Page 428 - Subyek Teknik Mesin - Forsthoffers Best Practice Handbook for Rotating Machinery by William E Forsthoffer

Lube, Seal and Control Oil System Best Practices Best Practice 7 .15

Fig 7.15.6 Shell and tube exchanger data sheet

this case, operation should be transferred to the stand-by greater detail. A typical hydrodynamic oil film bearing will have
cooler and the affected cooler checked for internal a continuous oil film on the order of 0.001 inch (20 to 25
condition. microns) between the shaft and bearing surface at the load
- Systems incorporating air (fin fan) coolers should be sized point. In order to ensure continuous trouble free operation of
conservatively, such that full cooling capacity is available in the bearing, the filters in the system must continuously prevent
high ambient temperature conditions utilizing a realistic the entrance of any particle equal to or greater than 20 to 25
fouling factor. Experience has shown that air coolers are microns clearance into the oil film between the shaft and the
often undersized. In addition, air coolers should be bearing. A typical filtration specification for auxiliary systems is
furnished with dual channels, such that two separate ten microns absolute particle size e that is, the greatest size of
cooler banks, as in the case of shell and tube coolers, are any solid particle in the oil film should be ten microns. This is
present. provided of course, that the filter design does not allow the
bypass of any particles. In general, filtration specifications of 10
to 25 microns are typical of the maximum particle sizes per-
Filters mitted through the filters. It is important to remember that the
The function of filters is to continuously provide clean auxiliary filter sub-system consists of the transfer valves, filters, differ-
fluid to the critical equipment. Let’s investigate that definition in ential pressure indication and alarm across the filter element.

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