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.
Frente a qué resisten estos sellos – NBR (sellos AS / SA / CS)
La lista siguiente muestra los productos químicos, fluidos y gases frente a los que el elemento de sellado de NBR (caucho nitrílico) de los sellos AS, SA y CS es fiablemente resistente. Una marca en una columna de temperatura indica que el sello es apto para ese medio a esa temperatura. Las celdas vacías indican que el medio no se recomienda a esa temperatura — elija un sello de mayor grado (FKM, silicona o PTFE).
Valores indicativos basados en tablas industriales (Parker O-Ring Handbook, Trelleborg, ERIKS). El usuario final es responsable de validar la idoneidad para su aplicación específica — concentración, presión, esfuerzo mecánico y tiempo de exposición importan. En caso de duda, contacte con Extreme Bearing para una recomendación a medida.
| Sustancia química | 20°C / 68°F | 60°C / 140°F | 100°C / 212°F |
|---|---|---|---|
| Formaldehyde (40%) | ✓ | ||
| Ascorbic ácido | ✓ | ✓ | |
| Citric ácido | ✓ | ✓ | |
| Ácidos grasos (>C6) | ✓ | ||
| Oxalic ácido | ✓ | ||
| Phthalic ácido | ✓ | ||
| Stearic ácido | ✓ | ✓ | |
| Tannic ácido (10%) | ✓ | ✓ | |
| Tartaric ácido | ✓ | ✓ | |
| Boric ácido | ✓ | ✓ | |
| Carbonic ácido | ✓ | ✓ | |
| Silicic ácido | ✓ | ||
| Sulfitos | ✓ | ✓ | |
| Ammonia, acuoso | ✓ | ||
| Sosa cáustica y potasa | ✓ | ||
| Lime (CaO) | ✓ | ✓ | |
| Alum | ✓ | ✓ | ✓ |
| Aluminium cloruro | ✓ | ✓ | |
| Aluminium sulfato | ✓ | ✓ | |
| amonio cloruro | ✓ | ✓ | |
| Brines, saturado | ✓ | ✓ | |
| Bromide (K) solución | ✓ | ✓ | |
| Calcium cloruro | ✓ | ✓ | |
| Chlorates of Na, K, Ba | ✓ | ✓ | |
| Chlorides of Na, K, Ba | ✓ | ✓ | ✓ |
| Copper salts (most) | ✓ | ✓ | |
| Ferric cloruro | ✓ | ✓ | |
| Ferrous sulfato | ✓ | ✓ | |
| Lead acetate | ✓ | ||
| Mercuric cloruro | ✓ | ✓ | |
| Mercury | ✓ | ✓ | ✓ |
| Nickel salts | ✓ | ✓ | |
| Nitratos de Na, K y NH3 | ✓ | ✓ | |
| nitrito (Na) | ✓ | ✓ | |
| Silver nitrato | ✓ | ✓ | |
| sodio carbonato | ✓ | ✓ | |
| sodio silicate | ✓ | ✓ | |
| sodio sulfuro | ✓ | ✓ | |
| Stannic cloruro | ✓ | ||
| Sulphates (Na, K, Mg, Ca) | ✓ | ✓ | |
| Zinc cloruro | ✓ | ✓ | |
| Cyclohexane | ✓ | ✓ | |
| Naptha | ✓ | ✓ | |
| Petroleum spirits | ✓ | ✓ | |
| Paraffin wax | ✓ | ✓ | |
| Aceites diésel | ✓ | ✓ | |
| Aceites minerales | ✓ | ✓ | |
| Aceites vegetales y animales | ✓ | ✓ | |
| Alcohols | ✓ | ||
| Methanol | ✓ | ||
| Glycerine | ✓ | ✓ | |
| Glycols | ✓ | ✓ | |
| Glycol, ethylene | ✓ | ✓ | |
| Acetylene | ✓ | ✓ | |
| Refrigerantes fluorados | ✓ | ||
| Sulphur | ✓ | ✓ | |
| Agua destilada | ✓ | ✓ | |
| Agua blanda | ✓ | ✓ | |
| Agua dura | ✓ | ✓ | |
| Agua de mar | ✓ | ✓ | |
| Aire húmedo | ✓ | ✓ | |
| Beer | ✓ | ✓ | |
| Zumos de fruta | ✓ | ✓ | |
| Gelatine | ✓ | ✓ | |
| Jugos de carne | ✓ | ✓ | |
| Milk products | ✓ | ✓ | |
| Molasses | ✓ | ✓ | |
| Starch | ✓ | ✓ | |
| Sugar, syrups & jams | ✓ | ✓ | |
| Tallow | ✓ | ✓ | |
| Urea (30%) | ✓ | ✓ | |
| Yeast | ✓ | ✓ | |
| Detergents, synthetic | ✓ | ✓ | |
| Silicone fluids | ✓ | ✓ | |
| Agentes humectantes (<5%) | ✓ | ✓ | |
| Ethanol | ✓ | ||
| Isopropanol (IPA) | ✓ | ||
| Propylene glycol | ✓ | ✓ | |
| agua/glycol coolant | ✓ | ✓ | |
| Fluido hidráulico (HL, HLP, HM, mineral) | ✓ | ✓ | |
| Fluido hidráulico HFA (aceite en agua) | ✓ | ✓ | |
| Fluido hidráulico HFC (agua-glicol) | ✓ | ✓ | |
| Líquido de frenos (DOT 3/4, glicol) | ✓ | ||
| Gasolina | ✓ | ||
| Kerosene | ✓ | ✓ | |
| Jet combustible (JP-4/JP-5/JP-8) | ✓ | ✓ | |
| combustibleóleo / combustible aceite | ✓ | ✓ | |
| LPG (propane, butane) | ✓ | ✓ | |
| AdBlue (urea solución 32.5%) | ✓ | ✓ | |
| Transformer aceite | ✓ | ✓ | |
| Turbine aceite | ✓ | ✓ | |
| Gear aceite | ✓ | ✓ | |
| Fluido de transmisión ATF | ✓ | ✓ | |
| Grasa de silicona | ✓ | ✓ | |
| Grasa de jabón de litio | ✓ | ✓ | |
| comprimido aire, seco | ✓ | ✓ | |
| Nitrogen (N2) | ✓ | ✓ | ✓ |
| Carbon dioxide (CO2) | ✓ | ✓ | |
| Hydrogen (H2) | ✓ | ✓ | |
| Helium (He) | ✓ | ✓ | ✓ |
| Argon (Ar) | ✓ | ✓ | ✓ |
| Ethylene (C2H4) | ✓ | ✓ | |
| Propylene (C3H6) | ✓ | ✓ | |
| Methane (CH4) | ✓ | ✓ | |
| gas natural | ✓ | ✓ | |
| Carbon monoxide (CO) | ✓ | ✓ | |
| Refrigerante R22 (HCFC) | ✓ | ||
| Refrigerante R134a (HFC) | ✓ | ✓ | |
| Refrigerante R1234yf (HFO) | ✓ | ✓ | |
| Refrigerante R717 (amoníaco) | ✓ | ||
| Refrigerante R744 (CO2) | ✓ | ✓ | |
| Vino | ✓ | ✓ | |
| Café / té | ✓ | ✓ | |
| Zumo vegetal | ✓ | ✓ | |
| Limpiador CIP alcalino (1-3%) | ✓ | ||
| Pentane | ✓ | ✓ | |
| Hexane | ✓ | ✓ | |
| Heptane | ✓ | ✓ | |
| Octane | ✓ | ✓ | |
| Isobutylene | ✓ | ||
| Butanol (n-butanol) | ✓ | ||
| n-Propanol | ✓ | ||
| Oleic ácido | ✓ | ||
| Palmitic ácido | ✓ | ||
| Adipic ácido | ✓ | ✓ | |
| Lauric ácido | ✓ | ||
| amonio sulfato | ✓ | ✓ | |
| amonio nitrato | ✓ | ✓ | |
| Copper sulfato | ✓ | ✓ | |
| Zinc sulfato | ✓ | ✓ | |
| Magnesium sulfato | ✓ | ✓ | |
| Magnesium cloruro | ✓ | ✓ | |
| Barium cloruro | ✓ | ✓ | |
| potasio cloruro | ✓ | ✓ | ✓ |
| sodio thiosulphate | ✓ | ✓ | |
| Refrigerante R32 (HFC) | ✓ | ✓ | |
| Refrigerante R410A (mezcla HFC) | ✓ | ✓ | |
| Refrigerante R454B (mezcla HFO) | ✓ | ✓ | |
| Refrigerante R1234ze (HFO) | ✓ | ✓ | |
| Refrigerante R290 (propano) | ✓ | ✓ | |
| Refrigerante R600a (isobutano) | ✓ | ✓ | |
| Sulphur hexafluoride (SF6) | ✓ | ✓ | |
| Nitrous oxide (N2O) | ✓ | ✓ | |
| Olive aceite | ✓ | ✓ | |
| Soybean aceite | ✓ | ✓ | |
| Palm aceite | ✓ | ✓ | |
| Rapeseed (canola) aceite | ✓ | ✓ | |
| Fish aceite | ✓ | ✓ | |
| Mantequilla | ✓ | ✓ | |
| Cheese curds / whey | ✓ | ✓ | |
| Eggs (raw / líquido) | ✓ | ✓ | |
| Mostaza | ✓ | ✓ | |
| líquido sugar / glucose syrup | ✓ | ✓ | |
| Quaternary amonio compounds (QACs) | ✓ | ||
| Chlorhexidine solución | ✓ | ✓ | |
| Aceite de corte (emulsión soluble en agua) | ✓ | ✓ | |
| Aceite de corte (puro, mineral) | ✓ | ✓ | |
| HVO renewable diésel | ✓ | ✓ | |
| Marine heavy combustible aceite (HFO) | ✓ | ||
| Lodo de perforación (base agua) | ✓ | ||
| Lodo de perforación (base aceite) | ✓ | ✓ | |
| Lechada de cemento | ✓ | ||
| Lechada de ceniza volante | ✓ | ✓ | |
| Cyanide solución (gold mining, 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.