The Beer and Peanut Test

Aeration can be a major cause for concern in lubricating systems causing oil film strength failure, cavitation, premature oxidation and compressibility problems.

Possible causes of excessive air entrainment include water and particulate contamination, suction line leaks, plunging return lines and poor system design.

If the problem can be traced to system design, there are a number of ways to solve the problem including using diffusers on the return line, installing baffles in the reservoir to reduce turbulence and to prevent oil with entrained air from the return line directly entering the suction line, and installing a 60 mesh screen to act as a nucleation site for bubbles to coalesce.

To test the theory of nucleation to aid bubble formation, try the following:
Take a freshly poured glass of beer and drop a salted peanut into the glass. Watch as the weight of the peanut causes it to sink to the bottom of the glass.

But keep watching! After 10 to 20 seconds, the peanut miraculously rises to the surface again. The reason is that the salt grains on the surface of the peanut act as nucleation sites for the growth of gas bubbles, in this case, carbon dioxide from the carbonization process.

When the peanut reaches the surface, the gas bubbles detach from the surface of the peanut and once again, the peanut will sink to the bottom, where the process starts again. Depending on how much salt is on the surface, this pendulous activity can continue for several minutes, until finally all the salt is washed away and the peanut falls to its final resting place . . . with only one way to remove it!

Now that’s one science experiment worth trying . . . Cheers!

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