Proper Seal Provides Protection Against Contamination
Contamination is one of most common causes of bearing failures but it is easily preventable. More facilities than ever are implementing lubrication “best practices” such as organizing a clean room for lubricant storage, using a filter cart to filter bulk oils and installing Des-Case desiccant breathers on bulk storage containers and on gearboxes. These are highly effective and efficient measures to keep oil contaminant-free in bulk storage containers and within gearboxes.
The next step to ensuring clean oil within your equipment is to take a good, close look at your oil seals. An oil seal’s primary function is to keep oil contained within the equipment, and its secondary function is to keep contaminants out of the oil. While they typically do a good job of keeping oil contained, dirt and moisture usually make their way around the lip of the seal and contaminate the lubricant, which could result in premature failure of your equipment. There are several reasons that a lip seal could be allowing contaminants into your equipment.
Are you using a double lip seal? This may seem like a good idea but in many instances a double lip seal can actually allow more contaminants into your oil than a single lip seal. In high speed applications, the outer lip will wear faster than the inner lip causing dust, dirt and moisture to accumulate between the two lips. When the inner lip eventually fails, the contaminants will make their way into the clean oil.
Is the seal being damaged during installation? If the seal has to pass over grooves on the shaft during installation, it is important to cover those grooves with heavy tape to prevent damage to the seal’s lip. Whenever possible, install an oil seal with a seal installation tool. This will ensure the seal goes into the bore evenly and without damaging the seal. If you must use a mallet, place a piece of soft wood on top of the seal and strike the wood with the mallet instead of striking the seal. The blows must be soft or the inner spring of the oil seal could dislodge without you knowing, and cause contaminants to enter under the lip.
A radial lip seal can only function well on a shaft surface that is in good condition. Over time, lip seals wear a groove into the shaft on which it seals. This eventually creates a gap between the lip and the shaft and allows dirt and water to contaminate the oil inside the equipment. If you detect a groove on the shaft where the lip of the seal contacts it, you should install a wear sleeve so the lip seal will have a proper surface to seal against. Smaller wear sleeves can usually slip right over the shaft and require no machining, and in most cases you don’t need to change the size of the lip seal you are using.
If your equipment is in a highly contaminated environment, installing a V-ring in addition to an oil seal will be an effective way of keeping dirt and water from contaminating the oil in your equipment.
V-rings are axial shaft seals and, unlike a radial lip seal which is installed into the bore while the lip contacts the shaft, the V-ring is stretch-fitted around the shaft while the lip seals against a counter face on the equipment.
The combination of a radial lip oil seal, wear sleeve and a V-ring is the most highly effective and inexpensive sealing method of keeping contaminants out of the oil in your equipment.
Because every application is different, you should discuss these sealing methods with your oil seal supplier and your Bel-Ray representative.