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2.5x2.87x0.18 inch Nitrile Rubber Single Lip Rotary Shaft Oil Seal R21 / SC
Equivalent to: 2.5x2.87x0.18_SC
Chemical Resistance Table [Click Here]
£7.62
ex VAT
Price Breaks
| Quantity | Prices |
|---|---|
| 10+ | £6.78 each |
| 19+ | £6.40 each |
| 29+ | £6.32 each |
| 39+ | £6.25 each |
| 49+ | £6.17 each |
| 74+ | £6.09 each |
| 99+ | £5.71 each |
In Stock
| Shaft Size not Inside Diameter (d) | = | 63.5mm = 2.5 (2-1/2) inch |
| Outside Diameter (D) | = | 72.9mm = 2.87 inch |
| Width (b) | = | 4.57mm = 0.18 inch |
Cross section of an R21 / SC style oil seal. This is a single sealing lip seal arrangement. 
An oil seal normally consists of three basic components: The Sealing Element (the nitrile rubber part), the Metal Case, and the Spring. It is a widely used sealing component. The function of a seal is to prevent the leakage of medium along the moving parts. This is mainly achieved by the sealing element. Nitrile Rubber (NBR)
NBR is the most commonly used seal material. It has good heat resistance properties, good resistance to oils, salt solutions, hydraulic oils, and gasoline. Operation temperatures are recommended from -40deg C to 120deg C. It also functions well under dry environment, but only for intermittent periods.
Construction
The seal cases are made from SAE 1008-1010 Carbon Steel and are often coated in a very thin layer of Nitrile rubber to assist sealing in the housing.
The principle function of the metal case is to impart rigidity and strength to the seal.
The spring is made from SAE 1050-1095 Carbon Spring Steel which has a protective zinc coating.
The principle function of the spring is to maintain an even gripping pressure around the shaft 
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