In the News

Article Courtesy of Pumps & Systems 
By: Rob Dotson, Chief Product Strategist at Inpro/Seal, a Dover Precision Components (DPC) company. 

The bearing isolator’s impact on the pump and motor industry.

For the pumps and motors used in industrial rotating equipment, there is one incontrovertible truth: Bearing failure equals equipment failure. 

Considering that the difference between efficient, reliable operation and a catastrophic breakdown can come down to a single part, bearings are among the most important components in a given operation. Without an effective bearing seal to retain lubrication and prevent moisture and contaminants from entering the bearings and degrading the lubricant, even the most robust rotating equipment can prematurely reach a costly failure point.

While bearings enable the essential operation of heavy-duty pumps and motors, it is the seals that deliver the critical protection needed for long service life. Like many other industrial components, sealing technology has significantly improved with each iteration of the part. In the last 50 years, bearing seals have evolved from a key maintenance accessory to a critical reliability component for operations.

The Evolution of Bearing Seals

The earliest bearing seals were lip seals typically crafted from leather. While these components were adequate at the time, they contacted the shaft, causing wear, and required constant lubrication to function. By the early 1940s, technology evolved to allow manufacturers to develop more effective bearing seals. Rubber compounds allowed manufacturers to create tighter, more resilient lip seals, enabling longer-lasting performance in rotating equipment. 

Contact seals could handle positive pressures and static lubricant levels, but as their name indicates, they operated in direct contact with the shaft, which led to increased wear and a shorter service life. Lubricant leakage and contamination became common problems across various applications, resulting in bearing seizures and equipment breakdowns. By the early 1970s, the industry-wide need for a better bearing seal solution became apparent.

The Arrival of the Bearing Isolator

In February 1975, David Orlowski, a pump repair shop owner, was called to retrofit more than a dozen American Petroleum Institute (API) refinery pumps on-site at the Sears (now Willis) Tower in Chicago. Even during the frigid winter, an entire side of the famous building needed to be cooled due to the daytime solar load. Refinery pumps were used in the heating, ventilation and air conditioning (HVAC) system and were equipped with rubber lip seals, a rare combination that was not optimal for the application. The pumps first leaked through the mechanical seals, then past the worn lip seals, allowing water to enter the bearing housing and triggering catastrophic failures that ultimately shut down the cooling system. Once the cooling system failed, the building experienced thermal expansion due to the heat, causing windows to fall to the streets below.

Orlowski retrofitted the pumps with a common rotor and stator seal design that had been used for 30 years on pumps in refineries and petrochemical plants, solving the issue. Encouraged by this success, he became driven to bring a similar technology to process pumps, where rubber lip seals were still standard. He installed this common design on a series of process pumps with mixed results, revealing the need for more research and development.

After approximately six months of extensive development and testing, Orlowski and his team perfected a compound labyrinth rotor and stator combination tailored for process pumps. It sealed oil within the bearing housing and prevented contaminants from entering, even under extreme pressure equivalent to a firehose spray. He named this component the bearing isolator. 

In simple terms, bearing isolators are compound labyrinth seals that use rotor and stator geometry with carefully engineered clearances to create a dynamic labyrinth path. The stator captures oil splash and directs it back to the bearing housing, while the rotor uses centrifugal force and gravity to expel contaminants away from the seal interface before they can reach the bearing cavity. Because the bearing isolator operates without contact, it has no wearing parts. In addition, the rotor and drive ring rotate with the shaft, preventing shaft wear and grooving.

The first bearing isolators were installed in the summer of 1975 at a plant in Muscatine, Iowa, which was the world’s largest producer of potable ethanol. These seals were used on critical equipment that required an intense spray down each night to remove carbohydrates and mash that would accumulate on the pumps. 

A Turning Point

The advent of the bearing isolator provided OEMs and end users with a noncontact seal that improved performance life, extended run times, increased maintenance cycles and lowered production costs. But industry-wide adoption did not happen right away. Initially, OEMs hesitated due to a lack of clear cost benefits, as a large part (in some cases up to 80%) of their profits at the time came from replacement parts. Many end users, however, quickly embraced the new system. They saw that the bearing isolator was ideal for making pumps last longer, run more efficiently and deliver better total cost of ownership (TCO).

In 1978, the industry reached a turning point when a major pump OEM offered the bearing isolator as an upgraded sealing component. Soon, end users began to request bearing isolators on their newly purchased pumps and OEMs came to realize the benefits the bearing isolator delivered for preventative maintenance programs. More widespread adoption began to take hold, but testing and engineering did not stop there. 

In 1994, another significant event occurred when bearing-protection requirements were written into the Institute of Electrical and Electronics Engineers (IEEE) Standard 841 motor specifications, bringing noncontact labyrinth seals into the mainstream. Manufacturers began to extend warranties from one year to two and eventually to five, thanks to improved risk management, easier preventative maintenance and longer maintenance cycles. Over the years, new applications, operational processes and expanded requirements across industries demanded continual improvements for bearing sealing. To that end, a slew of new bearing isolator products continued to enter the market throughout the 2000s, including IP66 rated designs, innovative features and smaller geometries to fit a variety of equipment sizes. 

But if the last 50 years are any indication, the next advancements in bearing isolators will continue the pathfinding nature that the industry has come to expect.

Looking to the Future of Bearing Seal Technology

From the earliest days of leather seals to today’s more advanced features and designs, this critical component continues to evolve. It is safe to say that in 1975, few could foresee just how much the bearing isolator would change the landscape of the industrial pump and motor industry. At the time, it was certainly a creative innovation. But decades later, after extensive application experience, field testing and an exhaustive development process, the question becomes, “What’s next?”

One avenue likely to be explored is moving beyond standard or passive sealing to drive innovation toward more active systems. Given the improvement in preventative maintenance the bearing isolator has delivered from day one, modern design innovations can further develop bearing protection into a critical component of next-generation reliability systems. Ever an evolving part, the bearing isolator continues to undergo design and development enhancements that improve performance, extend warranty and maintenance cycles and reduce TCO for operators.  

This article originally appeared on Pumps & Systems.