Oil Seals and Rotary Shaft Seals
Give us the shaft, bore and width, and the duty. We will supply the right seal, in the right material, from stock where we hold it.
An oil seal is the cheapest part in the machine and the one that stops the whole thing when it fails. It keeps lubricant where it belongs and keeps water, dust and process debris out of your bearings. Fit the wrong material or the wrong lip design and you are back at the same gearbox in a fortnight.
We supply metric and imperial rotary shaft seals across pumps, gearboxes, agitators, mixers, fans, conveyors and hydraulic equipment, and we will tell you when the leak is the shaft rather than the seal.
Types We Supply
Single lip, spring energised
The standard lubricant retention seal for clean, enclosed housings.
Double lip
Adds a dust lip to exclude water, dust and abrasives on exposed or washdown duties.
Metal cased and rubber covered
Metal outer for rigid bores, rubber covered outer for worn or split housings.
PTFE lip seals
High speed, dry running and aggressive chemistry where elastomers will not survive.
Heavy duty and split profiles
Large diameter shafts and installations where the shaft cannot be withdrawn.
Bonded seals and V rings
Static and axial exclusion parts that usually go missing from the same order.
Material Selection
| Material | Typical temperature | Best suited to |
|---|---|---|
| Nitrile (NBR) | -30C to 100C | Mineral oils, greases, water, general industrial duty |
| FKM (Viton™ type) | -20C to 200C | Synthetic oils, higher temperatures, many chemicals |
| Silicone (VMQ) | -50C to 180C | Low temperature starts and dry heat |
| PTFE | -50C to 200C | Dry running, high surface speed, aggressive chemistry |
| Polyacrylate (ACM) | -20C to 150C | Hot engine and transmission oils |
Temperature ranges are typical guidance. Actual limits depend on the fluid, the surface speed and the pressure at the lip. Send us the duty and we will confirm.
What We Need to Quote
- Shaft diameter, housing bore diameter and seal width, in that order, for example 40 x 62 x 8
- The fluid being sealed and the operating temperature
- Shaft speed in rpm, and whether the shaft is hardened and ground
- Single lip or double lip, and whether the housing is exposed to washdown or dust
- Any part number stamped on the old seal, or a photograph of it
- Quantity and how urgently you need it on site
Common sizes despatch same day when your order is placed before 2pm, with UK wide delivery and international despatch through our partner network.
Why Oil Seals Leak Again After Replacement
The shaft is grooved
A worn seal cuts a track into the shaft. A new lip cannot bridge it. Either repair the shaft, or fit the replacement at a different axial position so the lip runs on unworn metal.
Runout and misalignment
Bearing wear lets the shaft orbit. The lip cannot follow it, so it lifts once per revolution and weeps. Check the bearings before you blame the seal.
Pressure in the housing
A blocked breather turns a 0.3 bar seal into a pressure seal. It will push the lip out and leak every time.
Fitting damage
Passing the lip over a keyway, spline or sharp shaft end without a fitting sleeve nicks it invisibly. It leaks within hours.
Wrong material for the chemistry
Nitrile in hot synthetic oil hardens and cracks. It will run for weeks, then fail suddenly.
If the same seal keeps failing, that is a specification or condition problem, not a supply problem. Read our seal troubleshooting guide or failure analysis articles.
Oil Seal Questions and Answers
What is an oil seal?
An oil seal, also called a rotary shaft seal or radial lip seal, keeps lubricant inside a bearing housing, gearbox or pump and keeps dirt, water and process contamination out. A flexible sealing lip runs directly on the shaft and a garter spring holds that lip against the shaft as it wears.
How do I measure an oil seal?
Three dimensions define almost every oil seal: shaft diameter, housing bore diameter and seal width. They are quoted in that order, so a 40 x 62 x 8 seal fits a 40mm shaft in a 62mm bore and is 8mm wide. Measure the shaft and the bore rather than the worn seal itself, because used seals distort.
Which material should I specify?
Nitrile suits general mineral oil and grease duties up to around 100C. FKM handles higher temperatures, synthetic oils and more aggressive chemistry to around 200C. PTFE runs dry, handles high surface speeds and copes with chemistry that destroys elastomers. Silicone suits low temperature and dry heat. Chemistry, temperature and shaft speed decide the answer, not price.
What is the difference between a single lip and a double lip seal?
A single lip seal retains lubricant. A double lip seal adds an outer dust lip that excludes water, dust and abrasives, which is what you want on agitators, conveyor drives, mixers and anything working outdoors or in washdown.
Why does my new oil seal keep leaking?
In most cases the seal is not the problem. A grooved or scored shaft, shaft runout, a blocked breather building crankcase pressure, bearing wear, or fitting the seal without protecting the lip over a keyway or spline will all leak a brand new seal within hours. Diagnose the shaft and the housing before you fit another seal.
Can an oil seal replace a mechanical seal?
Not on process duty. Oil seals are designed for lubricant retention at low pressure, typically below 0.5 bar. Pumped process fluid under pressure needs a mechanical seal. If you are unsure which one your equipment needs, send us the duty details and we will tell you straight.
Can you supply obsolete or non standard oil seals?
Yes. We supply standard metric and imperial sizes from stock and source or manufacture non standard, oversize and obsolete profiles, including seals reverse engineered from a sample or a drawing.