Technology advancements and new to world discoveries are constantly creating a new series of challenges for seal materials in the Oil and Gas industry. In today’s environments, seals are being pushed to perform in temperature, pressure and chemical extremes never before thought to be obtainable with rubber products. Application pressures exceeding 20,000 psi, service temperatures ranging from -40°F to upwards of 500°F and exposure to some of the most aggressive media on the planet are placing immense amounts of stress on sealing elements. Parker’s FF400-80 compound has been formulated to provide a solution to all of these sealing challenges.

• Temperature range: -40° to 527°F

• Best-in-Class low-temperature FFKM

• Excellent compression set resistance

• RGD resistant per ISO 23936-2 and TOTAL GS EP PVV 142

• Sour service H2S resistant per ISO 23936-2

• Maintained resilience at high pressures and low temperatures

• Great for use in HTHP applications

An Achilles heel of perfluoroelastomer (FFKM) compounds has long been lack of low-temperature flexibility and resilience. In a sealing application, the ability for a material to push back on the mating hardware is called resilience and is very important to prevent a leak. A method of measuring a rubber compound's low-temperature resilience is by performing a temperature of retraction test per ASTM D1329. See Parker’s O-Ring eHandbook for more information on low-temperature effects. Parker’s FF400 compound has a best in class TR-10 temperature of -23°F (-31°C). This property gives FF400 the low-temperature performance never seen before from an FFKM compound. The FF400 offers low temperature sealing capability approximately 45°F below a standard FFKM compound and has an overall recommended service temperature range of -40°F to 527°F. This low-temperature capability can be extremely valuable for surface equipment such as valves but can also give an advantage in high-pressure applications where the glass transition temperature can shift causing a loss of resilience and flexibility.   

FF400 also offers excellent resistance to Rapid Gas Decompression (RGD) damage. This compound has passed multiple industry standard RGD tests with perfect ratings of 0000 in multiple cross-sectional thicknesses. This characteristic is very important in applications such as compressors, valves, pumps, and various subsea equipment where a rapid reduction in gas pressures can cause significant damage to the seals. Having tested at multiple cross-sectional thicknesses, FF400 ensures that no matter the seal size the compound will resist damage caused by rapid gas decompression. It is very common for industry standard requirements such as NORSOK M-710, ISO23936-2, and TOTAL GS EP PVV 142 to be required by customers before a compound is considered for use in an application. Test reports and certifications can be supplied for FF400, as well as several other compounds, by Parker O-Ring and Engineered Seals Division’s Applications Engineering team.

Lastly, Parker’s FF400 compound provides an extremely broad compatibility spectrum for the harshest of oil and gas media. Fluids such as crude oil, water, acids, aromatic hydrocarbons, bromides, brines, amines, and various gases are commonly seen in the oilfield and all can cause issues with rubber sealing compounds. However, one of the most common that is inquired about is compatibility with hydrogen sulfide (H2S) due to its toxicity, corrosive nature, and its presence of various concentrations in naturally occurring oil and natural gas reservoirs. Known also as Sour Gas, the higher the H2S concentration the sourer, more corrosive, and more aggressive the fluid stream becomes for sealing materials. Parker’s FF400 is a great option for these sour gas applications as it has the ability to resist chemical attack, and performs where H2S concentrations can be found at 20% and higher. All of these characteristics make the FF400 an optimal solution for use in compressors, pumps, valves, downhole tools, subsea chokes and other critical devices across the oil and gas industry.

For further information or to see how FF400 can benefit you, visit our website to chat with an engineer or give us a call at 859-335-5101.

This article was contributed by Nathaniel Sowder, applications engineer, Parker Hannifin O-Ring & Engineered Seals Division

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Have you had problems with your polyurethane seals degrading, especially when exposed to higher heat creating the need to replace your seals more often than you would like? As you probably know, seal replacement creates costly downtime that can be avoided if you have an appropriate seal for the job. Parker's Resilon® 4350 polyurethane is up for this task. Resilon 4350 is designed for sealing at higher temperatures up to 250°F continuous and can withstand short-term excursions of up to 300°F without leakage. 

Resilon 4350 polyurethane was formulated to extend the high-temperature capability of Parker’s proprietary urethanes. Where current, more ordinary polyurethane seals have failed, Parker’s new Resilon 4350 has the highest temperature rating of any specialty polyurethane on the market. It was developed for applications where high temperatures or extended heat history cause failures with current polyurethane seal materials.

In a head-to-head comparison test at 250°F continuous, the Resilon 4350 material presented minimal leakage (< 5 grams) up to 250,000 cycles during a life test. This equates to a 33% longer lifespan compared to the standard 4300 material at this elevated temperature range (Figure 1).

Additional testing was completed showing the % seal force retention as the external temperature increased from about 160°F to 250°F. The three materials tested exhibited a linear relationship between the seal force retention and temperature. The Resilon 4350 had a 7-10% higher seal force retention beyond 4300 and the leading competitor of high-temperature polyurethane during this temperature range. The Resilon 4350 still exhibited a 20% seal force retention at 250°F (see Figure 2). Based on the results of this testing, this material is promoted as having a continuous operating temperature range of -65°F to 250°F.

Parker’s Resilon polyurethanes are provided in various profiles for use in a wide variety of applications. With the introduction of Resilon® 4350 the recommended operating temperature range for best performance can now be extended 20° to 25°F higher, giving design engineers the ability to push the envelope.

Follow this link to learn more about Resilon® 4350 and Parker's other Polyurethane 4300 formulations. 

This article was contributed by Eric Woodworth, application engineer, Engineered Polymer Systems Division. 

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EMI shielding gaskets such as conductive elastomer gaskets come in many different materials and almost a limitless number of shapes and sizes.

They are most commonly made of a base material of silicone or fluorosilicone with added conductive fillers such as silver, silver-plated aluminum, nickel-plated graphite, and others. Conductive elastomers represent one of the most versatile products in the category of EMI shielding gaskets.

From a manufacturing perspective, there are two key processes used to create these gaskets: splicing and molding. Check out the detailed list below for information about choosing the process that makes the most sense for you.

Conductive elastomer gaskets are often extruded in long strips, available in bulk or cut to specific lengths. To create custom sized O-rings, the extrusions are cut to the proper length and the ends are adhered (fused) together. Known as splicing, this process utilizes a proprietary adhesive to create an immensely strong bond.

• Bulk material relatively easy to extrude in long lengths, splicing is a process that can allow for quicker turnaround.
• Hundreds of standard extrusion profiles made to match almost any current design requirements.
• When O-ring sizes or design requirements change, splicing can accommodate these changes usually without significant lead time or cost.
• Requires very little or no tooling, meaning low upfront capital investment.
• Can be used with hollow cross-section profiles, creating parts that can accommodate low compression force enclosures.

• Limited in their complexity to singular “loops”.
• Will not retain their shapes like molded O-rings.
• Will not hold to tight tolerances that are common in molded parts.
• There is a limit to how small, in length, gaskets can be spliced.

Molding involves compressing uncured conductive elastomer material into a specially designed mold. The material takes the shape of the mold and retains this shape when cured.

• Allows for a great deal of complexity in parts which can include multiple joints and variability in cross sections across a single part.
• Hold tolerances to within a few thousandths of an inch.
• Will retain the shape in which they were molded.
• In high volumes, molded gaskets can cost less than spliced gaskets as the manual labor is minimized and the process is optimized.
• Can be made in very small o-rings and parts.

• Unless molded gaskets match industry standard gaskets that are commonly available, each new gasket will require a new mold.
• Not compatible with hollow gaskets – molded gaskets cannot have hollow cross sections like spliced extrusions.
• Very large diameters, in length, are not economical.

Between molding and splicing, there is virtually an endless number of profiles and shapes that can be developed. For more information on choosing and designing an EMI shielding gasket, check out the Conductive Elastomer Handbook below.

This blog post was contributed by Ben Nudelman, market development engineer, and Scott Casper, applications engineer, Chomerics Division.

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Have you had problems with your polyurethane seals degrading, especially when exposed to higher heat creating the need to replace your seals more often than you would like? As you probably know, seal replacement creates costly downtime that can be avoided if you have an appropriate seal for the job. Parker's Resilon® 4350 polyurethane is up for this task. Resilon 4350 is designed for sealing at higher temperatures up to 250°F continuous and can withstand short-term excursions of up to 300°F without leakage. 

Resilon 4350 polyurethane was formulated to extend the high-temperature capability of Parker’s proprietary urethanes. Where current, more ordinary polyurethane seals have failed, Parker’s new Resilon 4350 has the highest temperature rating of any specialty polyurethane on the market. It was developed for applications where high temperatures or extended heat history cause failures with current polyurethane seal materials.

In a head-to-head comparison test at 250°F continuous, the Resilon 4350 material presented minimal leakage (< 5 grams) up to 250,000 cycles during a life test. This equates to a 33% longer lifespan compared to the standard 4300 material at this elevated temperature range (Figure 1).

Additional testing was completed showing the % seal force retention as the external temperature increased from about 160°F to 250°F. The three materials tested exhibited a linear relationship between the seal force retention and temperature. The Resilon 4350 had a 7-10% higher seal force retention beyond 4300 and the leading competitor of high-temperature polyurethane during this temperature range. The Resilon 4350 still exhibited a 20% seal force retention at 250°F (see Figure 2). Based on the results of this testing, this material is promoted as having a continuous operating temperature range of -65°F to 250°F.

Parker’s Resilon polyurethanes are provided in various profiles for use in a wide variety of applications. With the introduction of Resilon® 4350 the recommended operating temperature range for best performance can now be extended 20° to 25°F higher, giving design engineers the ability to push the envelope.

Follow this link to learn more about Resilon® 4350 and Parker's other Polyurethane 4300 formulations. 

This article was contributed by Eric Woodworth, application engineer, Engineered Polymer Systems Division. 

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Galvanic corrosion (also known as bimetallic corrosion or dissimilar metal corrosion) is the breakdown of metallic surfaces as a result of the difference in electrical potential of adjacent metals and the presence of an electrolyte.

Stated differently, when two dissimilar metals are in contact in a corrosive environment, one of the metals will begin to corrode. This process is the same one that occurs inside of a battery. The metal that will be corroded and the speed of this breakdown are dependent on the difference in metals and the environment.

For galvanic corrosion to occur, three conditions must be met:

1. Difference in electrical potentials of the two metals in contact with one another

All metals have an electrical potential assigned to them, based on their nobility. Metals such as platinum, silver, and monel have lower corrosion potentials whereas metals such as copper, aluminum, and tin have much higher potentials. Any two dissimilar metals will have a galvanic mismatch and therefore a change of corrosion.

2. Electrical path between the two metals

In situations of EMI shielding, the electrical path is inherently created by the conductivity of the gasket, coating, or sealant.

3. A fluid able to break down the metals

Examples of such fluids can include atmospheric humidity or salt fog environments. As this mist or moisture condenses and collects at the flange or gasket interface, it will create the electrolyte needed to start breaking down the metals.

For aluminum substrates that are going to be exposed to harsh environments such as military and industrial applications, chromate conversion coatings (also known as chem filming) are recommended. On top of this coating would be a conductive or non-conductive top coat. For steels and coppers, nickel or tin plating is often used.

Corrosion-resistant conductive coatings, such as CHO-SHIELD 2000 series conductive paints, are developed with stabilizers to create a very conductive and galvanically inactive surface for high-level EMI shielding in harsh environments.

Because EMI shielding gaskets are in direct contact with structural metal substrates, the corrosion potential must be considered. Historically, conductive fillers have needed to adapt to increasing requirements of galvanic corrosion resistance. Only within the last couple of decades have filler systems such as silver-plated aluminum replaced traditional silver-plated copper or nickel-plated graphite, to dramatically improve corrosion resistance in enclosures that experience moisture and salt fog.

Despite the excellent performance of silver-plated aluminum fillers, the development of a nickel-plated aluminum filler has set the gold standard for both EMI shielding levels as well as corrosion resistance. This filler system, utilizing inherently stable compounds, exhibits the best results on chem filmed aluminum flanges relative to any other filler system, with a 20-50% reduction even compared to silver-plated aluminum.

A properly designed interface requires a moisture-sealing gasket whose thickness, shape and compression-deflection characteristics allow it to fill all gaps caused by uneven flanges, surface irregularities, bowing between fasteners and tolerance buildups. If the gasket is designed and applied correctly, it will exclude moisture and inhibit corrosion on the flange faces and inside the package.

Follow the below steps to maximize corrosion resistance in enclosures:

1. Where other requirements are met, select nickel-aluminum filled elastomers for best overall sealing and corrosion protection.

2. Use silver-aluminum gaskets as the next best alternative to nickel-aluminum filled materials.

3. In aircraft applications, a “seal-to-seal” design can be used with the same gasket material applied to both flange surfaces.

4. Use a Co-extruded or Co-molded gasket – extruded or molded in parallel, these gaskets consist of a conductive and non-conductive elastomer in one piece. The non-conductive material is placed outboard to interface with the moisture, effectively minimizing a key condition causing galvanic corrosion.

5. Coat surfaces with a corrosion resistant plating.

6. Avoid designs that create areas for moisture to pool. Use drainage holes to allow liquids to flow away from the interface.

7. Avoid sharp edges or protrusions such as dovetail grooves that can damage gaskets.

8. Select the proper protective coating and use additional environmental sealants.
    

In order to conduct direct comparative shielding effectiveness testing of gasket panel sets before and after environmental exposure cycling in a standardized test set-up, Parker Chomerics established CHO-TP09. This test method is based on IEEE-STD-299 and takes into account environmental aging conditions such as salt fog, humidity, and extreme temperature cycling.

Proper enclosure design and the implementation of conductive filler systems engineered to minimize galvanic corrosion are key drivers in extending the life span of electronic enclosures and lowering long term maintenance/replacement costs.

Article contributed by Ben Nudelman, market development engineer, Parker Chomerics Division.

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My grandpa used to have a rusty, old air compressor in his shop. As a child, when my siblings and I would visit him, he’d use it to power air wrenches, grinders, and inflate flat soccer balls for us. I noticed it had a port labeled “ADD OIL DAILY” that was covered in the same thick layer of greasy dust as all the other unused junk in his shop. Knowing my grandpa, if asked about adding oil he probably would have said, “Oil is expensive. That’s how the companies get ya!”  The compressor’s seals leaked so badly, you could hear the hissing even over the loud motor. I was certain one day it would explode.

Pneumatic tools are common in factories, tool shops, and DIY garages around the world. Using compressed air for power is convenient, simple, and — when maintained properly — safe and efficient. However, air treatment costs can add up fast. Traditional rubber seals used in air tools require clean, low moisture, compressed air with the proper amount of lubrication added. Good Filter/Regulator/Lubricator systems (FRLs) cost as much as the tools themselves! So, what would happen if we didn’t have to provide pristine air?

Today we have the technology to create seals for tools which don’t require daily or even yearly upkeep. You’ll find these tools labeled “maintenance-free,” which sounds great to the guy responsible for maintenance. It sounds even better to the guy paying for maintenance … and to engineers designing tools who want to keep warranty costs down.

Early pressure seals were made out of leather. My grandpa’s compressor probably wasn’t that old, but even since his time, we’ve come a long way.

When I’m asked for seal recommendations in totally dry-running applications, my mind clicks to a material called PTFE (chemical name polytretrafluoroethylene). Most people know PTFE by the brand name Teflon®1 and are familiar with its use when applied to cookware as a high temperature, slippery, non-stick coating.

PTFE is a semi-hard plastic which feels slick to the touch thanks to its low friction properties. It’s considered self-lubricating because it leaves micro deposits on the sealing surface and reduces friction after just a few strokes. Because of this, it’s good for high-speed sealing and can operate completely dry.

By adding fillers to PTFE, seal manufacturers can tailor materials for greater suitability in meeting performance requirements for a wide range of conditions. String-like additives including fiberglass and carbon fiber increase pressure rating, wear resistance and seal life. Dry lubricant-type additives such as graphite or molybdenum disulfide (MoS2) further increase a seal’s ability to run without lubrication, and at higher speeds and pressures. In pneumatic medical, pharmaceutical, and food processing systems, clean grade mineral-based strengtheners may be used as additives.

PTFE seals for dry running equipment are available in several profile configurations:

• Uni-directional spring-loaded PFTE lip profiles which are good for both linear and slow rotary applications (See Parker's FlexiSeal® Profiles in Catalog EPS5340)
• Dual-acting, O-ring energized "cap" seals for easy installation in linear stroking applications (See Parker's offering in our linear sealing Catalog EPS5370)
• Wear bands which support moving components and prevent contact during shock loading can be made from PTFE for light- and medium-duty systems

For more difficult dry-running applications, tougher engineered plastics such as Nylon, polyester, UHMW-PE, and PEEK are used.

Where cost is the over-riding factor, internally-lubricated rubber elastomer materials are recommended in common, standard profiles:

• For slow speed, lower pressure, completely dry-running applications, a thin, light load lip geometry like Parker's 8400 Profile can accommodate cost, low friction, and low break-away force requirements
• Parker's Standard PolyPak® (SPP) Profile seal tightly at low pressure, and also work great as heavy-duty rod wipers

These common profiles are available in internally-lubricated XNBR (a tougher variant of NBR), which is my go-to rubber for low- and no-lube applications. 

An air compressor was one of the first power tools I bought. I knew little about seals back then and just needed something to top off the air pressure in my car tires and power a nail gun. I purchased one advertised as maintenance-free because I am, after all, my grandfather’s offspring. Oil costs money.

Even though dry systems don’t benefit from the protective aide afforded by lubrication, the same set of “good seal design principles” apply whether the system is fully hydraulic, lightly lubricated, or completely dry. Let’s take a look at a few seal design concepts and elaborate on how a lack of lubrication affects them.

The sliding movement of seals generates heat through friction. Rub your hands together and they get warm. Rub them faster or press together harder, and they get hot quicker. Excessive heat is the enemy of seals; they begin to soften and wear out faster. We counteract this by using tougher materials which can handle the temperature. Alternatively, we can design methods to cool the system.

Pneumatic systems are unique in that they either pull air from outside (compressors) or vent to atmosphere (tools and cylinders). Expanding gas has a small cooling effect on the latter.

Compressing gas generates heat, so compressors are a good example of a worst-case scenario. In addition, they operate at high speed and pressure. The housing of my compressor is covered with fins to help dissipate heat during long run cycles. Seal materials like PTFE, PEEK, and FKM (energizers) are often used because they can handle hot temperatures.

Our catalog recommends a maximum surface roughness of 12 µin Ra for linear and rotary applications. PTFE will benefit from a smoother surface, creating a tighter seal and reducing wear. Applications where leakage is critical, like in cryogenics or when sealing explosive gases, a highly polished finish of 4-6 µin Ra is best.

A minimum hardness of 25 Rc is recommended for linear and rotary applications. Softer materials can be used in light duty applications, but the surface may wear or become grooved over time, especially in rotary applications.

Some PTFE fillers are abrasive. While tough fillers like fiberglass and carbon fiber provide superior wear resistance, we recommend a minimum surface hardness of 60 Rc to prevent abrasion of the hardware. Mild fillers such as graphite, bronze, and aramid fiber are okay with the minimum requirement of 25 Rc.

Dirty air is a problem in all pneumatic systems. If the system is exposed to contaminated air, or to a dirty environment, abrasive particles can accelerate wear of both the hardware and the seals. Using wear resistant materials (like fiberglass-filled PTFE) along with a hardened sealing surface will prolong the life of the equipment.

Seal geometry also plays a role here. Sharp-lipped profiles like our FBD-V FlexiSeal and PolyPak (SPP & DPP) prevent junk from building up under the seal lip and wearing it away. Filling the spring cavities of FlexiSeals with silicone is an option to make the seals easier to clean when used in extremely dirty environments that require equipment washdown.

Air and non-reactive gases like nitrogen are compatible with all seal materials (so long as they’re used within the material’s temperature capability range). Caustic gases like pure oxygen, chlorine, and hydrogen sulfide (H2S) will degrade many seal materials. PTFE is highly resistant to most forms of chemical attack and is a good choice when compatibility is a concern.

PTFE has one weakness and that’s water. The material is extremely hydrophobic. The protective layer that naturally deposits itself on the hardware gets washed away in wet environments. As a result, seals wear quickly. Carbon fiber-filled PTFE and UHMW-PE plastic are recommended in potentially wet applications.

Having helped design dozens of compressors, the geeky engineer side of me is waiting for the compressor I have at home to break so I can look at the seals. It is entirely possible, however, it will keep working for me for tens of years without failing and just maybe, will someday inspire a blog post from my grandkids.

As technology improves, customers are looking for tools which last longer and cost less to operate. At Parker, we are constantly working and testing to provide tougher seal materials and new designs to aid you in making better products. Take a look at our catalogs and reach out to us if you have questions. Thanks for reading!

Recommendations on application design and material selection are based on available technical data.  They are offered as suggestions only.  Each user should make his own tests to determine the suitability for his own particular use.  Parker offers no express or implied warranties concerning the form, fit, or function of a product in any application.

1Teflon is a registered trademark of DuPont.

This article was contributed by Nathan Wells, application engineer, Engineered Polymer Systems Division. 

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Dissolvable and degradable materials are used in oil and gas operations to create high pressures in hydraulically fractured wells, while also minimizing well intervention keeping wells flowing and preventing blockages. These materials are designed to withstand the high pressures and temperatures that are experienced during an application, and then gradually break down into tiny particles that do not need to be recovered. Because these materials naturally dissolve or degrade, operators are not required to run a wire line down the hole to drill them out — saving considerable time and reducing costs.

These innovative materials are gaining popularity in the oil and gas industry. As competition increases in the global energy market, producers seek technologies that will reduce costs and improve well efficiencies. It has been estimated that over the next two to three years, greater than 30 percent of well servicing and stimulation consumables will be dissolvable products (currently less than 10 percent).

Dissolvable metals and degradable elastomers replace the traditional composite products used in completion operations and can be customized to the application, including diameter, composition, strength, and rate of dissolution for common wellbore fluids. More operators are using aluminum-based materials because they are stronger than magnesium alloys, allowing much smaller overlaps (1.8 percent) in ball and seat applications. Thermoplastic elastomers have consistent high tensile strength and elongations for ambient and elevated temperatures, which provides customers with consistent performance over a wide range of temperatures. Parker’s degradable elastomers can be custom designed providing specific engineered shapes meeting the customer’s needs.

Advantages of dissolvables and degradables include:

• Reduced operating costs. Less well intervention is required (no need to drill out), which also reduces the risk of damage to the casing.
• Faster path to production of the well. Dissolvable materials can be formulated to allow for production to begin in as little as 48 hours after deployment, with no need to wait for a coil line crew.
• High product performance to improve the overall completion performance of the well. Degradable materials can be used for pressures exceeding 10Ksi and temperatures exceeding 200°F, providing ideal frac conditions.
• Highly engineered products that can be processed via multiple methods to produce desired shape. Parker provides multiple processing capabilities to produce products that can meet the specific needs of individual wells.
• Opportunity for dual material use for product performance. A wide range of material offerings allows for combined use—for example, elastomer and thermoplastic can be bonded to the aluminum or used in combination.

Dissolvable metals and degradable thermoplastics and elastomers must perform in harsh, corrosive down-hole environments in oil and gas wells. Parker’s dissolvable and degradable products are made with metal, thermoplastics, and thermosets (elastomers), providing operators with a wider range of material options. For example, Parker offers frac balls in delayed-reaction coatings such as PTFE, nickel, and epoxy. Our 94-Series provides a smooth C2-inhibitive coating with no cracks, rough spots, or nodules, which reduces corrosion and extends life cycle.

Because of our comprehensive range of material offerings, Parker can be an operator’s single provider of dissolvable products, allowing customers to reduce their vendor base. Parker also provides customers with inventory management options, further streamlining operations. Proprietary rate of dissolution (ROD) calculators are derived from broad-spectrum dissolution testing on our dissolvable metal products and are a handy tool for optimizing frac design and product selection for specific well conditions.  

Parker engineers work with oil and gas design teams around the world to customize dissolvable and degradable materials for specific applications. Our proprietary materials are compounded in-house; this also allows us to provide quick-turn delivery production orders and sample requests in a matter of days, including optical inspection to ensure tight tolerances, custom labeling, laser marking, and packaging services.

Parker’s dedicated oil and gas sealing experts, dedicated development labs, and processing equipment are at the forefront of emerging applications for dissolvable/degradable technologies in the energy field. For more information, or to discuss your project needs with a Parker engineer, visit us at OTC, booth #3639. Not attending? Visit our webpage to learn more about our high-performance sealing materials for oil and gas applications. 

Now, watch this video to find out more.

This article was contributed by Dana Severson, regional sales manager - oil & gas, Engineered Materials Group, Parker Hannifin.

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Electric vehicle battery covers pose unique sealing challenges in the automotive industry. The significant size of the sealing perimeter, the materials and size of the seal mating hardware, and the aggressive performance requirements (physical and chemical) all play a crucial role in the design of this critical seal. For fully electrified vehicles, battery seals run the full circumference of the vehicle. This large seal is imperative to the performance, life and functionality of the battery which can result in costly repairs and is the most expensive item to replace on an electric vehicle.

With these exacting obstacles in mind, many manufacturers are looking for options on how to seal this critical joint. Two common methods are extruded and spliced homogeneous rubber gaskets and dispensed form in place gaskets (FIP). Deciding which is best requires some evaluation of the pros and cons of each strategy.

Extruded gaskets have many benefits. Parker’s vehicle electrification experts can design and engineer a custom extruded cross section, providing the exact force needed to maintain a seal and keep closure force low with our innovative hollow profiles. Parker’s O-Ring & Engineered Seals Division offers extruded designs in a wide variety of materials to ensure that long term durability, sealing tests, and flammability requirements can be achieved. The extruded gasket sealing strategy often employs a cast or machined groove on the battery cover. If the design requirements do not permit a groove to be included, Parker has a variety of pressure sensitive adhesives (PSAs) that can hold the gasket in place.

Other benefits include:

• Custom design for your application
• Offered in a wide range of materials and temperature ranges
• Improved long-term material performance
• Application equipment not required
• Fully cured material for installation ease
• Instant seal upon compression
• Seals large gaps
• Flexible, accommodating some application movement
• Decrease downtime with improved serviceability over form in place gaskets

The one challenge with extruded seals is installation. As electric vehicle annual volumes continue to increase, it is important to be able to install the gaskets easily and quickly. For this reason, Parker has a variety of tools and methodologies to simplify and speed up installation.

Dispensable form in place gaskets are often used when design for manufacturing specs require a high level of automation. Parker has a range of non-conductive ParPhorm form-in-place (FIP) gasket technologies available.

When evaluating which technology to utilize, customers should recognize that FIP gaskets will require an investment in automation equipment to apply correctly at high volumes. This would include robotics and ample floor space. Additionally, the nature of FIPGs require higher cleanliness on the mating surfaces to ensure that the gasket adheres to the flange adequately. In application, some FIPGs have higher compression set characteristics that lead to less long-term durability of the flange that if not accounted for could lead to failure. Another factor when considering FIPG materials, is the in-line cure time that can be prohibitive depending on your production process. Finally, many battery manufacturers require that the gasket be easily serviceable so that mechanics can open and close the cover as needed over the life of the vehicle. FIPGs adhere to the cover in such a way that makes removing the gasket more difficult than an extruded or molded seal and could complicate the serviceability of the joint.

Sealing the electric vehicle battery perimeter is critical. Parker’s engineering experts are here to guide you through the decision-making process, customizing a sealing strategy that works best for your requirements. Whether you choose extruded, form-in-place or some other alternative, contact our engineering team today to help. Visit us online and chat directly with an engineer today.

This blog was written by Miles Turrell, electric vehicle applications engineer, Engineered Materials Group

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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 represents the best-in-class material for applications needing to seal phosphate-ester-based fluids. The latest news is that EM163 meets the full qualification requirements of both NAS1613 Revision 6 (code A) and the legacy Revision 2 (no code). We’ve 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 unaged, plus temperature retraction requirements, aged and unaged, 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.

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?

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.

 Table 1: AS1241 fluids

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.

Last, 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.

For more information on this or other topics, visit Parker O-Ring & Engineered Seals Division online and chat with our experienced applications engineers or email us at oesmailbox@parker.com.  

This article was contributed by Dorothy Kern, applications engineering manager, Parker O-Ring & Engineered Seals Division.

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Conductive elastomer EMI shielding gaskets use metallic particles to create a conductive path and shield enclosures from electromagnetic radiation. A key measurement of these gaskets is Electrical Volume Resistivity. Gaskets that have a lower DC resistivity generally indicate a more conductive particle. In many cases, this lower resistance / higher conductivity is associated with better levels of shielding effectiveness. This explains why gaskets with silver particles, which are very conductive, often out-perform gaskets with graphite particles. However, this is not always the case.

A common misconception is that a measurement of DC resistivity can directly predict shielding effectiveness. Over the years, material science evolution has proven that EMI gaskets with higher DC resistance can produce higher levels of shielding effectiveness in some cases compared to gaskets with low measured DC resistance.

How can that be possible, a conductive elastomer EMI gasket with 20x greater DC resistivity that actually has a HIGHER shielding effectiveness? Well, that's because there are many factors have an impact on shielding effectiveness of a conductive elastomer EMI gasket and the volume resistivity value is only one. Other aspects of EMI gasket material and enclosure seam design which can effect shielding effectiveness are as follows:

1. Particle morphology – size and shape – ability to bite through conversion coatings
2. Elemental composition of the particle – i.e. permeability, absorption properties
3. Elemental composition of the plating on the particle – i.e. permeability, absorption properties
4. Plating thickness
5. Compounding control and filler loading %
6. EMI gasket surface conductivity and volume resistivity
7. EMI gasket geometry
8. EMI gasket footprint contact size on mating surfaces
9. Gasket deflection %

• Type of metal substrate – aluminum, steel etc.
• Conversion coating or plating finish
• Fasteners/bolts – quantity, separation, generated gasket compression load
• Gasket groove (if used)
• Ancillary metal to metal contacts

Check out the Parker Chomerics Conductive Elastomer Handbook for more information on EMI Shielding Theory and the specific properties of various types of conductive elastomers.

This blog post was contributed by Ben Nudelman, market development engineer, Chomerics Division.

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Hydraulic sealing systems used in aviation technology applications are exposed to particularly challenging ambient influences such as extreme temperature fluctuations and aggressive pressure media. Major temperature fluctuations and aggressive media cause sealing materials to age faster than those used in conventional applications, resulting in impaired seal performance. Consequently, these application conditions and special mating surfaces require sealing systems that meet the required range of performance at high levels of reliability.

Rod seals for cylinders and actuators seal the applied system pressure toward the atmospheric side. They perform a critical function in preventing external leakage that may contaminate the immediate environment. The rod seals LB and LS have been specially developed for the safety-critical applications in aviation and offer high reliability and wear resistance due to their seal geometry and material selection.

Application examples:

• Flight Control Systems
• Propeller Engines
• Landing Gear Systems
• Aircraft doors
• Engine Nacelles

The LB rod seal is used when particularly high sealing performance and wear resistance are required and conventional compact seals do not satisfy the specific demands of the aviation industry. 

It consists of an NBR lip ring and a PTFE anti-extrusion ring. Among other things, it is characterized by exceptionally high static and dynamic sealing performance which is achieved by optimized seal geometry on the static and on the dynamic side of the seal. 

A back-up ring on the back of the seal provides improved extrusion resistance. When appropriate materials are selected, the LB rod seal is suitable for wide temperature ranges. If required, its wear resistance can also be further enhanced significantly by selecting suitable materials.

Advantages of the LB rod seal include:

• Exceptionally high static and dynamic sealing performance.
• Good wear resistance.
• Robust seal profile for harshest operating conditions.
• Insensitive to pressure peaks.
• High extrusion resistance.

Range of application

• Operating pressure             ≤ 350 bar
• Operating temperature       -55 °C to +125 °C
• Sliding speed                       ≤ 0,5 m/s

The LS rod seal is particularly well-suited for high temperatures. It consists of a PTFE rod sealing ring, a PTFE anti-extrusion ring and an elastomer O-ring as a preloading element. Due to its wide variety of material combinations, it is characterized by a diverse range of applications – particularly in use with aggressive media and in wide temperature fields. The additional back-up ring at the back of the seal enhances extrusion resistance when pressure peaks occur and thus significantly increases the service life of the sealing system. The width of the back-up ring can be adjusted according to the groove so that in many cases there is no need for modification of an existing groove.

Advantages of the LS rod seal include:

• Exceptionally high static and dynamic sealing performance.
• Good wear resistance.
• Minimal break-away and dynamic friction and no stick-slip tendency ensures uniform motion even at low speeds.
• Insensitive to pressure peaks.
• High extrusion resistance.
• Adaptable to nearly all media thanks to high chemical resistance of the sealing ring and large O-ring compound selection.
• High temperature resistance in case of suitable compound selection.

Range of application

• Operating pressure             ≤ 400 bar
• Operating temperature       -55 °C to +200 °C
• Sliding speed                     ≤ 4,0 m/s

Learn more in our Brochure: Rod Seals for Hydraulic and Electromechanical Actuators in Aviation (MIL-G-5514 / AS4716)

This blog post was contributed by Fabio Bueti, market unit manager aerospace, and Selim Alacali, application engineer aerospace, Engineered Materials Group Europe, Prädifa Technology Division

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We are coming up on two years since the birth of FF156-75 and this compound is one worth celebrating.  If you don’t know what FF156 is, thank you for taking a few minutes to read this blog.

FF156 is the most versatile, value-packed perfluorinated (FFKM), material offered by Parker. The versatility of the material means it solves problems in many different markets: Chemical Processing, Life Science, and a range of demands needed by General Industrial markets.

Most surprising is the steam and high temperature water resistance.  Most fluorocarbons (FKMs) and FFKMs do not fair well in steam. You might be familiar with Parker’s specialty steam resistant FFKM: FF580 and FF582. Both of these materials offer excellent resistance to steam, perhaps the best in the market. You can see the change at 121°C comparing both FFKMs after three days of exposure and then again after seven days.  You might notice there is not much change at 121°C between the two lengths of time. 

Figure 1 Pulled from ORD 5764

Raising the heat to 260°C, you can see how FF156 still holds it’s own compared to the specialty grade of FF580. 

FF156 stacks up quite nicely in steam against our best steam compatibility rated FFKM materials. In addition to steam compatibility, the material has passed USP class VI testing requirements demonstrating the required cleanliness needed for biocompatibility. The combination of USP class VI and suitability for sterilization process is why FF156 is a sealing solution for demanding applications in the Life Science Market.

You might be wondering, why is FF580 even needed, since FF156 has such favorable performance? That comes back to the “value-packed" versatility of FF156. FF580 has a wider breadth of resistance to harsh, nasty chemicals. If you are familiar with the perfluorinated family as a whole, you know they can withstand the most aggressive chemicals, but at a hefty price. FF156 was formulated to have outstanding chemical resistance but was not intended to be a silver bullet FFKM material like FF580.  In the general industrial market where high temperature applications seal steam or diluted concentrations of chemicals, FF156 is a great way to extend seal life without the high expense of a specialty FFKM.

FF156 is available as molded O-rings, but also in extruded and machined profiles, spliced hollow seals, hollow and window pane configurations or custom molded shapes.  For more information or to see if  FF156 is right for your application, please reach out to a Parker Application Engineer.

This article was contributed by Dorothy Kern, applications engineering manager, Parker O-Ring & Engineered Seals Division.

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As automatic transmissions become more advanced as a system, the components within must evolve as well. Performance drives the design and there are many factors that must mesh together to achieve the overall goal.

Improved efficiency is the leading factor when it comes to system improvement. The move to eight, nine, and ten-speed automotive transmissions are focused around improving fuel economy. Obviously, with the increased number of gear ratios, the number of clutches and clutch pistons has also increased. A reduction in the amount of energy needed to engage and retract a clutch piston directly reduces the parasitic loss of energy within the entire system. This has resulted in a significant focus on the impact of seal drag within each clutch piston. 

For more than a decade, D-Rings have been the preferred sealing technology for automotive transmission clutch pistons as they provide several advantages to other seal designs including:

• Bi-directional sealing capability,

• Symmetrical design simplifies assembly,

• Lower drag than other radial compression seal designs,

• Reduced variation in drag response, and

• Eliminates potential spiral failure existent with O-rings.

In the past, there was always enough fluid pressure to overcome seal drag and activate the clutches. Because these same size pumps must supply so many more clutch circuits in the transmission, this energy supplied is in greater demand. Similarly, heavy springs in the past provided enough return force to ensure immediate disengagement of the clutch. Limited availability of space, as well as lower cost targets, have resulted in smaller, lower force return springs.

Our engineers have developed a low drag D-ring which reduces the drag forces in the application by 50%. All other advantages of D-ring seals are maintained including the symmetrical profile which simplifies the assembly process. This improves the first time through capability and reduces warranty costs.

By creating volume space to which the deflected rubber can easily flow to, the reaction forces against the mating surface (normal force) is reduced while still maintaining sufficient sealing forces.

In addition, Parker’s unique manufacturing approach provides a significant cost reduction over compression and injection molded designs. The absence of mold parting lines in this new technology also eliminates molded rubber flash on the sealing surface which is inherent with injection or compression molded products.

Lower clutch seal drag provides several advantages including:

• Smoother shifts,

• Overall improvement in system efficiency, and

• Smaller return springs save space, weight, and cost.

This technology is also available for applications beyond transmission clutches. Any reciprocating piston application can benefit from low drag D-rings. Examples would include active differentials and other torque management applications.

Please contact one of Parker’s application engineers to discuss how low drag seals can improve the performance and efficiency of your applications.

Article contributed by Scott A. Van Luvender, automotive applications engineering manager, Engineered Materials Group






 

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EMI shielding of electronics using thermoplastic housings traditionally has been a complex and costly process. Today, OEMs not only have to meet form, fit and function requirements, but also must reduce the total cost of ownership, reduce weight, simplify the supply chain and reduce time-to-market.

For these reasons, OEMs will benefit from using a full-service, single-source supplier who can simplify these challenging responsibilities by taking on these tasks and more such as:

• Provide technical expertise in the dispensing, curing and spraying of sophisticated materials
• Reduce complex material requirements of tens of parts down to a single stock keeping unit
• Reduce the size of inventory and eliminate a layer of inventory management processes
• Support customers' quality processes such as the automotive industry's PPAP (Production Part Approval Process) scheme and aerospace and defense certifications

Incorporating expert materials

Parker Chomerics offers an integrated assembly service which pre-assembles and dispenses its products into a housing, heat sink assembly or substrate and delivers a custom product or sub-system according to the customer’s design specification. The sub-system incorporates expert materials such as engineered plastics, thermal interface materials, electrically conductive elastomers and coatings, some of which require expert processing to guarantee quality and functionality. 

Making choices

Selecting a suitable plastic injection molding partner is not as straightforward as it sounds when it comes to electronic enclosures. This is where design assistance from a reputable expert in EMI shielding will be invaluable. Because the optimization of part geometry will lead you to the highest performance with the lowest possible processing, material and tooling cost.  

Additionally, upon part design completion, mold flow analysis will help create a 3D representation of flow patterns for the injection molding process. As a result, it is possible to visualize flow rates, pressures and temperature values across the entire part, therefore helping adjust the molding process by locating entry gates and compensating for variable pressures or cooling rates to avoid part warpage or uneven shrink rates. A specialist in this area will also be able to source the tooling, build the optimum mold and provide full PPAP reporting back to the customer.

With over 300 different polymer materials available for design engineers to consider, expert advice can prove invaluable.  

A superior choice for plastic housings is Parker Chomerics PREMIER™ PBT -- available in two offerings, one that delivers excellent hydrolysis resistance, the other superior 5VA flame retardant, PREMIER PBT improves long term aging performance when exposed to extreme heat and humidity.  It is a superior choice due to its high shielding effectiveness and enhanced mechanical strength.  Also, being a single pellet composition, it eliminates inconsistent mix ratio problems common with multi pellet blends.

Non-conductive thermoplastics can also be used with secondary EMI coatings.  These are most suitable for parts requiring high temperature resistance, chemical resistance, low water absorption, thin walls or those requiring shielding effectiveness > 85 dB.

Parker Chomerics can help with additional processes such as conductive painting, sputtered vacuum metallization, electroless plating and thermal spraying.

The primary design factors to consider when choosing a secondary EMI coating are

• Shielding effectiveness
• Environmental resistance
• Component geometry
• Production volume

For example, sputtered aluminium is a good solution in low-shielding applications where volume supports a higher tooling cost. Alternatively, while Ni/Cu provides excellent shielding, this coating is not generally recommended for use in high-humidity uncontrolled environments, while thermal spraying of tin-zinc provides high shielding with excellent resistance to harsh environments.

Often plastic housing needs assembly of a secondary component.  These elements can be assembled onto the housing using processes such as heat staking, sonic welding, solvent bonding and mechanical assembly. Depending on the part, assembly can often be done at the injection molding press, within the cycle time, consequently saving money for the customer.

Often the device will need EMI shielding, thermal management components or an optical display filter, in line with the customer requirements.  Depending on the application, materials may include extruded, molded or form-in-place EMI gaskets, thermally conductive pads or gels, microwave absorbers or optical displays. These materials can be dispensed, over-molded, bonded, mechanically fastened or incorporated into the design to become an integral part of the housing. This simplifies final assembly, allowing OEMs to have only one part to order, inventory and handle.

Another benefit of integrating all these components using a single-source supplier is that testing of the EMI package and board level design can be done at the beginning of the design cycle therefore eliminating the need for rework and changes further down the line. Specialists can offer full service compliance testing to meet emissions, immunity, susceptibility and safety requirements and is able to solve virtually any EMC/EMI problem that testing may reveal.

Ultimately, through the selection of a single-source supplier who can provide integration of all design and production capabilities globally, it is possible to reduce cost, reduce weight (in metal-to-plastic conversions), reduce time to market and produce a fully integrated assembly that best suits the customers global footprint. Chomerics' Integrated service allows customers anywhere in the world to design a sub-assembly including EMI shielding solutions and TIMs, and then partner with Chomerics to assemble it.

This blog post was contributed by Mel French, marketing communications manager, Chomerics Division Europe.

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The 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.

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.

Parker Engineered Polymer Systems (EPS) Divisionmanufactures 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. Whether full degradation is needed in hours, days or weeks, Parker’s in-house testing capabilities and material development chemists can assist in recommending the proper parameters for use of degradable elastomers in your application. For more information, or to discuss your project needs with a Parker engineer, contact us or visit us at our Oil and Gas webpage.

This article was written in collaboration and contributed by:

Jacob Ballard, research and development engineer, Parker Hannifin O-Ring & Engineered Seals Division

Jason Fairbanks, market manager, Parker Hannifin Engineered Polymer Systems Division

Nathaniel Sowder, business development engineer, Parker Hannifin O-Ring & Engineered Seals Division

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Whether it be a classic automotive transmission design or the latest in electric vehicle technology, there is always a need to move high-pressure fluid through different operational systems.

Cooling systems are required for the battery storage compartment in both hybrid and fully electric vehicles. Whether the system is water or oil cooled, these fluids need to be pushed around and through various components to dissipate the unwanted heat.

Automatic transmissions have an elaborate series of fluid circuits, or passages, required to feed the oil necessary to engage the hydraulic clutches. This is especially true with the newer eight, nine, and ten-speed transmissions. This increase in the components within the transmission also reduces the amount of available space for each clutch requiring that all space within the transmission case be used with the utmost efficiency.

Movement of fluid from the pump to the main control, to the appropriate clutch, sometimes requires the most direct route. This can require cutting through and/or across different components opening up potential leak paths in the circuit. In other applications, the circuit may need to be manipulated around components or systems that cannot be moved. A large leak can cause only partial engagement of the clutch piston resulting in a burnt clutch and very costly repair or even rebuild of the transmission. Even a small fluid leak results in a loss of system overall efficiency.

In the past, many of these joints were sealed utilizing an O-ring placed in a shallow counterbore and compressed axially against the mating component. These seals were prone to becoming dislodged before the mating component could be assembled resulting in cut seals or even the seals missing altogether. In addition, having different sized ports in close proximity to each other often resulted in the O-rings being mixed up into the wrong locations.

Parker engineers have developed multiple fluid transfer sealing technologies that can be customized for different applications. Designed with a metal insert to provide resistance to seal extrusion into the gap between components under fluid pressure, the boot type sealing lip configuration can accommodate wider axial tolerance stack conditions without losing sealing performance. In addition, the ribbed outer diameter provides a low assembly force interference fit into the bore. Secure positioning of the seal in the bore is ensured until the mating component is secured into place. Mis-builds are eliminated, thus improving first time through capability and reducing warranty costs.

Custom multi-port configurations can be designed to meet specific application needs. The positioning of the different seals in the carrier reduces complexity by providing a single component solution. Mixed seal locations are also eliminated.

Many different elastomers are also available to meet specific application requirements. Our Parker chemists have compounds available to ensure performance for chemical compatibility to the media being sealed, as well as solutions for very high or even very low-temperature applications. Custom materials can also be developed to satisfy unique requirements.

Please contact one of Parker O-Ring & Engineered Seals Division applications engineers who can assist you in solving your fluid transfer sealing system needs.

Article contributed by Scott A. Van Luvender, automotive applications engineering manager, Engineered Materials Group.

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A common question often asked by our customers is the reason why flow rate is reported on datasheets of liquid-dispensed thermal interface materials instead of viscosity. And it’s a fair question; viscosity is a fundamental property of fluids such as thermally conductive pastes. But measuring viscosity, however, is more complicated than meets the eye.

Parker Chomerics THERM-A-GAP Thermally Conductive GELs belong to a class of fluids referred to as “thixotropic.” In case you’re not familiar, thixotropy is a time-dependent decrease in viscosity as shear stress is applied.

This shear stress may be introduced during mixing, pumping, or dispensing of the product. The extent of the viscosity decrease depends of the duration and magnitude of the agitation, and viscosity recovers gradually over time after the stress is removed. The act of measuring viscosity introduces shear stress, so gathering repeatable data requires carefully controlling the duration of the test and the relaxation time between trials.

To complicate the measurement further, viscosity is strongly influenced by sample temperature. A warmer dispensable thermal paste flows more quickly than one at room temperature, a characteristic that is particularly relevant in thermal interface materials.

Therefore, a viscosity measurement is only accurate for a given shear stress, duration, and temperature. The resulting value of viscosity is difficult to generalize, so it is more convenient to use flow rate, as it is a measurement that is more representative of actual end-use conditions.

Automated dispensing is one of the primary advantages of dispensable thermal pastes, such as Parker Chomerics THERM-A-GAP GELs. Publishing flow rate data provides a framework with which to compare different gels based on their dispensability.

Additionally, measuring flow rate instead of viscosity controls the critical parameters described above, such as:

• Shear stress, which is controlled by dispensing from a specified container at a constant pressure
• Test duration
• Ambient temperature

Measuring flow rate is repeatable and more representative of actual dispensing situations than a viscosity value.

So, the next time you’re reading a datasheet, you’ll be armed with the knowledge that flow rate is a more accurate representation of real-world conditions.

This blog post was contributed by Jon Appert, R&D engineer, Chomerics Division.

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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 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.

 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.

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.

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 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.

For some applications, a critical component of selecting a seal material is a phenomenon known as “outgassing”. However, even within the elastomer community, outgassing is not something that is commonly considered. Which begs the questions: what is outgassing and why is it important? Outgassing is usually most relevant in vacuum applications, where the vacuum causes the elastomer to release constituent material. The constituent material could include water vapor, plasticizers, oils, byproducts of the cure reaction, or other additives used in the seal material. Outgassing becomes a problem if a thin film of those chemicals condenses and is deposited on nearby surfaces. Such a film poses major challenges in highly sensitive applications, such as optics or electronics, where cleanliness is of utmost importance. A seal material with low outgassing  is essential because it shows the seal material does not emit volatile constituents under vacuum conditions.

Outgassing is most often characterized by weight loss of the seal material. The ASTM test method E595 is one way to quantify outgassing by measuring Total Mass Loss (TML %), Collected Volatile Condensable Materials (CVCM %) and a reported value for Water Vapor Regain (WVR %).  Measurements are taken following a 24 hour exposure to vacuum of 5x10-5 torr at a temperature of 257°F.

Taken together, these three parameters tell a complete story. The TML is reported as the percent of the specimen’s initial weight that is lost during the test; under standard criteria, the result must be less than 1.00% mass loss. Obviously, minimizing TML is a good thing, but it is not the only important factor. Collected volatile condensable material (CVCM) is the amount of outgassed matter from a specimen that condenses onto a collector during the maintained time and temperature. CVCM is of particular concern because any material that readily condenses in the test is likely to condense on and contaminate nearby surfaces during use. To pass the standard CVCM requirement, the amount collected relative to the initial mass of the specimen must be less than 0.10%. The final measurement, WVR, is the mass of the water vapor absorbed by the specimen after a 24-hour stabilization at 23°C in a 50% relative humidity atmosphere. There is seldom a pass/fail limit for WVR; instead this result is merely reported. In many applications, the small amount of water vapor lost by a seal may not be of concern, particularly if the application already includes a means of controlling moisture. Further, any WVR is presumed to be equal to the portion of original TML that was water vapor. The difference between TML and WVR is therefore presumed to be volatile organic material that has evaporated out of the material (only some of which condenses in the CVCM test), so minimizing the difference between TML and WVR is also of considerable importance.

To illustrate, we can look at the most recent outgassing data completed on a few popular low temperature fluorocarbon materials. Table 1 contains the results from a 3rd party laboratory to measure the outgassing properties of VM125-75 and VX065-75. Both had undetectable amounts of CVCM and very small differences between TML and WVR.  VX065-75 in particular displayed remarkably little outgassing as well as a low WVR.

There are a few additional resources detailing seal materials that are known for having low weight loss. The O-Ring Handbook ORD 5700, Table 3-19 (page 65 of the pdf), has a few legacy materials with weight loss percent after a two-week exposure to 1 x 10-6 torr vacuum level, at room temperature. Additionally, non-Parker resources such as the NASA website contain an interesting summary of a much broader range of materials.  

For more information on low outgassing seal materials, please contact a Parker Application Engineer at OESmailbox@Parker.com or 859-335-5101.

This article was contributed by Dorothy Kern, applications engineering manager, Parker O-Ring & Engineered Seals Division.

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We're thrilled to announce that the Chomerics Division of Parker Hannifin Corporation, the global leader in motion and control technologies, has been recognized for its outstanding quality by global vehicle manufacturer Fiat Chrysler Automobiles (FCA) for both its production part and Mopar® unique parts partnership for the calendar year 2018.

This award, which specifically refers to Parker Chomerics Engineered Plastics Solutions business unit in Fairport, NY, has been awarded because of Parker Chomerics’ excellent performance as an FCA supplier.

In a letter from Scott Thiele, head of purchasing and supply chain for FCA North America, Thiele emphasizes Parker Chomerics’ “exceptional performance and dedication to excellence.” The letter goes on to detail how Parker Chomerics has achieved outstanding quality on a variety of metrics from production, to warranty, and the development of a stringent quality management system.

“Congratulations to the entire Fairport team, this is a great accomplishment. We are so honored to be among the very few that receive this coveted award. My hat goes off to the entire team for their dedication and collaboration throughout the year.”

David Hill, Parker Chomerics global general manager

Parker Chomerics Engineered Plastic Solutions business unit in Fairport, NY, located 10 miles outside of Rochester, NY, heavily utilizes robotics and automation to achieve high quality and delivery standards for many industries.

For more information on Parker Chomerics products, visit our website or download our Engineered Custom Injection Molded Plastics Solutions brochure. 

This blog was contributed by Jarrod Cohen, marketing communications manager, Parker Chomerics Division.

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