboratory and found to have magnetic properties that exceed industry standards.

picture of compound table precision o-rings


The original article was written by Precision Associates, Inc. and can be found here.

For more information about what Gallagher can offer through Precision Associates, or to talk to a technical sales expert about these materials, contact us today.

How to Solve Large-Size Sealing Challenges at Temperatures up to 800°C (1472°F)

Article re-posted with permission from Parker Hannifin Sealing & Shielding Team.

Original content can be found on Parker’s Website and was written by Thorsten Kleinert, Business Unit Manager, Composite Sealing Systems Engineered Materials Group, Europe.


When classic sealing materials reach their limits, such as temperature ranges above 300°C and below -50°C – alternative materials are sometimes required, such as metal seals with appropriate coating/plating.

picture of metal sealParker offers metal seals made of stainless steel or nickel alloys in C-rings, E-rings, and other o-ring designs characterized by high pre-loading force and significant resilience. Drawing on many years of experience in the gas turbine market, Parker has continually expanded its expertise in large diameters and developed special problem solutions that substantially increase the efficiency of the machines.

Metal Seal Types and Sizes

The most important manufacturing technologies used to produce metal seals from stainless steel or nickel alloys are rolling, forming, CNC machining, welding, heat treatment, and coating/plating. In its more than 60-year history of producing metal seals, Parker has continually tackled the challenge of manufacturing increasingly large metal seals. Currently, spring-energized C-rings with a diameter of up to 7.6 m can be produced for which special forming machines and patented welding techniques were developed. They are supported by optimized special heat treatment and electroplating processes that make it possible to manufacture high-quality products even in such large dimensions. Additionally, Parker offers non-rotationally symmetric metal seals. These E-, O- and C-seals can be produced in lengths of up to 2.3 m on machines specifically developed for this purpose.

Products

  • C-seals: ≤ 3,000 mm (118 inches)
  • Spring-energized C-seals: ≤ 7,600 mm (299 inches)
  • O-rings: ≤ 1,200 mm (47 inches)
  • E-seals:
    • Heat-treated ≤ 2,700 mm (106 inches)
    • Segmented ≤ 7,600 mm (299 inches)

Materials and Coatings

picture of gas turbineThe base materials used are special nickel alloys that withstand temperatures of more than 800 °C. These cobalt-nickel-chromium-tungsten alloys or heat-treatable nickel super-alloys make high demands on the welding technology used and are reliably processed at Parker due to optimized manufacturing processes and comprehensive suitability tests.

The choice of plating is primarily focused on wear protection, corrosion resistance and improvement of the sealing properties. For this purpose, the surface properties of the metal seal are modified and a formable external surface layer with adjusted hardness is created.


For more information about  sealing large-size applications with high temperatures, contact Gallagher’s engineering department.

Gallagher is an authorized distributor for Parker products.

Kalrez® 7375 Offers Outstanding Properties & Performance

Kalrez 7375 offers broad chemical and water/steam resistance

The newer compound from DuPont™, Kalrez 7375, is an innovative FFKM oil-seal product exhibiting broad chemical and water/steam resistance properties required at high temperatures in chemical process industry applications. Kalrez 7375 parts present excellent compression set resistance, exceptional physical property retention, and improved mechanical strength properties. Other Kalrez compounds have done the job over the years when faced with many of these sealing challenges, but how does it compare to this new compound?

Three ways that Kalrez 7375 would be a suitable upgrade or compatible compound for your application:

1. Kalrez® 1050LF is a classic grade and longtime favorite for premium performance. 1050LF end-users will likely see a performance boost if they switched to 7375, especially if used in steam or hot water applications.

2. If using Kalrez® 4079 or Kalrez® 7075 and broad chemical resistance is essential (including water/steam), 7375 could be a superior compatibility match resulting in enhanced longevity. 7075 offers the highest thermal capability but cannot support 7375’s chemical compatibility with steam. See table below:

Volume Change between different FFKMs after 672 hours of chemical immersion.

3. If lifetime issues or seeking to extend time between repairs are concerns when using Kalrez® 6375, end-users would most likely see a significant impact with 7375. However, transitioning to 7375 is not necessary if 6375 is executing up to standards.

Kalrez 7375 Benefits

  • Superior thermal stability of 572 °F (300 °C)
  • Excellent broad chemical resistance
  • Outstanding steam and water resistance
  • Available in most O-ring sizes: AS568, Metric, JIS (custom shapes upon request)
  • Combination of Kalrez® quality and Gallagher Fluid Seals’ customer service
picture of kalrez compression graph
Kalrez 7375 demonstrates excellent long-term compression set in hot air at 500 degrees Fahrenheit.

Product Description

DuPont™ Kalrez 7375 perfluoroelastomer parts are an innovative FFKM product based on a patented crosslinking system for chemical process industry applications where broad chemical and water/steam resistance are needed at elevated temperatures. Kalrez 7375 parts exhibit excellent compression set resistance, outstanding physical property retention, and good mechanical strength properties. A maximum application temperature of 300 °C is suggested.


The original article was featured on Dichtomatik’s website and can be found here.

Gallagher Fluid Seals is an authorized distributor of Kalrez products. For information about selecting the correct compound for your specific application, contact our engineering department.

How to Properly Measure an O-Ring

Measuring an O-Ring is quite simple when you have the right tools at your disposal. All that is required is a clean, level surface; an o-ring; and a measuring device such as a caliper or other measuring tools such as cones, gauges, and size charts.

Directions to Measure an O-Ring

To measure an O-Ring, following the directions below:

  1. Place your o-ring on a flat surface clean of debris.
  2. Determine the inside diameter (ID) and outside diameter (OD) of the o-ring. The o-ring dimensions chart below illustrates where on the o-ring each dimension is measured.
  3. Measuring the width, or cross-section (CS), can be tricky and is measured by lightly pressing the caliper ends onto O-ring as shown in section A-A.

For more information on O-ring sizes click to see the JIS B 2401 Standard O-Ring Size Tables.

Dimensionally specifying an o-ring can typically be done with just two dimensions, the inner diameter (ID) and the cross-section (CS). Occasionally, an O-ring may be specified with an outer diameter (OD) and cross-section or an inner diameter and outer diameter. If two of the three dimensions are known, the third can be calculated using the formulas shown below.

O-Ring Dimensions

O-Ring Dimensions

 

O-Ring Dimension Calculations

o-ring dimension calculations


The original article can be found on Dichtomatik’s website. Gallagher Fluid Seals is a distributor of Dichtomatik, a brand of Freudenberg.

For more information about measuring o-rings or determining the best o-ring to use, please contact Gallagher’s engineering department.

Gallagher Fluid Seals Announces e-Commerce Store

Better and faster access to the seals you need to keep your production running.

King of Prussia, PA. October 29, 2019 /News and Updates/ — Gallagher Fluid Seals (GFS) is excited to announce the launch of its e-commerce store, providing a brand new experience to shop for seals.

“It’s been a complete team effort,” says Chris Gallagher, CEO. “Our team has worked diligently over the past several months to prepare and deliver a state-of-the art e-commerce store for both new and returning customers.”

As the world’s economy has evolved to an online platform, GFS felt seal buying should be easier. Gone are the days of calling in and ordering a replacement seal – or sending an RFQ. This new online experience allows greater and faster access to the seals you need to keep your facility up-and-running.

“Maximizing the ease-of-purchase and visibility of fluid sealing products is imperative to the future of seal buying, and that’s why we are well-positioned to help our customers for years to come,” says Chris.

To start, Gallagher’s e-commerce store will focus on six main product categories:

  1. O-Rings
  2. Gaskets
  3. Sheet Material
  4. Expanded PTFE
  5. Compression Packing
  6. Mechanical Seals

In the coming months, the full product array will be added to shop.gallagherseals.com, providing even more fluid sealing options. Specialty products such as expansion joints, bearings & bushings, rotary seals, and more will be added.

We’re excited about this new chapter in Gallagher Fluid Seals’ history, and we hope you will join us in this journey to make your seal shopping experience easier and more transparent.

Shop our new e-commerce website here:

>> shop.gallagherseals.com

For larger orders or custom-engineered sealing needs, it’s suggested that customers complete a form on our e-commerce website requesting to speak with an engineer or member of the customer service team.


About Gallagher Fluid Seals, Inc.

For 60+ years, Gallagher Fluid Seals has taken pride in being the industry leader for all things seals. Not only was Gallagher the first North American seal distributor to achieve ISO 9001 certification, but year-after-year, GFS takes steps to maintain its status as the leading distributor for fluid sealing products: In January 2019, Gallagher made an additional company acquisition – this time acquiring Quality Seals out of Bethel, CT. This strategic acquisition has been great for customers. It has helped to bolster capabilities and expand product lines while simultaneously opening a custom engineering channel to Quality Seals’ existing customers.

Contact:
Kevin Patton
Marketing & Communications Analyst
610-277-8200