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.

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

Semiconductor Fabs Lower Cost of Ownership with HiFluor Materials

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

Original content can be found on Parker’s Website and was written by Nathaniel Reis, Applications Engineer for Parker O-Ring & Engineered Seals Division.


parker hifluor processIn our semiconductor entry from last month, we noted that lowering the cost of ownership is a multi-faceted goal. We discussed how one of the areas for potential improvement is mechanical design and how the Parker EZ-Lok seal is a major solution to mechanical seal failure. In this entry, we’ll investigate a notably different type of cost-reduction opportunity – material selection – and see how Parker’s innovative HiFluor compounds can reduce seal costs to as little as half.

Critical Environments

When it comes to the seal industry, the semiconductor market is well known as one where the most premium, chemical-resistant compounds are a necessity. Microelectronic manufacturing processes involve chemistries that push the limits of what elastomeric compounds can withstand in terms of both chemical aggressiveness and variety. The perfluorinated materials (FFKM) capable of withstanding these environments require intricate manufacturing processes regulated by closely-guarded trade secrets and the significant investment of resources.

These factors drive the price of FFKM compounds to the point of being as much as 50 times the cost of any other variety. Cutting just a slice out of this cost can result in significant savings – a chance to take out a quarter or even half the pie would be advantageous to the overall bottom line. Fabricators should be continually on the lookout for more cost-effective compounds that show equal performance in their pertinent operations.

hifluor compound pictureThis is why Parker’s HiFluor compounds offer an opportunity for cost savings that shouldn’t go unnoticed. A unique hybrid of performance between FFKM and the simpler technology of fluorocarbon (FKM) elastomers, HiFluor offers the most superb chemical compatibility in the many semiconductor environments where the high temperature ratings of FFKM aren’t necessary – and at a fraction of the cost.

Not only can HiFluor be used where even FKM is lacking, but its performance in applications with aggressive plasma exposure is spectacular as well. This can be observed by its overall resistance to plasma-induced material degradation. However, Parker has also developed multiple formulations that display extremely low particle generation when most materials would be expected to suffer severe physical and chemical etch.

Solutions and Cost Savings

As an example: One major semiconductor fab had several factors (other than their seals) dictating the frequency of their preventative maintenance (PM) intervals. The fab wanted to replace their seals at these intervals as a precautionary measure to limit the chance of them becoming another PM-increasing factor. However, this caused these premium FFKM seals to be a source of inflated cost. Parker assisted with a process evaluation that resulted in over half the seals being replaced with cost-effective HiFluor O-rings, while the tool regions with more intense plasma exposure were reserved for the elite performance of Parker’s FF302.

Another major fab in the microelectronics industry switched from FKM to FFKM seals in their oxide etch process. The tool owner achieved the desired performance improvement, but soon began searching for less expensive options. The owner recognized the plasma resistance and low particulate generation of Parker’s HiFluor compound, HF355. After implementing this change, he retained the performance improvement, but at a fraction of the cost.

Semiconductor tool owners understand that their aggressive processes require the most robust, expensive FFKM seal materials. The price tag on these seals is greater than those from any other compound family. Fortunately, HiFluor is a proven sealing solution that can bridge the gap and provide the same kind of high performance at a much lower cost.


For more information about Parker O-Rings, including HiFluor, or to find a custom solutions for your application, contact Gallagher Fluid Seals today.

Semiconductor Fab Processes Benefit From Retention Ribbed EZ-Lok 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 Nathaniel Reis, applications engineer, Parker O-Ring & Engineered Seals Division.


When it comes to semiconductor fabrication processes, reducing the cost of ownership is a multi-faceted goal approached from a variety of angles. Tool engineers and equipment technicians take pride in their ability to identify factors that limit tool uptime. One constant headache they face is the mechanical failure of seals in dynamic environments. This can lead to premature downtime or reduced preventative maintenance (PM) intervals, both of which lead to a higher cost of ownership. Fortunately, tool owners have begun to implement seal designs better suited for these dynamic environments: Parker EZ-Lok is a proven solution.

Spiral Failure

picture of spiral o-ring failure

One of the more extreme forms of mechanical failure to be prevented is twisting and spiraling of an O-ring during operation. This occurs with O-rings in dovetail glands where one of the sealing surfaces is a door that opens and closes against the seal. The combination of stiction to the door and stretch in the gland causes the O-ring to roll and twist repeatedly with each cycle, resulting in permanent cyclic deformation. This means that a seal profile with a flat contact surface is vital for this type of dynamic function.

Other designs

The basic D-profile is the fundamental simple shape that serves as the basis of the EZ-Lok solution. The flat portion of the “D” holds the seal in place and prevents rolling, while the opposite, round contact surface focuses the sealing force and helps keep volume requirements at a minimum. These geometric features make for sound sealing function while preventing the drastic spiral damage seen so often in the industry.

picture of d-profile

A standard D-ring is still more limited by volume requirements than traditional seals like O-rings. In addition, a D-ring’s sharp corners can become difficult to install past the top groove radii if the seal is made much wider than the groove opening. On the other hand, a seal made any narrower would be easily removed without intention, such as that induced by stiction to the door. These reasons are why the basic D-profile alone is not the answer to these failure modes.

The Solution

picture of Parker EZ-Lok seal

The solution to these dilemmas is a unique D-shaped profile with a geometry that lends itself to the spacial constrictions of dovetail glands, prevents rolling, and locks into place: the Parker EZ-Lok seal. These seals are designed with special retention ribs placed with precise frequency around the seal circumference that allows for smooth installation and keeps the seal retained in the gland. This design also removes any tendency to stretch the seal during installation, which is often seen with more conventional seals.

The combination of retention ribs with a fundamental D-ring profile makes EZ-Lok the ideal geometry for effective use of the high-performance compounds typically required for aggressive semiconductor chemistries. EZ-Lok seals allow for lower cost of ownership through PM-minimization and reduced seal overhead costs, made possible by effective mechanical design. This is an example of how Parker’s effective design engineering can reduce the cost of ownership and bring premier solutions to the table.


For more information about Parker’s full suite of solutions and sealing products, contact Gallagher Fluid Seals’ engineering department.

Freudenberg Announces New VMQ Materials

When it comes to food, Freudenberg wants to be sure that its sealing materials are free of harmful substances.

In the food processing industry, in order to guarantee food safety, both the food and the hardware that come into contact with it must meet particularly stringent criteria. These guidelines also apply to sealing materials.

picture of food processing plantIn China, specific standards were created in 2016 with the two standards GB 4806 and GB 9685, which deviate from the existing relevant American and European regulations for food-grade materials. To meet the stringent Chinese regulations, FST has now successfully tested two proven VMQ materials: 70 VMQ 117055 and 60 VMQ 117117 for their conformity with Chinese guidelines.

The Chinese standard GB 9685 specifies which ingredients may contain materials that come into contact with food in a so-called positive list. A large number of seal-relevant ingredients that conform to 21 CFR 177.2600 of FDA (U.S. Food & Drug Administration) and European EU (Reg.) 1935/2004 are not listed here. This applies to elastomers. For a global food release, new material compositions must therefore be developed or proven materials tested for their conformity with the specifications.

Global food approvals require extensive testing

The basic requirements for gasket materials as well as sensory tests and migration tests are defined in standard GB 4806. Two of Freudenberg’s newly developed EPDM materials have successfully passed the tests: 75 EPDM 386 and 85 EPDM 387. 

After extensive testing, FST’s two new VMQ materials now meet the requirements of the Chinese standards. As an example: the silicones in the migration measurement in mg/dm2 had a result of <1, and are far below the specified limit of ≤10.

In addition to the EPDM materials which are characterized by media resistance, good processing behavior and a long service life, FST’s new silicones, 70 VMQ 117055 and 60 VMQ 117117 provide grease-resistant material selection for use in contact with food in the Chinese market.


Gallagher Fluid Seals is a preferred distributor of Freudenberg sealing. For information about Fruedenberg, or if you have needs for a custom solution, contact our engineering department.

The original article or press release can be found on Freudenberg’s website.

A Short Guide for Rubber Seals & Design

Rubber seals are used in numerous industries to prevent the unwanted leakage of liquids and gases in various components such as pumps, valves, pipe fittings, and vacuum seals, to name only a few. However, all seals are not created equally. Rubber seal design consists of several elements to ensure that the seal delivers optimal performance in the given environment.

One of the most common types of industrial rubber seals, the O-ring, relies on mechanical compressive deformation to act as a barrier between mating surfaces, thus restricting the flow of fluid in predetermined areas. Several factors must, therefore, be taken into account in O-ring seal design to sustain the compressive force and maintain an effective seal.

Key Design Considerations

Rubber seals are available in a large number of material compositions, each with its own set of advantages and limitations. The selection of the appropriate material involves the consideration of specific factors including:

Dimensional Requirements

To provide a proper seal, the O-ring needs to be compressed between the mating surfaces. The deformation caused by this compression is what prevents fluid leakage. To achieve the proper compressive force and deformation, the cross section of the O-ring needs to be sufficiently larger than the gland depth.

As the two mating surfaces press together, the O-ring seal compresses axially and exerts an equal and opposite force at the top and bottom ends of the seal. If the O-ring is too small, the seal may not compress when the surface come together. On the other hand, an O-ring that is too large will over pack the gland and disrupt the connection between the mating surfaces.

Friction

Friction considerations are essential in dynamic applications – in situations that involve relative movement between the mating surfaces.

In reciprocating applications, these movements can generate frictional forces which may cause failure due to abrasion or extrusion and successive nibbling of the seal. In rotary applications, friction may generate excessive heat and seal expansion due to the Joule effect. In both of these applications, proper groove design, along with appropriate lubrication and speed of operation can help to avoid these issues. Silicone and related materials such as Fluorosilicone, liquid silicone rubber, and medical grade silicone are often avoided in dynamic applications due to their low abrasion/tear resistance.

temperature considerationTemperature

Long-term exposure to excessive heat can cause inappropriate rubber seals materials to deteriorate physically or chemically over time. Excessively high temperatures can cause specific materials to swell and harden, resulting in permanent deformation. Conversely, overly cold temperatures may cause material shrinkage and result in leakage due to loss of seal contact, or insufficient compressive force due to stiffening of the rubber compound.

Therefore, the appropriate seal material should be selected to withstand the expected temperature ranges of the environment. The length of exposure should also be considered. For example, would the temperatures be sustained in short intervals or at sustained levels?

Pressure

Differential pressures tend to push rubber seals (o-rings) to the low-pressure side of the gland causing it to distort against the gland wall. This action blocks the diametrical gap between the mating surfaces and results in the formation of a positive seal. Excessively high pressures can cause softer O-ring materials to extrude into the diametrical gap resulting in permanent seal failure and subsequent leakage. To avoid this situation, seal materials that operate optimally within the expected temperature range should be selected.

chemical compatibilityChemical Compatibility

One of the most critical considerations for rubber seals design and material selection is determining the material’s resistance to exposure to specific chemicals. Some fluids can react negatively with certain materials while having little to no effect on another. For example, Nitrile is highly resistant to petroleum-based oils and fuels, while the use of Butyl is avoided in applications with exposure to petroleum and other hydrocarbon-based solvents due to its poor resistance.

Remember to keep dimensional requirements, friction, temperature, pressure, and chemical compatibility in mind when it comes to customizing a rubber seal solution for your application.


For more information about custom seal designs or to see which seal might be the best fit for your application, contact Gallagher Fluid Seals.

The original article can be found on Precision Associates website, and was written in January 2019.

Degradable Materials Simplify Well Completions in Oil & Gas Extraction

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

Original content can be found on Parker’s Website and was written by members of the O-Ring & Engineered Seals Division. Jacob Ballard – research and development engineer, Jason Fairbanks – market manager, and Nathaniel Sowder – business development engineer.


degradable materials for offshore drillingThe emergence of degradable and dissolvable materials is providing oilfield service companies an opportunity to increase efficiencies and cut costs in the oilfield by simplifying well completions. These materials replace their conventional metallic and polymeric counterparts in completion tools, but eventually break down and disperse when exposed to common completion fluids. This eliminates the need for well interventions to mill out or retrieve used tools. This can result in a reduction of drill time, a safer work environment, and monetary savings for the operator. Parker Hannifin produces dissolvable and degradable metal alloys, thermoplastics, and elastomeric materials that can enhance your well completions.

Degradable Elastomers

Parker O-Ring and Engineered Seals (OES) Division produces degradable elastomer formulations that can be used in frac plugs, liner wipers, and other sealing applications common in the completions segment. These elastomer formulas have tough physical properties and low compression set and are designed to replace materials such as Nitrile or HNBR in conventional tool designs. With proper design, tools using Parker degradable elastomer can withstand the high pressures (>8,000 psi) generated during hydraulic fracturing while still eventually deteriorating away, allowing well production without having to be drilled out. These degradable elastomers can be produced in a variety of desired forms such as O-rings, custom molded shapes, and packing elements. They can also be bonded to dissolvable metal alloys to produce completely degradable solutions. If needed, Parker offers a product engineering team to assist with the design of components and rapid prototyping services to help cut down on development timelines.

Degradable Thermoplastics

Parker Engineered Polymer Systems (EPS) Division manufactures engineered degradable Thermoplastic materials which can be used in many types of completion tools that traditionally use non-degradable elastomers. Parker EPS’s high-grade thermoplastic materials have increased physical properties over conventional elastomers making it ideal for both high pressure/high temperature and wear resistant applications. The increased physical properties of EPS thermoplastics provide enhanced resistance to extrusion, temperature and wear over most degradable non-metallics in the market. These unique thermoplastic materials may be manufactured in both homogenous as well as bonded components such as Packers, Parker back-up rings, Frac Plugs and liner wipers and are ideal for hot trouble well applications.

With a wide range of wellbore temperatures and completion fluids seen across the industry, selecting the right degradable compound can be complicated. Gallagher Fluid Seals, in coordination with Parker, can help assist in recommending the proper paramaters for using degradable elastomers.


Gallagher Fluid Seals is an authorized distributor of Parker. To learn more about how Gallagher Fluid Seals can help you, contact our engineering department at 1-800-822-4063

A Closer Look at Parco’s 4200 Nitrile Seals

Nitrile (NBR) is a copolymer of butadiene and acrylonitrile. Due to its excellent resistance to petroleum products and its ability to be compounded for service over a temperature range of -30°F to +250°F, Nitrile /NBR is the most widely used elastomer in the seal industry today. NBR o-rings are very versatile, inexpensive material which contributes to its wide array of applications.

Let’s start with the 4200-70 General-Purpose Nitrile Seal. What differentiates this material?

1. Excellent Physical Properties

Parco’s 4200-70 70-durometer nitrile O-rings have excellent physical properties. For nearly 40 years, 4200-70 O-rings have been used in a wide variety of  applications with great results. So when you specify 4200-70, rest assured that you’ve made the right choice.

2. Excellent Resistance to Compression Set

To perform properly, seals must resist taking a set from compression after being installed. When a seal takes a set, it no longer exerts force on the mating surfaces, resulting in leakage. A compound with low compression set, like 4200-70, better maintains its elastomeric properties and original thickness, preserving seal integrity. Seals made from Parco’s 4200-70 compound provide excellent resistance to compression set. After testing 4200-70 for 22 hours at 212°F, it had a compression set of only 6 percent.

Compression Set of a Typical Parker 70-Duro Compound

3. Very Good Resistance to a Variety of Fluids

NBR O-ring compounds, like 4200-70, provide very good service in gasoline, crude oil, power steering fluid, hexane, toluene, water, water-based hydraulic fluids, and dilute bases such as sodium hydroxide.

So, what’s the chemical resistance of 4200-70?

  • Automatic Transmission Fluid
  • Crude Oil
  • Gasoline
  • Propane
  • Water

More than 50 percent of sealing needs can be met using nitrile. Its versatile nature might be right for your application and you don’t even know it. Consider NBR before opting for something more complex!


About Parco

Founded in 1941, Parco was the first manufacturer to specialize in O-rings, still one of its primary products. Today, Parco has four modern facilities manufacturing O-rings, custom-molded elastomeric seals, rubber-to-metal bonded parts, and machined metal parts. Their 154,000 square-foot facility in Ontario, California is one of the largest plants in the world making molded rubber seals. The three other facilities in Texas and Louisiana specialize in complex custom-molded elastomeric products, machined metal parts, and machined plastics.


The datasheet for Parco’s 4200-70 can be found by clicking here.

Gallagher Fluid Seals is an authorized distributor for Parco. For more information, contact our engineering department.

Parker’s EM163-80 Meets Both NAS1613 Revision 2 and 6, Is There a Difference?

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

Original content can be found on Parker’s Website and was written by Dorothy Kern, applications engineering manager for the Parker O-Ring & Engineered Seals Division.


Perhaps you know Parker’s newest EPDM material is EM163-80. Featuring breakthrough low temperature functionality, resistance to all commercially available phosphate ester fluids, and the ability to be made into custom shapes, extrusions, and spliced geometries, EM163-80 represents the best-in-class material for applications needing to seal phosphate-ester-based fluids. The latest news is that EM163-80 meets the full qualification requirements of both NAS1613 Revision 6 (code A) and the legacy Revision 2 (no code). Parker has been inundated with questions about the specification differences between Revision 6 and 2, enough that it makes sense to devote a blog topic explaining the fluids, conditions, and dynamic cycling requirements which are required to qualify EM163-80 to each specification.

The easiest part of this comparison is evaluating the areas of Revision 6 which are very much a copy and paste from Revision 2. Compression set conditions, aged and un-aged, plus temperature retraction requirements, aged and un-aged, are identical. Lastly, both specifications require a test to verify the elastomers will not corrode or adhere to five different metal substrate materials. That is pretty much where the similarities end.  Now for the contrasts.

Specimen size

The first subtle difference is the specimen size. Both specs require testing to measure the change in physical properties and volume following a heated immersion in phosphate ester fluids. For the most part, No Code qualification requires testing to be completed on test slabs or O-rings, while the newer revision, Code A, requires testing on test slabs AND O-rings. Not a big difference, but still, a difference.

The fluid conditions are very similar in both specs, but not identical. There are only two temperatures for the short term 70 hour exposure: 160°F and 250°F. Another similarity is that the longer soaks are at 225°F for 334 and 670 hours. The more difficult A Code also requires 1000 and 1440 hours at 225°F. We begin to see the requirements for the later revision are more reflective of the industry conditions, right?

Fluids

Next, we look at the fluids, which truly are a key difference between the two documents. Revision 2 fluid is exclusively for AS1241 Type IV, CL 2 while revision 6 states the elastomers must meet “all commercially available AS1241 Type IV, Class 1 and 2, and Type V”. Table 1 outlines the AS1241 fluids in context of both NAS 1613 revisions.

Revision 2 Revision 6
Low Density Hyject IV A Plus AS 1241 Type IV class 1 X
Low Density Skydrol LD4 AS 1241 Type IV class 1 X
High Density Skydrol 500B-4 AS 1241 Type IV class 2 X X
Low Density Skydrol V AS 1241 Type V X
Low Density Hyjet V AS 1241 Type V X
Low Density Skydrol PE-5 AS 1241 Type V X

Basically, to pass Revision 6, the material must demonstrate compatibility for all six commercially available fluids, while Revision 2 only has one fluid which is must be verified for compatibility. Again, we see Revision 6 is much more comprehensive than Revision 2.

Endurance Testing

picture of o-ringsLast, we look at the functional testing of the materials, referred to as dynamic or endurance testing. Both specifications require endurance testing on a pair of seals, which have been aged for a week at 225°F. The appropriate fluids are outlined in the table above.

Revision 2 has a gland design per Mil-G-5514. There is a 4” stroke length and the rod must travel 30 full cycles each minute. The rod is chromium plated with a surface finish between 16-32 microinches. PTFE anti-extrusion back up rings are necessary for the 3000 psi high pressure cycling. A temperature of 160°F is maintained for 70,000 strokes and then increased to 225°F for an additional 90,000 strokes.

Revision 6 has a much more demanding endurance test with fives phases and slightly different hardware. The rod must be a smooth 8 to 16 microinches Ra with a cross-hatched finish by lapping, and the cycle is 30 complete strokes per minute but only 3” rather than 4”, which means the speed can be more conservative. A pair of conditioned seals are placed in AS4716 grooves, adjacent to a PTFE back up ring. Similarities to Rev 2 are that there is a pressure of 3000 psi for the dynamic cycling at both 160°F and 225°F, however before and after each high temperature cycle there is a low temperature, -65°F soak. The first soak is static for 24 hours, followed by the 160°F high pressure cycling. The second low temperature soak requires 10 dynamic cycles at ambient pressure followed by 10 cycles at 3000 psi. The final low temperature soak requires one hour static sealing at 3000 psi followed by an 18 hour warm down period.

If you read carefully through the tests, you begin to see the Revision 6 seals must go through a more rigorous test with harsh low temperature, low pressure conditions. However, Revision 2 is not without its own challenges. The required hardware configuration; ie, low squeeze and more rough surface finish, is far from optimum and not what we recommend in actual service conditions. Added to the difficulty is the longer stroke length and faster speed. The fact that EM163-80 has passed both specifications proves it is the next generation EPDM seal material ready for flight.


Gallagher Fluid Seals is an authorized distributor of Parker. To learn more about how Gallagher Fluid Seals can help you, contact our engineering department at 1-800-822-4063