![]() Yet for oil mist to reach the bearings, atomized oil droplets admitted at a single point near the center of the bearing housing must turn and travel horizontally. It should also be noted that certain bearing cages create “windage”- a fan effect that tends to push the mist away from the rolling elements. They then tend to fall out of suspension to the bottom. Quite obviously, as oil mist enters through an application orifice into the much larger bearing housing, its velocity will slow down.ĭroplets collide and become larger. Plant-wide oil mist lubrication evolved at about the same time as rotating labyrinth isolators (1960s and ’70s), and the dependence of earlier oil mist application methods on leaking labyrinth technology can be seen in Figure 1. ![]() The MTBF benefits of oil mist over oil traditional sump lubrication of rolling element bearings have been well-documented, and the oil mist lubrication option was included beginning with the API-610 Seventh Edition in 1989. Maintaining an oil fog environment at all times greatly reduces bearing degradation and the resulting risk of premature failure. Protection of nonrunning (standby) pumps. Reduced power requirements, because the bearings operate in a thin film of oil instead of plowing through a pool of oil. Lower operating temperatures, typically 10☏ and often 20☏ (approximately 6☌ to 12☌). It is no longer necessary to rely on operators to check and fill housings with oil.īetter lubricant properties, because the oil on the bearings is always new. The advantages of oil mist lubrication include:Īlmost completely maintenance-free and self-checking. The coalesced oil finally passes through a hole in the bottom of the housing and is collected for disposal (Figure 1). This air/oil mixture passes into the housing, where some of it contacts and lubricates the bearings, while much of it falls straight through to the bottom of the housing. The mist, which has the appearance of light smoke, is moved out to the pumps via two-inch or four-inch piping in a low-pressure (less than 1 psi, approximately 5 to 6 kPa), low-velocity (less than 7 ft/s, about 2 m/s) process.Īt the pump, the oil mist is inserted into each pump bearing housing through a small-diameter application fitting or reclassifier, which greatly increases the mist velocity, causing the droplets to collide and coalesce into larger, liquid drops of oil. The mist is a mixture of atomized (less than three-micron) oil droplets mixed with air in a ratio of about 1:200,000. Instead, an entirely static oil mist generator creates the oil mist in a central module that services all pumps within a radius of approximately 600 to 1,000 feet. The basic process description is as follows: First, no liquid oil is placed in the bearing housing. Oil mist lubrication has been successfully used for pumps and their electric motor drivers in petrochemical plants since the 1960s. MTBFs as high as 10.2 years are now on record at some of the more exceptional refineries. Indeed, oil mist lubrication is recognized as a key part of an API-based maintenance program at many refineries and pump mean time between failures (MTBF) of four to six years are being routinely achieved. West Coast consulting engineer estimated that more than 50 percent of all U.S refineries are using oil mist. In this part of Texas, approximately 80 percent of the pumps at each refinery were serviced by the oil mist system. ![]() Estimates of oil mist usage at 30 refineries in the Beaumont-Port Arthur area ranged from 80 to 90 percent. The targeted surveys by the Houston-based provider confirmed that oil mist lubrication is the predominant method of lubricating pumps throughout the refining industry in the United States. Additionally, the application of cartridge-type API-610 10th (2006) edition-compliant, face-type quasi-hermetic seals in pump and electric motor applications will also be discussed. This article covers an overview of oil mist lubrication, along with a brief review of past and current best practices in pumps and electric motors. With this outdated and environmentally unfriendly type of Note that advanced face-typeīearing protector seals should not be used in conjunction Old-style (non-API type) oil mist insertion at The survey identified important opportunities for cost-effective reliability enhancements.įigure 1. However, although it was assumed that the actual installation details for oil mist technology followed state-of-art practices, this was not always found to be the case. These refineries had adopted using pure oil mist lubrication on thousands of pumps. The refineries’ pump bearing protection practices became the subject of closer scrutiny. Gulf Coast oil refineries relating to their oil consumption, mean-time-between-failure (MTBF) and lube application methods. A few years ago, a well-known lubricant and services provider conducted a survey of eight large U.S.
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