Radial seals: how to measure shaft, housing and height, and which design to choose

A radial seal is a seal mounted in a fixed housing that rubs against a rotating shaft to prevent lubricant loss and contaminant ingress. It is used in gearboxes, motors, pumps, bearings and any equipment with a shaft passing through a casing.

The typical design includes an elastomeric body, a lip spring and, in many cases, an outer metal case. The lip is the part that contacts the shaft, and its correct installation is key for the seal to perform its function.

In Argentine industry, radial seals are available in standard and special sizes. Brands such as DBH, SKF and FAG offer a wide variety of profiles and materials, and at MR Accesorios Industriales we stock these lines so you can find the right replacement.

To order a radial seal you need three measurements: shaft diameter, housing diameter and height (width). They are expressed in millimeters and generally in that order: shaft x housing x height. For example, a 30x47x7 seal fits a 30 mm shaft, a 47 mm housing and is 7 mm wide.

Measure the shaft with a caliper in the area where the lip rests, not on a worn part. The housing is measured at the inner diameter of the cavity where the seal fits. The height is the total thickness, including the metal case if present.

If the old seal is badly damaged, you can measure the housing and shaft directly. If in doubt, consult the equipment manual or send us a photo with measurements via WhatsApp; we'll help you identify the model.

The most common design is the spring-loaded seal (SC type), which maintains lip pressure on the shaft. There are variants without a spring for low-speed or heavily lubricated applications, and designs with a double lip that include a secondary lip to retain contaminants.

There are also seals with an outer lip (TC type) that are mounted in open housings, and seals with a full or partial metal case. The choice depends on working conditions: speed, temperature, pressure and type of lubricant.

At MR Accesorios Industriales we work with seals from different brands and profiles. If you don't know which design to choose, we quote based on measurements and application, indicating the most suitable alternative.

The lip material determines resistance to temperature and chemicals. Nitrile (NBR) is the most used: it withstands up to 100 °C and is compatible with mineral oils. Viton (FKM) resists up to 200 °C and aggressive fluids, but is more expensive.

There are also silicone, polyurethane and PTFE seals for special applications. When choosing, consider the working temperature, the type of oil or grease and the presence of water or contaminants.

If you have doubts about the material, send us the working conditions and we'll advise you. We stock seals in different materials from brands DBH, SKF and FAG, and we can indicate the correct option.

A frequent mistake is installing the seal backwards: the lip must point towards the fluid to be retained. If mounted inverted, it leaks oil immediately. Another problem is damaging the lip when passing it over keyways or threads without protecting the shaft.

It is also common to use a seal with the wrong size, causing leaks or premature wear. Always verify the three measurements and the profile type before buying.

To avoid failures, clean the housing well, lubricate the lip with the working fluid and use proper tools for assembly. If you need help, consult us: we'll indicate the correct seal and give you installation recommendations.

To give you an idea, some radial seal codes we stock are 1289 and 5069 from DBH, 8796 and 1850 from SKF, and 32332 from FAG. These codes correspond to specific sizes and designs; if you have one of them, you can order it directly.

If you don't have the code, measurements are enough: tell us shaft, housing and height, and we'll quote the equivalent seal in your preferred brand. You can also send us a photo of the old seal with a ruler next to it.

Remember that codes may vary by manufacturer. Therefore, it is always better to confirm measurements. At MR Accesorios Industriales we help you identify the correct replacement.

At MR Accesorios Industriales, from Buenos Aires, Argentina, we stock radial seals from recognized brands such as DBH, SKF and FAG. We work with a wide variety of sizes and designs to meet industry needs.

You can request a quote for your radial seal via WhatsApp or email. Send us the code, measurements (shaft x housing x height) or a photo of the part, and we'll respond promptly with the proposal.

Don't hesitate to contact us if you have doubts about which seal to choose. Our team advises you to find the right replacement and avoid unnecessary downtime.