Guide to bearings

Engineering Basics: Guide to O-Rings

O-Rings are the most widely used seal for they offer an efficient and economical sealing element for a wide range of static or dynamic applications and are easy to use due to their inexpensive production methods. A broad range of elastomer materials for both standard and special applications allow the O-Ring to be used to seal practically all liquid and gaseous media.

The o-ring manufacturing process is quite straightforward, and the specifics of any given o-ring design and production run generally take into account required quality, quantity, application environment, cost-effectiveness, chemical and pressure compatibility, longevity and lubrication requirements. O-rings are usually produced using a variety of manufacturing techniques like extrusion, injection molding, pressure molding or transfer molding.

The purpose of this guide is to help you get familiar with the most common types of O-rings, norms, their design particularities and operating mode, the way they handle forces, the proper installation and maintenance procedures, as well as the most frequent problems that can cause the damage of O-rings.


1. Norms

O-rings are manufactured in accordance with a variety of standards for different countries:

Standard Description
BS 1806 British standard for inch series O-rings.
This standard has the same development roots as the AS-568B standard, and it incorporates some additional sizes.
SAE AS568B American standard for O-rings. AS-568 is the Aerospace Standard (AS) as well as the SAE standard
BS 4518 British standard for metric series O-rings.
SMS 1586 Swedish metric standard
DIN 3771-1 German metric standard for fluid-sealing O-rings.
ISO 3601-1 International standard for metric and inch series O-rings.
The second edition includes the requirements for Aerospace (AS) applications.
JIS B2401 Japanese industrial standard for metric series O-rings.
This standard now includes the second edition of ISO 3601-1.
NF T47-501 French standard for O-rings.
This standard is similar to the ISO 3601 and the DIN 3771 standards with some unique class designations.

Full O-rings assortment Eriks

Assortment O-Rings

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2. Sealing Principle

O-rings are bi-directional seals, circular in shape and cross section. O-rings are generally made of an elastomeric material, but may be made of other materials such as PTFE or metal.

An O-ring seals through the deformation of the seal material by installation and media pressure to close off the gap between mating components. Higher system pressures can cause deformation through the gap, known as extrusion, resulting in seal failure. Choosing a harder seal material or installing back-up rings to support the O-ring may alleviate this problem.

The rubber O-ring should be considered as an incompressible, viscous fluid having a very high surface tension. Whether by mechanical pressure from the surrounding geometry or by pressure transmitted through the hydraulic fluid or gas, this extremely viscous (elastomeric) fluid is forced to flow in the gland to produce zero clearance or a positive block to the flow of the media being sealed. The O-ring absorbs the stack-up of tolerances of the unit and its memory maintains a sealed condition.

Sealing Principle

The tendency of an O-ring to return to its original shape when the cross section is deflected is the basic reason why O-rings make excellent seals. The squeeze or rate of compression is a major consideration in O-ring seal design. Elastomers may take up the stack-up of tolerances of the unit and its memory maintains a sealed condition. O-rings with smaller cross sections are squeezed by a higher percentage to overcome the relatively higher groove dimension tolerances.

Sealing Principle

3. Application Design

O-rings can be successfully used in static as well as dynamic applications. A seal that does not move, except for pulsation caused by cycle pressure, is called a static seal.

Those seals that are subjected to movement are dynamic seals. These are further defined as reciprocating (seals exposed to linear motion) and rotary (stationary seals exposed to a rotating shaft).

Overview Application Design

Static applications

There are four varieties of static applications: axial, radial, dovetail and boss seals.

Picture Application Description
Axial Design Axial The O-ring cross section is squeezed axially in the groove similar to a flat gasket.
Radial Design Radial The O-ring cross section is squeezed radially in the groove between the inside (ID) and outside (OD).
Dovetail Design Dovetail The O-ring is also axially squeezed in a dovetail groove.
The groove design allows the O-ring to be retained in the face seal during assembly and maintenance.
This is beneficial for special applications where the O-ring has to be fixed by the groove e.g. a lid which opens regularly.
Bosstail Bosstail The O-ring is used for sealing straight thread tube fittings in a boss.
A boss is a cylindrical projection on a casting or forging. The end of that projection is machined to provide a flat, smooth surface for sealing.
Straight threads used with an O-ring provide a better seal than tapered threads used alone.

Dynamic applications

There are three varieties of dynamic applications: reciprocating, oscillating and rotary.

Picture Application Description
Reciprocating Reciprocating Reciprocating seals refer to seals used in applications that slide back and forth.
This motion introduces friction, which creates design considerations different from those of static seals.
The O-ring may be housed in a groove (rod seal) in the cylinder wall instead of a groove in the piston surface (piston seal) without any change in design limitations or seal performance.
Oscillating Oscillating Oscillating applications are those seeing both rotary and reciprocating movement.
A valve spindle is an example of an oscillating application.
Rotary Rotary Rotary seals refer to seals used in applications that rotate.
Miscellaneous applications Miscellaneous applications O-rings are used in a variety of applications. Wipers, buffers, and drive belt applications are just some of the examples.

Squeeze or rate of compression of O-Ring

The tendency of an O-ring to return to its original shape when the cross section is deflected is the basic reason why O-rings make excellent seals. The squeeze or rate of compression is a major consideration in O-ring seal design and differs per O-ring application design.

O-rings with smaller cross sections are squeezed by a higher percentage to overcome the relatively higher groove dimension tolerances.

In static applications the recommended squeeze is usually between 15-30%. In some cases the very small cross sections can even be squeezed up to 30%. In vacuum applications the squeeze can even be higher. Squeezing more than 30% induces additional stress which may contribute to early seal deterioration.

In dynamic applications the recommended squeeze is between 8-16%; due to friction and wear considerations, smaller cross sections may be squeezed as much as 20%.

4. Material

Rubber materials or elastomers used in sealing applications are often described as compounds; meaning that they are a mixture of ingredients manufactured under specific conditions. A compound typically comprises a polymer, cross-link system, fillers and other ingredients used to achieve specific manufacturing-, application- or cost requirements.

The basis of compound design is a selection of the polymer type. To the elastomer, the compounder may add reinforcing agents, such as carbon black, colored pigments, curing or vulcanizing agents, activators, plasticizers, accelerators, antioxidants or antiradiation additives. There may be hundreds of such combinations.

Different circumstances demand various compound properties. That is why so many compounds have already been developed. We have categorised our compounds in standard- (general purpose), specialist-(industry or application specific) and high performance grades.

Hardness of elastomer

One of the most frequently named properties regarding polymer materials is hardness. Hardness is the resistance of a body against penetration of an even harder body of a standard shape at a defined pressure.

There are two procedures for hardness tests regarding test samples and finished parts made out of elastomer materials:
Shore A / D in accordance with ISO 868, ISO 7619-1, ASTM D 2240 Most elastomers are measured on the Shore A scale. Shore A hardness of 35 is soft; 90 is hard. Shore D gauges are recommended where the Shore A rating is greater than 90.
Durometer IRHD (International Rubber Hardness Degree) in accordance with ISO 48 , ASTM 1414 and 1415

The softer the elastomer, the better the seal material conforms to the surfaces to be sealed and lower pressure is required to create a seal. This is particularly important in low pressure seals that are not activated by fluid pressure. The softer the elastomer, the higher the coefficient of friction.

In dynamic applications however, the actual running and breakout friction values of a harder compound with lower coefficients of friction are higher because the load required to squeeze the harder material into the O-ring groove is much greater.

The softer the elastomer the more risk that at high operating pressure the elastomer of the O-ring will extrude into the clearance gap between the mating seal surfaces.

The harder materials offer greater resistance to flow. With an increase in temperature, elastomers first become softer and then eventually harder as the rubber curing process continues with the application of heat.

General Overview over the basic elastomers

Here you can find a general overview over the commonly used elastomers:

Overview Material

This information is only a guideline. Chemical compatibility lists should be consulted (here you can find the ERIKS Chemical Resistance Guide). ERIKS will provide this on request. Whenever possible the fluid compatibility of the O-ring compound should be rated "A". For a static seal application a rating "B" is usually acceptable, but it should be tested. Where a "B" rated compound must be used, do not expect to re-use it after disassembly. It may have swollen enough that it cannot be reassembled. When a compound rated "C" is to be tried, be sure it is first tested under the full range of operating conditions.

It is also particularly important to test seal compounds under service conditions when a strong acid is to be sealed at elevated temperatures because the rate of degradation of rubber at elevated temperatures is many times greater than the rate of degradation at room temperature.

Description of the most common basic elastomers

NBR - Acrylonitrile butadiene, Nitrile or Buna N

Nitrile, chemically, 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 (-35°C to +120°C), nitrile is the most widely used elastomer in the seal industry today. Also many military rubber specifications for fuel and oil resistant O-rings require nitrile based compounds. It should be mentioned that to obtain good resistance to low temperature, it is often necessary to sacrifice some high temperature resistance.

Nitrile compounds are superior to most elastomers with regard to compression set, tear, and abrasion resistance. Nitrile compounds do not possess good resistance to ozone, sunlight, or weather. They should not be stored near electric motors or other ozone generating equipment. They should be kept from direct sunlight. However, this can be improved through compounding.

NBR is the standard material for hydraulics and pneumatics. NBR resists oil-based hydraulic fluids, fats, animal and vegetable oils, flame retardant liquids (HFA, HFB, HFC), grease, water, and air.

Special low-temperature compounds are available for mineral oil-based fluids. By hydrogenation, carboxylic acid addition, or PVC blending, the nitrile polymer can meet a more specified range of physical or chemical requirements.

HNBR - Hydrogenated nitrile, or highly saturated nitrile

HNBR has recently been developed to meet higher temperatures than standard NBR while retaining resistance to petroleum based oils. Obtained by hydrogenating the nitrile copolymer, HNBR fills the gap left between NBR, EPDM and FKM elastomers where high temperature conditions require high tensile strength while maintaining excellent resistance to motor oils, sour gas, amine/oil mixtures, oxidized fuels, and lubricating oils.

HNBR is resistant to mineral oil-based hydraulic fluids, animal and vegetable fats, diesel fuel, ozone, sour gas, dilute acids and bases. HNBR also resists new bio-oils (biological oils). HNBR is suitable for high dynamic loads and has a good abrasion resistance. HNBR is suitable for temperatures from -30°C to +150°C (-20°F to +302°F).

XNBR - Carboxylated nitrile

The carboxyl group is added to significantly improve the abrasion resistance of NBR while retaining excellent oil and solvent resistance. XNBR compounds provide high tensile strength and good physical properties at high temperatures. XNBR is suitable for temperatures from -30°C to +150°C (-20°F to +302°F).

NBR/PVC - Nitrile/PVC resin blends

PVC resins are blended with nitrile polymers to provide increased resistance to ozone and abrasion. The PVC also provides a significant improvement in solvent resistance, yet maintains similar chemical and physical properties, commonly noted among nitrile elastomers. The addition of the PVC resins also provide a greater pigment-carrying capacity which allow better retention of pastel and bright colors.

EPM, EPDM - Ethylene Propylene, and Ethylene Propylene Diene rubber

Ethylene propylene rubber is an elastomer prepared from ethylene and propylene monomers (ethylene propylene copolyme)). Ethylene propylene rubber has a temperature range of -50°C to +120°/150°C (-60°F to +250°/300°F), depending on the curing system.

It has a great acceptance in the sealing world because of its excellent resistance to heat, water and steam, alkali, mild acidic and oxygenated solvents, ozone, and sunlight.

These compounds also withstand the effect of brake fluids and Skydrol™ and other phosphate ester-based hydraulic fluids. EPDM compounds are not recommended for gasoline, petroleum oil and grease, and hydrocarbon environments.

Special EPDM compounds have good resistance to steam.
EPDM Sulphur cured: inexpensive material for normal use, maximum temperature of +120°C (+250°F).
EPDM Peroxide cured: for hot water, vapor, alcohols, ketones, engine coolants, organic and inorganic acids and bases. Not resistant to mineral oils. For maximum temperatures of +150°C (+300°F).

CR - Neoprene rubber Polychloroprene

Neoprene rubbers are homopolymers of chloroprene (chlorobutadiene) and were among the earliest synthetic rubbers used to produce seals. CR has good aging characteristics in ozone and weather environments, along with abrasion and flex cracking resistance. CR is not effective in aromatic and oxygenated solvent environments. Neoprene can be compounded for service temperatures of -40°C to + 110°C (-40°F to +230°F).

Most elastomers are either resistant to deterioration from exposure to petroleum based lubricants or oxygen. Neoprene is unusual in having limited resistance to both. This, combined with a broad temperature range and moderate cost, accounts for its desirability in many seal applications for refrigerants like Freon® and ammonia.

CR is resistant to refrigerants, ammonia, Freon® ( R12, R13, R21, R22, R113, R114, R115, R134A), silicone oils, water, ozone, vegetable oils, alcohols, and low-pressure oxygen. CR has a very low resistance to mineral oils.

VMQ - Silicone rubber

Silicones are a group of elastomeric materials made from silicone, oxygen, hydrogen, and carbon. Extreme temperature range and low temperature flexibility are characteristics of silicone compounds. As a group, silicones have poor tensile strength, tear resistance, and abrasion resistance.

Special compounds have been developed with exceptional heat and compression set resistance. High strength compounds have also been made, but their strength does not compare to conventional rubber. Silicones possess excellent resistance to extreme temperatures -50°C to + 232°C (-58°F to +450°F).

Some special compounds resist even higher temperatures. Retention of properties of silicone at high temperature is superior to most other elastic materials. Silicone compounds are very clean and are used in many food and medical applications because they do not impart odor or taste. Silicone compounds are not recommended for dynamic O-ring sealing applications due to relatively low tear strength and high coefficient of friction.

Silicone is resistant to hot air, ozone, UV radiation, engine and transmission oils, animal and vegetable fats and oils, and brake fluids. VMQ also has low resistance to mineral oils. Silicone can be compounded to be electrically resistant, conductive, or flame retardant.

FVMQ - Fluorosilicone

Fluorosilicone combines the good high- and low-temperature properties of silicone with limited fuel and oil resistance. Fluorosilicones provide a much wider operational temperature range than Fluorocarbon rubbers. Primary uses of fluorosilicone O-rings are in fuel systems at temperatures up to +177°C (+350°F) and in applications where the dry-heat resistance of silicone O-rings are required.

Fluorosilicone O-rings may also be exposed to petroleum based oils and/or hydro-carbon fuels. In some fuels and oils; however, the high temperature limit in the fluid list is more conservative because fluid temperatures approaching 200°C (390°F) may degrade the fluid, producing acids which attack fluorosilicone O-rings.

For low temperature applications, fluorosilicone O-rings seal at temperatures as low as -73°C (-100°F). Due to relatively low tear strength, high friction and limited abrasion resistance of these materials, they are generally recommended for static applications only.

Fluorosilicones with high tear strength are also available. Some of these compounds exhibit improved resistance to compression set. Many fluorosilicone compounds have a higher than normal shrinkage rate so production molds for fluorosilicone products are often different from molds for nitrile.

AU, EU - Polyurethane rubber

Polyurethanes (Polyester-urethane AU), (Polyether-urethane EU) exhibit outstanding mechanical and physical properties in comparison with other elastomers. Urethanes provide outstanding resistance to abrasion and tear and have the highest available tensile strength among all elastomers while providing good elongation characteristics.

Ether based urethanes (EU) are directed toward low temperature flexibility applications. The ester based urethanes (AU) provide improved abrasion, heat, and oil swell resistance.

Over a temperature range of -40°C to +82°C (-40°F to +180°F), resistance to petroleum based oils, hydrocarbon fuels, oxygen, ozone and weathering is good. However, polyurethanes quickly deteriorate when exposed to acids, ketones and chlorinated hydrocarbons.

Certain types of polyester-urethanes (AU) are also sensitive to water and humidity. Polyether-urethanes (EU) offer better resistance to water and humidity. The inherent toughness and abrasion resistance of polyurethane (EU) seals is particularly desirable in hydraulic systems where high pressures, shock loads, wide metal tolerances, or abrasive contamination is anticipated.

FKM - Fluorocarbon rubber

Fluorocarbon elastomers have grown to major importance in the seal industry. Due to its wide range of chemical compatibility, temperature range, low compression set, and excellent aging characteristics, fluorocarbon rubber is the most significant single elastomer developed in recent history. Fluorocarbon elastomers are highly fluorinated carbon-based polymers used in applications to resist harsh chemical and ozone attack.

The working temperature range is considered to be -26°C to +205°/230°C (-15°F to +400°/440°F). But for short working periods it will take even higher temperatures. Special compounds having improved chemical resistance are also available with new types always being developed.

Generally speaking, with increasing fluorine content, resistance to chemical attack is improved while low temperature characteristics are diminished. There are, however, specialty grade fluorocarbons that can provide high fluorine content with low temperature properties.

Fluorocarbon O-rings should be considered for use in aircraft, automobile and other mechanical devices requiring maximum resistance to elevated temperatures and to many fluids. FKM (FPM, Viton®, Fluorel®) resist mineral oils and greases, aliphatic, aromatic and also special chlorinated hydrocarbons, petrol, diesel fuels, silicone oils and greases. It is suitable for high vacuum applications.

Many fluorocarbon compounds have a higher than normal mold shrinkage rate, molds for fluorocarbon products are often different from molds for Nitrile.

FFKM - Perfluorocarbons

The relative inertness of fluorocarbon rubbers is provided by fluorine-carbon bonds on the elastomer backbone. Generally speaking, with increasing fluorine content, resistance to chemical attack is improved. Where fluorocarbon rubbers have a fluorine content of 63 - 68 %, the perfluorocarbons have a fluorine content of 73%.

Perfluorelastomers possess excellent resistance to extreme temperatures -26°C to +260°C (-15°F to +500°F). FFKM perfuoroelastomers: (Kalrez®) offers the best chemical resistance of all elastomers. Some types are particularly suitable for hot water, steam and hot amines. Some resist temperatures up to +326°C (+620°F).


Teflon® FEP/PFA is a copolymer of tetrafluorethylene and hexafluorpropylene. Teflon® FEP/PFA has a lower melting point than PTFE making it suitable for injection moulding. Teflon® FEP/PFA is used for encapsulation with Teflex O-rings. Teflon® FEP/PFA has a wide spectrum of chemical compatibility and temperature range and excellent aging characteristics. Maximum operating temperature for Teflon® FEP/PFA is +205°C (+400°F). A Teflon® FEP/PFA encapsulation is available for higher temperatures (260°C).

TFE/P (Aflas®) (FEPM)

TFE/P is a copolymer of tetrafluoroethylene and propylene with a fluorine content of app. 54%. This material is unique due to its resistance to petroleum products, steam, and phosphate-esters. In some respects it exhibits media compatibility properties similar to ethylene propylene and fluorocarbon.

The compression set resistance at high temperatures is inferior to standard fluorocarbons. Service temperatures are -5°C (25°F) to +204°C (+400°F). TFE/P provides improved chemical resistance to a wide spectrum of automotive fluids and additives.

It is resistant to engine oils of all types, engine coolants with high level of rust inhibitors, extreme pressure (EP) gear lubricants, transmission and power steering fluids, and all types of brake fluids including DOT 3, mineral oil, and silicone oil. TFE/P is ideal for heat transfer media, amines, acids and bases, as well as hot water and steam up to +170°C (+340°F).

There are numerous other elastomers such as ACM, CO/ECO, Vamac®, SBR, IIR and O-rings from special materials. ERIKS offers many possibilities in special O-rings compounds to improve certain properties like: Silicone free and Labs free Coatings - Encapsulated FEP and PFA - PTFE O-rings - Internal Lubrication - High Purity - Micro O-rings - Vulc-O-rings. Furthermore, ERIKS offers many compounds with homologations, like: KTW – FDA – WRC – NSF – DVGW and many more. Please contact our specialists for these requests.

What should be considered when selecting the right seal material

The primary fluids which the O-ring or Quad-Ring®/X-Ring will seal
Other fluids to which the seal will be exposed, such as cleaning fluids or lubricants
The suitability of the material for the application’s temperature extremes - hot and cold
The presence of abrasive external contaminants
Lubricating the seal and mating components with an appropriate lubricant before assembling the unit

If you don't know which size you need, our O-Ring-Calculator will help you find the right size.
If you don't know which o-ring is suitable for which industry, you will find all the information you need in the O-Ring Choosing Guide.

O-Ring-Calculator O-Ring Choosing Guide

5. Causes of o-ring damage and prevention

O-rings are available in many shapes and sizes. The O-ring that you choose should match your specific application. This prevents any unnecessary damage to your seal and avoids leaks. There are various reasons why leaks can occur in your application. Read here more in our guide about how to prevent damage to your o-rings.

6. Maintenance

Storage life is the maximum period of time, starting from the time of manufacture, that an elastomeric seal element, appropriately packaged, may be stored under specific conditions. After this period of time the O-ring is regarded as unserviceable for the purpose for which it was originally manufactured. The time of manufacture is the cure date for thermoset elastomers or the time of conversion into a finished product for the thermoplastic elastomers. Shelf life of elastomers when stored properly is especially determined by the specific compound.

NBR, SBR or BR for example have a storage life of up to 5 years.
CSM, EPDM or EPM can be stored up to 10 years.
FMK, ACM or FVQM have a storage life of up to 20 years.

The storage life of different elastomers differs according to ISO 2230, indicating an initial and an extension storage period for unassembled components.

Factors that can influence the storage life of O-rings

Temperature: Storage temperature should be below 38°C (except when higher temperatures are caused by temporary climate changes), O-ring should be stored away from direct sources of heat (such as boilers, radiators, and direct sunlight).
Humidity: If the elastomers are not stored in sealed moisture proof bags, the relative humidity should be less than 75 % (65 % with polyurethanes).
Light: Especially direct sunlight or artificial light with ultraviolet content should be avoided; it is advisable that storage room windows should be covered with a red or orange coating if there are elastomers present.
Radiation: Protection from all sources of ionizing radiation that might cause damage.
Ozone: Ozone is damaging to some elastomeric seals, equipment such as mercury vapor lamps, high voltage electrical equipment, silent electrical discharges compustion gases or organic vapor should be avoided.
Deformation: Seals should be stored away from superimposed tensile and compressive stresses or other causes of deformation. O-rings of large inside diameter shall be formed into at least three superimposed loops so as to avoid creasing or twisting. Note: It is not possible to achieve this condition by forming just two loops, three are required.
Contact with liquid and semi-solid materials: For example contact with gasoline, greases, acids, disinfectants, and cleaning fluids - these should be avoided - unless they are an integral part of the component or the manufacturer’s packaging.
Contact with metals: Certain metals and their alloys (especially copper, manganese, and iron) are known to have deleterious effects on elastomers. Protection by individual packaging is recommended.
Contact with dusting powder: Dusting powders shall only be used for the packaging of elastomeric items in order to prevent blocking or sticking. In such instances, the minimum quantity of powder to prevent adhesion shall be used.
Contact between different elastomers: Should also be avoided.
Elastomeric seals bonded to metal parts: The metal part of bonded elastomeric seals shall not come in contact with the elastomeric element of another seal. The bonded seal shall be individually packaged. Any preservative used on the metal shall be such that it will not affect the elastomeric element or the bond to such an extent that the seal will not comply with the product specification.
Stock rotation: Elastomeric seal stock should be rotated on the FIFO (First In, First Out) principle.

In general ERIKS recommends the following storage parametres:

Ambient temperature (preferably not higher than 25°C)
Dry environment and exclusion of contamination
Protection against direct sunlight
Protection against radiation
Protection against artificial light or other light sources containing UV-radiation
Protection from ozone generating electrical devices
Store part without tension (never hang O-rings!)

7. Installation

Improper O-ring installation can lead to assembly damage which causes leakage during the first pressure test. If the system does not pressurize correctly, the entire piece of equipment has to be disassembled and seals must be replaced.

Lubrication makes the installation easier
Lubricating reduces friction between the O-ring and the mating surfaces so that the O-ring can go into the groove without difficulty. It will also reduce the installation force and enable a smooth transition because the piston is inserted in the bore.
Besides making the installation easier, lubrication also protects the O-Ring from abrasion and scuffing damage while also extending the operating life of the O-ring by creating a protective barrier over its surface.
A thin film of mineral oil, grease, silicone oil, or application fluid is usually sufficient

Proper size of the O-Ring is essential
If you choose the wrong size for the O-ring for your application, it might lead to damage. This is why it is important to verify the right size of your O-ring. If you are not sure about which size you have to buy, our O-Ring Calculator will help you to find the suitable size.

Cleanliness is important for proper seal action and long O-ring life. Foreign particles in the gland may cause leakage and can damage the O-ring.

Never glue the O-rings in the groove
There is a risk for chemical attack and hardening. An alternative is to use mounting grease. One should check the chemical compatibility first.

The stretch and expansion of the inner diameter should be considered
An inner diameter stretch as installed in a groove may not be more than 5-6% because more stretch will reduce and flatten the cross section and thus reduce the squeeze.

The inner diameter expansion to reach the groove during assembly should not exceed 50%. For very small diameters, it may be necessary to exceed this limit, If so, one should allow sufficient time for the O-ring to return to its normal size before closing the gland.

Avoid installation damage by using installation tools
If you do not use the correct tools to install an O-ring, your O-ring might become damaged when it is fitted. Avoid sharp parts that may damage the O-ring. Use an O-ring assembly set when installing or removing O-rings. This way you can install your O-rings more easily and remove them without causing damage. Also be cautious to not overstretch your O-ring excessively or to twist it when fitting.

O-Ring Installation

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For personal advise and product knowledge, visit an ERIKS location near you or contact our product specialists.

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