Q & A

"How should I calculate my oil consumption ratio and what target should I aim to achieve?"

The consumption ratio is the ratio of how much oil is added to the system in a period (normally a year) to the actual volume of fluid the system holds.

Consumption ratio = Total Oil Added/Total System Volume.

Aim to achieve a target reduction program of 50 percent per year and seek a goal of less than 0.1.

Consider also the disposal ratio which is the ratio of the volume of oil drained from the system in a period to the actual volume of the system. The difference between the two ratios will indicate the leakage ratio (or in the case of crankcase engines, the burn ratio) which should be minimized as much as possible, for both environmental and financial reasons.

Today's Tip

• With the proliferation of digital cameras, why not take a photograph of the oil sample (requires the use of a transparent sample bottle) and store the image in a trending software for comparative purpose. Record a new oil sample and use this as a baseline. Set the bottle against a white background such as a sheet of paper to maintain a consistent color comparison. Use the camera in other ways such as to record images of the machine and sampling point as a means of identifying it in the software, or to record abnormalities such as excessive leakages for easy located by mechanics.

  Pictures are immediate and speak volumes, so use them to good effect in reports and trending software.

Each tip published will earn the sender $10. Send your tips to webmaster@noria.com or fax to 918-746-0925.

Book Bits

From the book "Proactive Maintenance for Mechanical Systems":

Dissolved Air in Fluids

Air absorbed by a liquid is dissolved air. It does not obey Boyles' Law like free or entrained air. However, it does obey Henry's Law - the weight of gas that can dissolve in a liquid is proportional to the gas's absolute pressure. Engineers can remove dissolved air by either subjecting the fluid to a reduced pressure and/or raising the fluid temperature. Thus the solubility of gases in liquids is inversely proportional to the temperature and directly proportional to the pressure.

The presence or absence of dissolved air does not affect the fluid volume. The amount of gas that a particular liquid can dissolve depends upon the gas and liquid composition and the state conditions of temperature and pressure. High solubility is undesirable because the air (or other gas) dissolved at reservoir conditions may come out of solution at a lower pressure (pump inlet, for example) and cause gaseous cavitation. In a pressurized reservoir, the problem worsens because the more air dissolved in the fluid, the more air that can come out of solution later.

For more information about the book "Proactive Maintenance for Mechanical Systems" go to:

http://www.noria.com/secure/product_detail.asp?catalogid=48

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