Radial Bearing Shaft Seals – AS and SA
AS and SA are radial oil seals for stainless steel bearing housings. They seal bearing housings against contaminants with long-lasting efficiency. There are two versions available, AS and SA. Each version has a specific design for specific applications.
The seals are made of nitrile rubber (NBR) which provides good resistance against mineral oils and greases, making them suitable for a wide range of standard industrial applications.
AS Seal
AS oil seals are designed with asymmetric lip angles. The angle α between the shaft and lip on the air side is larger than the angle β on the lubricant side. This geometry is designed to prevent contamination from entering the bearing housing while retaining lubricant inside. Normally, seals are designed with a small angle β on the lubricant side and a large angle α on the air side. This prevents lubricant from leaking out of the system. However, when grease is used, the difference in angles is less important and often reversed to provide better sealing against contaminants from outside. This is what we call the AS version.
The AS seal provides reliable sealing for bearing housings in standard to moderately contaminated environments, especially suitable for use in closed bearing assemblies such as AS / AS-VK assembly. Used on places with none abrasive surrounding. Just to close and become a maintenance free bearing unit sealed against contaminants.
Mounting tip
It is necessary that, if you do the initial greasing, to keep the cap a little bit open. To ensure that air can escape.
SA Seal
SA oil seals are designed with asymmetric lip angles as shown in the illustration. The angle α between the shaft and lip on the air side is smaller than the angle β on the lubricant side to prevent lubricant from leaking out of the system. When grease is used, the difference in angles is less important and often reversed to provide better sealing against contaminants from outside. We call this seal version SA. Leakage is less of a concern here due to the consistency of grease, which prevents excessive loss of lubricant. Therefore the main purpose of the grease seal is to keep contaminants out.
To improve bearing life by the correct use of bearing shaft seals, it is recommended to use an automatic lubricator or lubricate regularly. Only a small quantity of grease is necessary when slowly flushed into the bearing cavity to force dust and moisture away from the seal lips.
Note – SA Seal Is Not for Food Applications
The SA seal is not suitable for applications where high hygiene is demanded because the cavity in the lip can act as a chamber for collecting dirt. For high hygiene applications, use our CC design.
Not suitable for abrasive environments
The AS seal and, to a lesser extent, the SA seal are not suitable for applications where there is a risk of contamination from abrasive materials. For this type of application, use our CS design.
Grease Is a Great Help to Sealing Bearing Housings Against Contaminants
Grease can be a great help to sealing bearing housings against contaminants. The gaps between the lips of the centrifugal seal and the stator must be sealed to keep out dust and water. To improve bearing life for centrifugal bearing shaft seals, it is recommended to use an automatic lubricator or to lubricate regularly. Only a small quantity of grease is necessary when slowly flushed into the bearing cavity to force dust and moisture away from the working parts.
Examples of Grease Diagrams Using AS Bearing Shaft Seals
If the contamination is only on one side of the bearing unit, a seal combination can be chosen that is based on refilling the grease on this side. In this way, the contamination along with the grease shall flow away from the sealing lips. An example of such an assembly, a CS-AS combination, is shown in one of the illustrations with the path of the grease shown by the red arrows.



Important Information for Initial Greasing of Pressure-Tight Bearing Units
In some configurations, the bearing units from Extreme Bearing are bearing shaft seals pressure-tight. Therefore it is necessary to keep the cap a little bit open while you do the initial greasing. Otherwise problems like in the picture shown here can occur.
In addition, whenever it is necessary to add some more grease later, you should always take care not to create overpressure in the housing. The Extreme Bearing units are pressure-tight when used with the following configurations of seals: AS/AS, AS/VK, CL/CL and CL/VK.
Ce à quoi ces joints résistent – NBR (joints AS / SA / CS)
La liste ci-dessous présente les produits chimiques, fluides et gaz auxquels l’élément d’étanchéité en NBR (caoutchouc nitrile) des joints AS, SA et CS résiste de manière fiable. Une coche dans une colonne de température indique que le joint convient à ce milieu à cette température. Les cases vides signalent que le milieu n’est pas recommandé à cette température — choisissez alors un joint de qualité supérieure (FKM, silicone ou PTFE).
Valeurs indicatives basées sur des tableaux industriels (Parker O-Ring Handbook, Trelleborg, ERIKS). L’utilisateur final est responsable de la validation de l’adéquation à son application spécifique — la concentration, la pression, la sollicitation mécanique et le temps d’exposition comptent. En cas de doute, contactez Extreme Bearing pour une recommandation sur mesure.
| Substance chimique | 20°C / 68°F | 60°C / 140°F | 100°C / 212°F |
|---|---|---|---|
| Formaldehyde (40%) | ✓ | ||
| Ascorbic acide | ✓ | ✓ | |
| Citric acide | ✓ | ✓ | |
| Acides gras (>C6) | ✓ | ||
| Oxalic acide | ✓ | ||
| Phthalic acide | ✓ | ||
| Stearic acide | ✓ | ✓ | |
| Tannic acide (10%) | ✓ | ✓ | |
| Tartaric acide | ✓ | ✓ | |
| Boric acide | ✓ | ✓ | |
| Carbonic acide | ✓ | ✓ | |
| Silicic acide | ✓ | ||
| Sulfites | ✓ | ✓ | |
| Ammonia, aqueux | ✓ | ||
| Soude caustique et potasse | ✓ | ||
| Lime (CaO) | ✓ | ✓ | |
| Alum | ✓ | ✓ | ✓ |
| Aluminium chlorure | ✓ | ✓ | |
| Aluminium sulfate | ✓ | ✓ | |
| ammonium chlorure | ✓ | ✓ | |
| Brines, saturé | ✓ | ✓ | |
| Solution de bromure (K) | ✓ | ✓ | |
| Calcium chlorure | ✓ | ✓ | |
| Chlorates of Na, K, Ba | ✓ | ✓ | |
| Chlorides of Na, K, Ba | ✓ | ✓ | ✓ |
| Copper salts (most) | ✓ | ✓ | |
| Ferric chlorure | ✓ | ✓ | |
| Ferrous sulfate | ✓ | ✓ | |
| Lead acetate | ✓ | ||
| Mercuric chlorure | ✓ | ✓ | |
| Mercury | ✓ | ✓ | ✓ |
| Nickel salts | ✓ | ✓ | |
| Nitrates de Na, K et NH3 | ✓ | ✓ | |
| nitrite (Na) | ✓ | ✓ | |
| Silver nitrate | ✓ | ✓ | |
| sodium carbonate | ✓ | ✓ | |
| sodium silicate | ✓ | ✓ | |
| sodium sulfure | ✓ | ✓ | |
| Stannic chlorure | ✓ | ||
| Sulphates (Na, K, Mg, Ca) | ✓ | ✓ | |
| Zinc chlorure | ✓ | ✓ | |
| Cyclohexane | ✓ | ✓ | |
| Naptha | ✓ | ✓ | |
| Petroleum spirits | ✓ | ✓ | |
| Paraffin wax | ✓ | ✓ | |
| Huiles diesel | ✓ | ✓ | |
| Huiles minérales | ✓ | ✓ | |
| Huiles végétales et animales | ✓ | ✓ | |
| Alcohols | ✓ | ||
| Methanol | ✓ | ||
| Glycerine | ✓ | ✓ | |
| Glycols | ✓ | ✓ | |
| Glycol, ethylene | ✓ | ✓ | |
| Acétylène | ✓ | ✓ | |
| Fluides frigorigènes fluorés | ✓ | ||
| Soufre | ✓ | ✓ | |
| Eau distillée | ✓ | ✓ | |
| Eau douce | ✓ | ✓ | |
| Eau dure | ✓ | ✓ | |
| Eau de mer | ✓ | ✓ | |
| Air humide | ✓ | ✓ | |
| Bière | ✓ | ✓ | |
| Jus de fruits | ✓ | ✓ | |
| Gelatine | ✓ | ✓ | |
| Jus de viande | ✓ | ✓ | |
| Produits laitiers | ✓ | ✓ | |
| Molasses | ✓ | ✓ | |
| Amidon | ✓ | ✓ | |
| Sugar, syrups & jams | ✓ | ✓ | |
| Suif | ✓ | ✓ | |
| Urea (30%) | ✓ | ✓ | |
| Levure | ✓ | ✓ | |
| Detergents, synthetic | ✓ | ✓ | |
| Silicone fluids | ✓ | ✓ | |
| Agents mouillants (<5%) | ✓ | ✓ | |
| Ethanol | ✓ | ||
| Isopropanol (IPA) | ✓ | ||
| Propylene glycol | ✓ | ✓ | |
| eau/glycol coolant | ✓ | ✓ | |
| Fluide hydraulique (HL, HLP, HM, minéral) | ✓ | ✓ | |
| Fluide hydraulique HFA (huile dans eau) | ✓ | ✓ | |
| Fluide hydraulique HFC (eau-glycol) | ✓ | ✓ | |
| Liquide de frein (DOT 3/4, glycol) | ✓ | ||
| essence / petrol | ✓ | ||
| Kerosene | ✓ | ✓ | |
| Jet carburant (JP-4/JP-5/JP-8) | ✓ | ✓ | |
| fioul / carburant huile | ✓ | ✓ | |
| LPG (propane, butane) | ✓ | ✓ | |
| AdBlue (solution d’urée 32,5%) | ✓ | ✓ | |
| Transformer huile | ✓ | ✓ | |
| Turbine huile | ✓ | ✓ | |
| Gear huile | ✓ | ✓ | |
| Fluide de transmission ATF | ✓ | ✓ | |
| Graisse silicone | ✓ | ✓ | |
| Graisse au savon de lithium | ✓ | ✓ | |
| comprimé air, sec | ✓ | ✓ | |
| Nitrogen (N2) | ✓ | ✓ | ✓ |
| Carbon dioxide (CO2) | ✓ | ✓ | |
| Hydrogen (H2) | ✓ | ✓ | |
| Helium (He) | ✓ | ✓ | ✓ |
| Argon (Ar) | ✓ | ✓ | ✓ |
| Ethylene (C2H4) | ✓ | ✓ | |
| Propylene (C3H6) | ✓ | ✓ | |
| Methane (CH4) | ✓ | ✓ | |
| Gaz naturel | ✓ | ✓ | |
| Carbon monoxide (CO) | ✓ | ✓ | |
| Fluide frigorigène R22 (HCFC) | ✓ | ||
| Fluide frigorigène R134a (HFC) | ✓ | ✓ | |
| Fluide frigorigène R1234yf (HFO) | ✓ | ✓ | |
| Fluide frigorigène R717 (ammoniac) | ✓ | ||
| Fluide frigorigène R744 (CO2) | ✓ | ✓ | |
| Vin | ✓ | ✓ | |
| Café / thé | ✓ | ✓ | |
| Jus de légumes | ✓ | ✓ | |
| Nettoyant CIP alcalin (1-3%) | ✓ | ||
| Pentane | ✓ | ✓ | |
| Hexane | ✓ | ✓ | |
| Heptane | ✓ | ✓ | |
| Octane | ✓ | ✓ | |
| Isobutylene | ✓ | ||
| Butanol (n-butanol) | ✓ | ||
| n-Propanol | ✓ | ||
| Oleic acide | ✓ | ||
| Palmitic acide | ✓ | ||
| Adipic acide | ✓ | ✓ | |
| Lauric acide | ✓ | ||
| ammonium sulfate | ✓ | ✓ | |
| ammonium nitrate | ✓ | ✓ | |
| Copper sulfate | ✓ | ✓ | |
| Zinc sulfate | ✓ | ✓ | |
| Magnesium sulfate | ✓ | ✓ | |
| Magnesium chlorure | ✓ | ✓ | |
| Barium chlorure | ✓ | ✓ | |
| potassium chlorure | ✓ | ✓ | ✓ |
| sodium thiosulphate | ✓ | ✓ | |
| Fluide frigorigène R32 (HFC) | ✓ | ✓ | |
| Fluide frigorigène R410A (mélange HFC) | ✓ | ✓ | |
| Fluide frigorigène R454B (mélange HFO) | ✓ | ✓ | |
| Fluide frigorigène R1234ze (HFO) | ✓ | ✓ | |
| Fluide frigorigène R290 (propane) | ✓ | ✓ | |
| Fluide frigorigène R600a (isobutane) | ✓ | ✓ | |
| Hexafluorure de soufre (SF6) | ✓ | ✓ | |
| Nitrous oxide (N2O) | ✓ | ✓ | |
| Olive huile | ✓ | ✓ | |
| Soybean huile | ✓ | ✓ | |
| Palm huile | ✓ | ✓ | |
| Rapeseed (canola) huile | ✓ | ✓ | |
| Fish huile | ✓ | ✓ | |
| Beurre | ✓ | ✓ | |
| Cheese curds / whey | ✓ | ✓ | |
| Œufs (crus / liquides) | ✓ | ✓ | |
| Moutarde | ✓ | ✓ | |
| liquide sugar / glucose syrup | ✓ | ✓ | |
| Quaternary ammonium compounds (QACs) | ✓ | ||
| Solution de chlorhexidine | ✓ | ✓ | |
| Cutting huile (eau-soluble emulsion) | ✓ | ✓ | |
| Cutting huile (neat, minérale) | ✓ | ✓ | |
| HVO renewable diesel | ✓ | ✓ | |
| Marine heavy carburant huile (HFO) | ✓ | ||
| Boue de forage (base eau) | ✓ | ||
| Boue de forage (base huile) | ✓ | ✓ | |
| Coulis de ciment | ✓ | ||
| Coulis de cendres volantes | ✓ | ✓ | |
| Solution de cyanure (extraction aurifère, NaCN) | ✓ |
Service instruction
Please inform your maintenance crew about this special service operating instruction. It could be helpful to dismount the grease nipples and exchange them with a standard stainless screw, so it will be impossible to make mistakes.