VIT OIL MIST- Technical Discussion

ANSI Pump Bearing Temperature Problem

Tests show that ANSI pump bearings (and the oil lubricates that cools them) that use the "flood oil bath" lubrication method can run as high as 180-220f, and very commonly run in the 160-180f range. The actual temperature depends on factors such as pump rpm, load, oil level, oil viscosity, ambient temperature, etc. Tests that were conducted with various brands that use flood oil bath showed this to be true.

What's wrong with "flood oil lubrication"?

Flooded bearings generate heat, which is a killer for bearings. It's simple to understand why. The oil level is set according to the pump manufacturers instructions, so the bottom end of ball bearings are half submerged. Try running back and forth in a swimming pool with the water at waist level.There is a tremendous amount of "viscous drag" or "friction". Now try running back and forth in water at the speed of a ball bearing!!! Image what the ball bearings feel like plowing through viscous oil at that speed and how much frictional heat is being generated. It is quite common for process pumps (especially at 3600 rpm) to be running at 160-180°F

Most of the heat that you feel on a pump frame is frictional heat, not related heat!

What effect does heat have on bearing life?

Bearing life is reduced 2000 hrs B₁₀ for every 10°F (per Goulds Pumps study and presentation at Turbo machinery Symposium). To put that in perspective;     ANSI B73.1 pump specifications allow a bearing life rating of 17,500 hrs B₁₀. Not very much to begin with! (API requires 40,000 hrs +). Now add a 30 or 40 or 50-degree temperature effect and bearing life gets real bad.

What effect does heat have on oil life?

Oil life (oxidation rate & coking like you see when you change the black, gunky oil in your car) is drastically cut with increased temperature. Goulds instruction manual for 3196 - X Series (their newest design) says that ANSI pump bearings commonly run up to 180°F, and that the oil must be changed every 3 months or 2,000 hrs of run time (whichever comes first). Goulds also says to change the oil more often if the enviroment is bad (paraphrased). What plant do you know that changes oil in any ANSI pump every three months?

What other factors on standard ANSI pumps detract from bearing life?

(1) ANSI Pump bearing frames do not hold much oil.  There is not much reserve capacity, and there is not much of a heat sink to absorb and dissipate the heat that is generated. (2) Design for heat dissipation is very poor. No ribs. No fins. No fans. (3) Constant level oilers are a major problem. This was demonstrated by Goulds in the same study, and called the "burping problem".  (4) Vents and breathers allow moisture to infiltrate the bearing frame, adding, "water content" to the oil (dry oil readily absorbs moisture). Moisture (water content) in oil will drastically reduce bearing life.

Only 0.006% moisture content (barely a drop of water in the frame) will cut bearing life in half!!!

The solution- Oil Mist Lubrication

What is the absolute best-proven way to lubricate antifriction (ball & roller) bearings?

It's indisputable- it's oil mist.

The problem is that the traditional oil mist systems have been big, bulky and expensive, so they are used primarily in the oil refining industry for critical machinery (big pumps, turbines, compressors, etc.) lubrication. It is so well proven that you can find whole textbooks written on this subject. There are companies that do nothing but build oil mist systems. The issue is...everything else (flood oil, grease, etc.) is a compromise.

What are you giving up? Run Life - Run Life - Run Life.

Simplicity

To avoid the complicated, expensive systems commonly used in the oil refining industry, Environamics developed an internal self-contained oil mist generator technology in 1993. This is the standard feature on all Environamics/EnviroPump and Seal, Inc.,  VIT-Pumps and VIT Power End Upgrades. It is now in operation in thousands of pumps in almost every industry.

The Bottom Line

Reduce bearing operating temperatures by as much as 50-60F with the "non flooded" bearing arrangement, using the VIT self-contained oil mist technology.

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