As you know the constant level oiler is a not difficult, safe and operative way to maintain accurate oil level in equipment. Constant level oiler has a control principle that must bring in to line with the proper oil level of the equipment.
The oiler is installed outside on the equipment sump and oil is filled up to the proper level. If the sump oil level decrease, the air enter to the glass container displacing the oil until the oil level get back to proper level. In our refinery are installed thousands of this type of oilers. Although the maintenance are very familiar with oiler operation we experienced a catastrophic failure of a centrifugal pump bearing due the improper lubrication in spite of normal oil level of an oiler reservoir. The bearing casing has been removed and found a less quantity of oil than normal.
First we supposed that nipple (connection fitting between reservoir and pump sump) is obstructed. False supposition. The oiler was removed from the bearing casing and inspected carefully. All the elements of the oiler seems to be OK. Very unusual situation. Nothing was found incorrect but the bearing failure happened for improper lubrication. Must be detected a cause... Finally the oiler was installed again on pump sump and has been checked the horizontality of connection fitting between oiler reservoir and sump wall. What was found? The fitting was mounted with a slighter slope practically invisible by human eye, and the result the oiler was located a little bite lower then the sump. In this way the oiler viewed oil level, but this level was within the fitting, before to end fitting, not inside in pump sump. The causes for this incorrect oiler installation could be:
- the bearing casing could be mounted very less turned due some inadequate pins;
- or while the new bearing casing installation the bore for fitting fixing was not drilled exactly horizontal.
A simple drawing illustrated the encountered error in oiler installation.
incorrect oil level viewed by oiler.
Reader tip provided by
Mares Aurel, Reliability Project, S.C. Petrotel-Lukoil S. A.
Thanks for the tip Mares!
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