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 and SA radial bearing shaft seals – stainless steel bearing housing

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.

AS seal grease direction illustration

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.

SA seal grease direction illustration
Dirt build-up in bearing housing seal cavity

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.

Conveyor belt in seawater environment with pillow block bearing and single-point greaser

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.

Example of damage from incorrect greasing of a pressure-tight bearing unit

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.

Contra o que estas vedações resistem – NBR (vedações AS / SA / CS)

A lista abaixo apresenta os produtos químicos, fluidos e gases contra os quais o elemento de vedação em NBR (borracha nitrílica) das vedações AS, SA e CS resiste de forma confiável. Uma marca numa coluna de temperatura indica que a vedação é adequada para esse meio a essa temperatura. As células vazias indicam que o meio não é recomendado a essa temperatura — opte então por uma vedação superior (FKM, silicone ou PTFE).

Valores indicativos baseados em tabelas industriais (Parker O-Ring Handbook, Trelleborg, ERIKS). O utilizador final é responsável por validar a adequação à sua aplicação específica — concentração, pressão, esforço mecânico e tempo de exposição importam. Em caso de dúvida, contacte a Extreme Bearing para uma recomendação personalizada.

Substância química 20°C / 68°F 60°C / 140°F 100°C / 212°F
Formaldehyde (40%)
Ascorbic ácido
Citric ácido
Ácidos gordos (>C6)
Oxalic ácido
Phthalic ácido
Stearic ácido
Tannic ácido (10%)
Tartaric ácido
Boric ácido
Carbonic ácido
Silicic ácido
Sulfitos
Ammonia, aquoso
Soda cáustica e potassa
Lime (CaO)
Alum
Aluminium cloreto
Aluminium sulfato
amónio cloreto
Brines, saturado
Bromide (K) solução
Calcium cloreto
Chlorates of Na, K, Ba
Chlorides of Na, K, Ba
Copper salts (most)
Ferric cloreto
Ferrous sulfato
Lead acetate
Mercuric cloreto
Mercury
Nickel salts
Nitratos de Na, K e NH3
nitrito (Na)
Silver nitrato
sódio carbonato
sódio silicate
sódio sulfureto
Stannic cloreto
Sulphates (Na, K, Mg, Ca)
Zinc cloreto
Cyclohexane
Naptha
Petroleum spirits
Paraffin wax
Óleos diesel
Óleos minerais
Óleos vegetais e animais
Alcohols
Methanol
Glycerine
Glycols
Glycol, ethylene
Acetylene
Refrigerantes fluorados
Sulphur
Água destilada
Água macia
Água dura
Água do mar
Moist ar
Beer
Sumos de fruta
Gelatine
Sucos de carne
Milk products
Molasses
Starch
Sugar, syrups & jams
Tallow
Urea (30%)
Yeast
Detergents, synthetic
Silicone fluids
Agentes molhantes (<5%)
Ethanol
Isopropanol (IPA)
Propylene glycol
água/glycol coolant
Fluido hidráulico (HL, HLP, HM, mineral)
Fluido hidráulico HFA (óleo em água)
Fluido hidráulico HFC (água-glicol)
Fluido de freio (DOT 3/4, glicol)
Gasolina
Kerosene
Jet combustível (JP-4/JP-5/JP-8)
óleo combustível / combustível óleo
LPG (propane, butane)
AdBlue (urea solução 32.5%)
Transformer óleo
Turbine óleo
Gear óleo
Fluido de transmissão ATF
Graxa de silicone
Graxa de sabão de lítio
comprimido ar, seco
Nitrogen (N2)
Carbon dioxide (CO2)
Hydrogen (H2)
Helium (He)
Argon (Ar)
Ethylene (C2H4)
Propylene (C3H6)
Methane (CH4)
gás natural
Carbon monoxide (CO)
Refrigerante R22 (HCFC)
Refrigerante R134a (HFC)
Refrigerante R1234yf (HFO)
Refrigerante R717 (amônia)
Refrigerante R744 (CO2)
Vinho
Café / chá
Sumo vegetal
Limpador CIP alcalino (1-3%)
Pentane
Hexane
Heptane
Octane
Isobutylene
Butanol (n-butanol)
n-Propanol
Oleic ácido
Palmitic ácido
Adipic ácido
Lauric ácido
amónio sulfato
amónio nitrato
Copper sulfato
Zinc sulfato
Magnesium sulfato
Magnesium cloreto
Barium cloreto
potássio cloreto
sódio thiosulphate
Refrigerante R32 (HFC)
Refrigerante R410A (mistura HFC)
Refrigerante R454B (mistura HFO)
Refrigerante R1234ze (HFO)
Refrigerante R290 (propano)
Refrigerante R600a (isobutano)
Sulphur hexafluoride (SF6)
Nitrous oxide (N2O)
Olive óleo
Soybean óleo
Palm óleo
Rapeseed (canola) óleo
Fish óleo
Manteiga
Cheese curds / whey
Eggs (raw / líquido)
Mostarda
líquido sugar / glucose syrup
Quaternary amónio compounds (QACs)
Chlorhexidine solução
Óleo de corte (emulsão solúvel em água)
Óleo de corte (puro, mineral)
HVO renewable diesel
Marine heavy combustível óleo (HFO)
Lama de perfuração (base água)
Lama de perfuração (base óleo)
Lama de cimento
Lama de cinza volante
Cyanide solução (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.