The reliability of most rotating equipment is almost inevitably linked directly to bearing life, and one of the primary factors that influence bearing life is the quality of the lubricant. A major study into equipment reliability has shown that 52% of bearing failures are caused by contamination of the bearing oil, and this 52% is responsible for 20.8% of all rotating equipment failures.
One of the significant contributors to bearing oil contamination is the breathing process required by rotating equipment. When equipment rotates the bearing housing heats up and the oil/air mixture inside expands and is forced through the seal. The problem arises when the equipment cools, which means the oil/air mixture will also cool and contract sucking air and moisture from the external atmosphere through the bearing seal back into the housing. All bearing seals, to work effectively and ensure an extended life, must accommodate this breathing, yet many fail to do so effectively.
The most common method of sealing the bearing housing is via a lip seal. However, lip seals are unable to effectively seal the bearing housing, they rely on surface contact, which results in costly damage to the shafts, and they can’t be used in API applications. An alternative to lips seals is a bearing protector seal. Although some of these address the issues of lip seals, many of these designs are now viewed as out dated and ineffective.
LabTecta®66 – advanced bearing protection
LabTecta®66 is an advanced labyrinth bearing protection seal that incorporates patented dynamic lift technology to protect against the ‘breathing’ issues that contribute to 52% of all bearing failures. This dynamic lift technology uses the centrifugal force of rotating equipment to open a temporary micro gap allowing expansion of the oil air mixture in the bearing housing, which allows the equipment to breathe (Figure 1). When the equipment stops rotating the micro gap immediately closes forming a perfect seal (Figure 2). This prevents dust and moisture being sucked back into the bearing housing and eliminates bearing oil contamination.
Rated to IP66 of the ingress protection code, LabTecta®66 is capable of reducing bearing oil contamination from as high as 83% to just 0.0003%, even when exposed to high pressure water jets. The range is ATEX certified for use in explosive environments and a number of special designs make it suitable for a wide and varied range of applications.
LabTecta®66 is also designed with a thinner cross section and seal length than competing devices, which means that it can be retrofitted on more equipment without having to carry out expensive modifications. Furthermore the design of the LabTecta®66 enables it to be positioned differently on the shaft meaning there is no need to replace shafts already damaged.
Over 10 years of bearing protection
A recent research paper analysed the 120,000-plus LabTecta®66 products that have been supplied in the 8 years since the product was launched. During this 8 year period from January 2006 to September 2013 only fifty two LabTecta®66 bearing protector seals have had to be removed from service. After detailed examination, it was concluded that any abnormality was found to be operator based including mis-installation and lubricant overfilling, proving that in the 8 years since launch, no LabTecta®66 has ever failed due to the design of the product.
The research also conducted an accelerated life test with a stop start cycle of 4 times a day, which determined that the average LabTecta®66 life expectancy was over 10.5 years. The paper also shows that by using an established statistical (WeiBayes) technique, the average life expectancy was also in excess of 10.5 years. However, because such statistical data can only be modelled with failure data, and as no LabTecta®66 has ever failed, the results have to be viewed as conservative.
With an average life expectancy of over 10.5 years a LabTecta®66 bearing protector seal has been proven to be the most effective way of protecting and extending the life of the bearing fluid and hence the bearing itself. The cost of this kind of protection is a fraction of the cost compared to equipment failures, machine downtime, loss of production and extended maintenance requirements that are caused by bearing failure. The real life examples of LabTecta®66 show that such upgrades can have payback periods as low as 1 month, and even in the moisture laden environment of pulp and paper manufacture, LabTecta®66 has the longevity that both experimental and statistical data suggests.
Case Study 1
A leading paint manufacturer had issues with an OEM lip seal that was failing to prevent leaking paint entering a motor. This was causing the motor to fail every few months at a cost of over £6,000 per annum. The cost of replacing the lip seal with the LabTecta®66 was repaid within 1 month of fitting and is saving the customer over £6,000 per annum in reduced maintenance costs and an expected 9.5 days per year of lost production.
Case Study 2
A paper mill in the USA was having repeated failures with excessive amounts of stock leaking into a Hydropulper gearbox sealed with a lip seal. These failures were costing the mill up to $50,000 per outage, and since installing a LabTecta®66TE (top entry) bearing protector seal there has been no failures for over 8 years.
For more information on LabTecta®66 from AESSEAL®, please visit www.labtecta.com
