Q & A

"Is the filter blockage indicator the optimum change point for the element?"

No, this is not necessarily the best indication, although it is better than ignoring the indicator. For example, keep in mind that a rupture in the filter media will not be indicated by an increase in pressure drop. If a cleanliness target is set, and this is regularly monitored by a particle counting program, then change the filter when the cleanliness target is exceeded. However, ensure that this is actually the cause of the problem by taking upstream and downstream counts, as well as ensuring the target has not been exceeded because of other ingression sources such as a failed breather.

Also consider monitoring the differential pressure rather than just watching the indicator as experience gained with particle counting will show what pressure is the optimum change point.

Today's Tip

• Long idling in wintertime causes water condensation in the crankcase, this leads to loss of BN (Base Number) and corrosive attack on surfaces, oxidation of oil, etc.

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Book Bits

From the book "The Practical Handbook of Machinery Lubrication":

Circulation oiling systems vary widely as to detail, the particulars of each design depending on the make, size, type and purpose of the turbine.

Oil is taken from a reservoir and delivered at full pump pressure to a header that supplies oil to the governing and control mechanisms. The oil pressure ranges from about 50 psi in some systems to 450 psi in others (3.5 to 31.6 kg/sq cm). Oil from the bearings and governor mechanism drains back to the reservoir.

A reservoir capacity of five to ten times the volume of oil circulated per minute is recommended. Sizes therefore range from a few, to several thousand gallons. Large reservoirs are fabricated from steel plate and are provided with manholes to permit entrance for cleaning.

Reservoirs should have a bottom that slopes slightly (1 unit in 24) toward a drain connection through which contaminants may be removed. To prevent foaming, oil return lines are generally arranged so that they enter the tank horizontally just above, or at the oil level and at a point above the lowest part of the sloping tank bottom.

For more information about the book "The Practical Handbook of Machinery Lubrication" go to:

http://www.noria.com/secure/product_detail.asp?catalogid=55

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