Oil seals are rotary shaft seals that close a gap between stationary and moving components and prevent lubricant to escape and thus stop contamination through the clearance. There are different types of oil seals that fit a different application and surroundings and are made out of different materials. The right material and type of oil seal is determined by the application and the medium that will be used with the oil seal.
The DIN 3760 standard specifies dimensions and requirements for materials, marking, use and installation of rotary shaft lip seals used for retaining fluid or grease in unpressurized equipment, or equipment with a low differential pressure, that has rotating shafts. DIN 3761 defines standards for rotary shaft lip type seals for automobiles.
In the following table you will find the most important norm designs of oil seals according to the DIN standard and their corresponding ERIKS oil seal product.
DIN Standard 3760/3761 ERIKS A rubber covered R AS as type A with dust lip RS B metal cased design M BS as type B with dust lip MS C double metal cased GV CS as type C with dust lip GVST
The standard oil seal consists of a metal ring as the inner skeleton which provides the structural stability to the oil seal. The outer part is made of rubber or metal - based on the requirement and the application of the oil seal. The spring on the lip of the oil seal provides support to the lip and prevents the lubricant from leaking outside and also prevents contaminants from entering.
The oil seal consists of a metal ring as the inner skeleton which provides the structural stability to the oil seal. The outer part is made of rubber or metal - based on the requirement and the application of the oil seal. The spring on the lip of the oil seal provides support to the lip and prevents the lubricant from leaking outside and also prevents contaminants from entering.
When present, the dust lip (which can be seen on the left oil seal in the picture) works to protect the sealing lip while blocking dust and dirt from entering the system, ensuring longer seal lifetime. Dust lips are located on the inner diameter of the oil seal. An oilseal with dust lip may also be called a double lip oilseal.
Tip for greasing oil seals with dust lips: If oil seals with fixed dust lips are being used, the space between the sealing lip and the dust lip may also be filled entirely with grease. The medium to be sealed will dissipate the heat.
A garter spring is a coiled steel spring that is connected at each end to create a circular shape. It maintains the radial force exerted by the sealing lip around the shaft surface.
Wide range of oil seals
Explore the full range of oil seals in the ERIKS webshop and find the right product for your application.
See the range
The most commonly used oil seals in most applications are rubber cased or metal cased oil seals. In the following chapter we will give an overview over the most important oil seals and their applications and specifications.
Metal-cased oil seals are used when installed to a housing bore made of the same material. This allows for equal contraction and expansion of the materials during operation, preventing leakage from occurring. Typically metal-cased seals are more cost efficient than rubber seals.
Rubber-cased oil seals are the most common oil seal execution, used when a metal-cased seal has the potential to fail (for example because of thermal expansion). Oil seals with a rubber case cannot rust, in contrast to oil seals with metal cases. Moreover, oil seals with a rubber case can seal a lightly damaged housing much better than metal cased oils seals. In high temperatures and high pressures, fast expanding rubber can provide a tight fit and more stable sealability.
The most commonly used type is type R. This type has a carbon steel insert and has rubber outside diameter. The rubber gives a good sealing capability, even when the housing is not fully in tolerance. The sealing lip with spring provides interference on the shaft for effective sealing. The outside diameter, with inner metal reinforcement case, allows press-fitting in the housing, with sufficient interference on the rubber to provide static sealing.
The sealing element is produced from a high performance Nitrile rubber. This in combination with a high quality galvanised steel garter spring gives the ERIKS Oil Seal an optimum life. In order to prevent leakages due to a hydrodynamic pumping effect is it necessary that the sealing lip contact area on the sleeve or shaft is without any traces of machine lay.
Here is an overview of other commonly used oil seals with an outside rubber surface:
Picture ERIKS type Description Find your oil seal R Rubber outer diameter with a carbon steel insert. Construction is in accordance with DIN 3760A (Category A) and available in both metric and inch sizes. View all R oil seals R DUO R type with two sealing lips, used for sealing two separate media. When the requested R-Duo type is not available, two R-types can be fitted back to back. View all R DUO oil seals RST Oil Seal with additional dust lip to prevent damage of sealing lip and to avoid the ingress of dust, dirt, water etc. into the system. Very commonly used in both metric and inch sizes View all RST oil seals RST D Seals pressures to 10 bar (1MPa) depending on the circumstances because it is more compact than type RST. It is recommended that our application engineers should be contacted. View all RST D oil seals GR Viton covered seal with completely encapsulated steel insert for high temperature and chemically aggressive applications; it is supplied with a stainless steel spring as standard. The Viton® used in the manufacture of Oil Seals is produced by DuPont Performance Elastomers. View all GR oil seals GRST Similar to Viton GR, but with an additional dust lip to prevent damage to the sealing lip and to prevent ingress of dust into the system. It is supplied with a stainless steel spring as standard. View all GRST oil seals RZV Smaller sizes only for applications such as needle bearings and grease seal. View all RZV oil seals
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We understand that every application is different and that every project is a fresh challenge. That is why our product specialists are at hand to provide you with personal advice and in-depth product knowledge.
Call us on +32 (0)3 829 27 32 | Email us on seals@eriks.be.
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Are you looking to keep your machinery free from any unwanted leakages but aren’t sure which rotary shaft seal is right for your needs? This guide will provide you with everything you need to know in order to select the right one for your application.
Oil seals, which are also known as rotary shaft seals, fluid seals or grease seals, play an important role in closing down the gaps between moving and stationary elements of mechanical equipment.
By preventing lubricants from escaping, they protect key components of machinery from being damaged by leaks of various fluids. Everything from car engines to assembly machines use these oil seals to remain free from any harmful interactions that can cause serious and expensive damage to any of their critical parts.
There are a wide range of oil seals to select from for any number of uses, so this guide will break down the most common seals to help you choose the right one for whatever piece of machinery you are working on.
What are rotary shaft seals?
Rotary shaft or oil seals are placed between moving and stationary pieces of machinery to ensure that contaminants, moisture, corrosive materials and abrasives do not damage the various components. They can also prevent unwanted mixing of fluids, including water and oil combining within a machine.
How are Oil Seals made?
First, an elastomer, most often nitrile, is vulcanised to a metal ring. This creates a stiffening effect that includes a specialised metal tension spring directly behind the sealing lip, keeping the oil seal firmly in place against the moving part.
Oil Seal Materials
There are many different materials used to manufacture oil seals.
Leather Oil Seals – Leather Seals, also known as Type L Oil Seals, are most common in components that are subject to dirt and poor lubrication. Since they come pre-lubricated and are able to absorb fluids, leather oil seals are able to provide sealing properties in conditions that synthetic rubber is unable to.
Synthetic Rubber Oil Seals – Styrene Butadiene Rubber oil seals, or just SBR oil seals, offer strong resistance to abrasions and lesions, making them an ideal seal for fast-moving machinery. With the ability to withstand extreme temperatures with its heat-aging qualities, they can be used in outdoor components. They are also seen as more cost-effective oil seals than natural rubber.
Nitrile Oil Seals – Nitrile oil seals, which is the commonly used term for acrylonitrile-butadiene rubber seals, is a very good general-purpose option due to the flexibility of use across a variety of components. The resistance is strong against fats, hot water, gasoline, mineral oils, grease and animal oils, making them the most often-used oil seals. They do not have a wide temperature range, making them a poor choice for machinery that can see extreme changes in temperature.
Viton Oil Seals – A synthetic rubber and fluoropolymer elastomer, Viton is used to make oil seals that provide resistance in both high temperature, up to 250°C and low compression set components. They also offer a high resistance to chemicals and abrasions, so they can be used in elements that regularly interact with petroleum and solvents.
Polyacrylate Oil Seals – Mostly selected for automotive and transmission uses, polyacrylate seals are able to withstand fuel, oil, ozone, sunlight and weather when used. With cars exposed to all these different fluids and elements, they are the perfect choice. However, they should not be used in low temperatures, as their flexibility weakens when cold.
Silicone Oil Seals – Designed to absorb lubricants in order to lessen wear and friction, silicone rotary shafts also offer high thermal resistance and a large temperature range. But, they do not handle abrasions well or interact with oxidized oils.
PTFE Oil Seals – A relatively new and exciting oil seal, the use of polytetrafluoroethylene means that they can withstand dry or unlubricated operations. With a massive thermal range of -130ºC to +200ºC and a strong resistance to chemicals, they are considered to be the future of rotary shaft seals.
How to Choose the Right Oil Seal
There are several key factors to consider when you are selecting the oil seals for your next project to ensure that you protect your machinery from immediate and long-term damage.
Pressure – Many oil seals can only withstand low-pressure applications, so understanding the compression set of your components is key.
Temperature – Just like pressure, the temperature that your oil seal will be operating in must be known so that you can choose one that can withstand the heat or cold. PTFE have the widest range of temperature, making them useful for machines who can see usage in extreme weather or elements.
Shaft Speed – Considering the speed that the shaft will be moving, the runout, the housing bore and the type of oil being sealed is vital to making sure you select an oil seal that will not suffer from abrasions or spiralling.
Fluid Types – Various oil seals are able to withstand interactions with oils, fuels, grease, water and more. Knowing what type of fluid the rotary shaft seal will be in constant contact with will ensure the longevity of the seal and surrounding components.
Lubricant Amount – Seals will always perform best when lubricated, however in some machines there are more likely to be dry spells. For these cases, selecting a leather or PTFE seal will be beneficial, as both can operate with less lubrication than others.
can be difficult to get right, especially if you do not have the original machine specifications. Thankfully, there are a few ways to identify oil seals; from their design, size and material. As there are hundreds of different oil seals available on the market, this guide will cover the four most common design types. Typically available with either a single or double lip, in Nitrile or Viton Rubber Material.
Firstly, the oil seals covered in this guide classify the single lip as the inner diameter at the bottom of the component. The single lip is vital to the function of the seal by containing the oil, grease or lubricant. The only difference between a single and double lip is the additional rubber lip on the top of the oil seal which helps prevent dust or dirt from coming close to the shaft. Identifying the oil seal lip can be misinterpreted with a visual inspection alone. For or this reason, you should press along the inner diameter at the top of the seal, if you feel a ridge with a slight movement or give it is highly likely you have a double-lipped oil seal.
Industry retailers use unique codes to identify oil seals worldwide. The most common lip style designations are 21 (single lip) and 23 (double lip), please read our Oil Seal Cross Reference Guide for more detailed information.
Fully covered outer diameter for excellent sealing. This oil seal is fully enclosed in a rubber material and is the most widely used type of oil seal. Great resistance to thermal cycling, temperatures and different chemical resistance.
Economic metal outer diameter for standard applications. This is an economical oil seal where the metal is exposed on one side and offers a closer fitting between the oil seal and housing or bore. Due to this, it has limited use with sealing thin liquids or gases.
The same design as type B with an additional inner case for greater structural rigidity. This type of oil seal is typically used in heavy-duty engineering machinery or large diameter sized seals
The same design as type A with corrosion protected metal case and stainless-steel garter spring. Suitable for use with a wide range of fuels and chemicals.
Nitrile or NBR is black in color, whereas, Viton or FKM is usually a brownish color. To understand the main comparisons between the two compounds read our Nitrile vs. Viton article.
Finally, Polymax part codes follow the same pattern as our O-rings – inner diameter, outer diameter, and height. This is different from the industry-standard convention, whereby imperial oil seals follow – outer diameter, inner diameter, and height.
We hope the information in this article helps you identify the correct oil seal for your application. If you have any queries feel free to call us.
Oil seals (also known as rotary seals or shaft seals) cover a wide range of applications ranging from domestic equipments to automotive and power plant machinery, industrial pumps, gas and aircraft turbines and compressors.
If yours is a modern system, the surface speed can go up to 30 m/s and operating temperature can be as high as 250 degree Celcius. For these type of oil seals, our general purpose high performance oil seals can be employed. When the speed is increased up to 90 m/s, the lip will be produced using PTFE based compound to reduce heat generation. For high pressure applications, we offer a wide range of oil seal profile made using PTFE based compounds.
Here at Advanced Sealing Devices, we make and design reliable oil seals for your demanding tasks. If the oil seal is not selected properly, then even a few percents of leakage can be inconvenient and incur expenses to a large number of users, as well as cause environmental pollution. Note that the oil seal is not only to seal lubricating oil, it can also be used to seal other fluids such as water, foodstuff and chemicals. We understand that the reliability and reputation of your system depends on the well functioning of these oil seals.
Standard oil seals operate in a splash environment with no pressure or little pressure as low as 0.3 – 0.5 bars. If you have a higher pressure requirement, contact us and we can provide you with a different type of oil seal design. If a standard type of oil seal is used in a high pressure situation, lip distortion and wear will occur. This will shorten the lifespan of the oil seal and create unnecessary downtime. If your housing tolerances are not controlled as closely as standard housings, we can make the outer casing of oil seals with special profile so that the oil seals can seat properly in your housing before the assembly press tool is removed.
If you application is such that the lubricating liquid is not continuously available, or the operating temperature, fluid compatibility, the speed and pressure are of a more demanding nature, then we can make oil seals using stainless steel outer casings with various pure and filled PTFE lips (type ASD SS-PTFE). This type of oil seal is now widely used by our customers in the automotive and transmissions industry. A stainless steel casing with a PTFE lip oil seal will support more highly rated machinery and allow longer oil change intervals. Our ASD SS-PTFE type is particularly suitable for dry running application, for example, an engine may run dry for some period during startup until oil splash is available especially after a long period of storage or transportation. There are certain design aspects that are required in your system before using our ASD SS-PTFE type oil seal; contact us and we will advise you on this aspect. The following are some examples of stainless steel oil seals we make for our customers.
Beside oil seals, we can also make sealing devices which seal on the radial face of your system, as opposed to the axial face for oil seals. With this type of seals, your shaft surface finish can be less critical and the seals can operate with minor runout and misalignment.
In making oil seals, we employ modern polymeric seal materials and we rely on our good understanding of the sealing mechanism that occur at the sealing interface. We will thus provide you with reliable oil seals and also to enhance protection of the environment. We offer the following types of oil seals:
General Purpose High Performance Oil Seal
Rubber Fabric Oil Seal
Rotary V-Seal
PTFE O-Ring Energised Oil Seal
PTFE Metal Case Oil Seal
PTFE Spring Energised Oil Seal
PTFE Lip Oil Seal
Type
Code
Description
Applications
Speed (m/s)
Pressure (bar)
SAA
Metal casing and reinforced inner ring, sealing lip with garter spring
dust free application
30
0.5
SAB
Metal casing, sealing lip with garter spring
dust free application
30
0.5
SAC
Rubber casing and metal insert, sealing lip with garter spring
dust free application
30
0.5
TAA
Metal casing and reinforced inner ring, additional dust lip and sealing lip with garter spring
dusty application
30
0.5
TAB
Metal casing, additional dust lip and sealing lip with garter spring
dusty application
30
0.5
TAC
Rubber casing and metal insert, additional dust lip and sealing lip with garter spring
dusty application
30
0.5
KAA
Metal casing and reinforced inner ring, additional dust lip and rubber sealing lip
oil or dust seal, for dusty application
10
-
KAB
Metal casing, additional dust lip and rubber sealing lip
oil or dust seal, for dusty application
10
-
KAC
Rubber casing and metal insert, additional dust lip and sealing lip
oil or dust seal, for dusty application
10
-
VAA
Metal casing and reinforced inner ring, rubber sealing lip
oil or dust seal
10
-
VAB
Metal casing, and rubber sealing lip
oil or dust seal
10
-
VAC Rubber casing and metal insert, sealing lip oil or dust seal 10 - HATC-R Metal casing, sealing lip with garter spring and hydrodynamic rib, right rotation engines or transmissions 30 0.5 HATC-L Metal casing, sealing lip with garter spring and hydrodynamic rib, left rotation engines or transmissions 30 0.5 ACN Metal casing and reinforced inner ring, additional dust lip and sealing lip with garter spring; high pressure application 15 10 DAC Rubber casing, metal insert, and double sealing lips in opposite direction separating two types of oils 10 0.3 DAB Metal casing, and double sealing lips in opposite direction separating two types of oils 10 0.3 SACY Seal is fixed by clamping the flange, low friction reciprocating motion, for hydraulic control valves 10 6 SACJY With nylon backup ring for high pressure reciprocating motion with large shaft misalignment 10 6 TAC4 Rubber casing with metal insert reciprocating motion, designed to minimise lip deformation 1.5 0.3 TAB4 Metal casing reciprocating motion, designed to minimise lip deformation 1.5 0.3
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Type
Code
Description
Speed (m/s)
Pressure (bar)
RFS
Rubber fabric with spring sealing lip
15
0.5
RFSD
Rubber fabric with spring sealing lip and additional dust lip
12
0.5
RFSH
Heavy-duty steel mill roll neck bearing seal with steel band
15
5.0
RFSSP
Rubber fabric with spring sealing lip (split design)
12
0.5
RF
Rubber fabric with springless sealing lip
2
0.5
RFD
Rubber fabric with double springless sealing lip
12
0.5
RFWRR
Rubber fabric rod wiper for rotary and reciprocating applications
2
0.5
RF0S
Rubber fabric with outside spring sealing lip
5
0.5
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Type
Code
Description
Speed (m/s)
Pressure (bar)
RS6
Most common profile, with sizes up to 2 metres, for gearboxes, electric motors and drives
10
-
RS6A
Compact v-seals, used in confined spaces
10
-
RS6B
Heavy-duty v-seals, for rolling mills
10
-
RS6C
Heavy-duty v-seals, for rolling mills, papermaking and large machine
10
-
RS6D
Heavy-duty v-seals, unique profiles to accommodate radial and axial support, for metals and paper mills
10
-
RS7
Wide body and tapered heel to hold ring on shaft firmly, for agricultural and automotive applications
10
-
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Type
Code
Description
Speed (m/s)
Pressure (bar)
RS10
PTFE sealing ring with preloading elastomeric o-ring element - for internal rotation
2
300
RS11
PTFE sealing ring with preloading elastomeric o-ring element - for external rotation
2
300
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Type
Code
Description
Speed (m/s)
Pressure (bar)
TSM
Metal casing with machined PTFE sealing lip
30
20
TSF
Metal casing with formed PTFE sealing lip
25
15
TSFD
Metal casing with formed PTFE sealing lip and additional PTFE dust lip
30
10
TSF2
Metal casing with double formed PTFE sealing lip
25
20
TSF2D
Metal casing with double formed PTFE sealing lip and additional PTFE dust lip
25
20
TSMS
Metal casing with machined PTFE sealing lip and garter spring
10
10
TSMSD
Metal casing with machined PTFE sealing lip and garter spring and additional PTFE dust lip
10
10
TSM2S
Metal casing with double machined PTFE sealing lip and garter spring
10
10
TSM2SD
Metal casing with double machined PTFE sealing lip and garter spring and additional PTFE dust lip
20
10
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Type
Code
Description
Speed (m/s)
Pressure (bar)
TUcRT
Reduce friction; O-ring in OD, ID lip chamfered, canted-coil spring
5
210
TUvRT
Good sealing; O-ring in OD, ID lip chamfered, cantilever spring
5
210
TUcRR
Reduce friction; O-ring in OD of heel, ID chamfered, canted-coil spring
5
70
TUvRR
Good sealing; O-ring in OD of heel, ID chamfered, cantilever spring
5
70
TUcL
Reduce friction; OD flanged, ID chamfered, canted-coil spring
5
210
TUvL
Good sealing; OD flanged, ID chamfered, cantilever spring
5
210
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Type
Code
Description
Speed (m/s)
Pressure (bar)
TC1RT
Sealing Lip (formed) with O-ring in OD
10
4
TC1SRT
Spring Energised Sealing Lip (formed) with O-ring in OD
25
4
TC2RT
Sealing Lip (machined) with O-ring in OD
30
2
TC1DRT
Sealing Lip (machined) with Dust Lip and O-ring in OD
25
4
TC3RT
Double Sealing Lip (formed) with O-ring in OD
25
10
TC3DRT
Sealing Lip (formed) with Dust Lip and O-ring in OD
25
10
If you have any questions on Agricultural Oil Seal. We will give the professional answers to your questions.