Although I've written about oil lube systems in centrifugal blowers before, it is still one of the most common reported problems. My best recommendation for preventing oil leaks is still to purchase grease lubricated machines. But I have found at least a couple of installations where there is no evidence of oil leaking from the centrifugal blower. Totally enclosed, gas tight housings with a closed loop oil system works best.
The oil mist does a good job of keeping the bearing lubricated, but it is tough to contain. The type of oil doesn't seem to make any difference. Hoffman turbine, Gardner Denver synthetic Aeon, and Lamson's old SAE30 motor oil all lubricate the bearings fine, and suffer oil leaks. I've had some success using thicker SAE50 motor oil, and even STP additive, but it is certainly not the recommended fix. The most common fix is to drain and refill the oil.
Whenever I receive a call regarding an oil leak, the first thing I recommend is changing the oil. Drain the old oil, clean & dry all exterior surfaces, be sure oil level settings are properly set, and refill with the manufacturer's recommended oil. Most of the time, problem is solved. If not, you have to look deeper.
Recently I had a complaint of an oil leak at the outlet end of a blower, but they also noted the oil in the globe was always copper colored rather than the clear turbine oil that they poured in. In this case, the shaft seal had failed and was allowing the outlet blower air to pressurize the bearing housing, and thereby the oil supply. At another jobsite, I found the oil was foaming inside the bearing housing. This usually means water, or some other contaminant, is present in the oil. The new, SAE30 motor oil, did the same thing, even though it was labelled as non-detergent oil. We changed to another oil brand, and the foaming, and oil leak, was stopped. Bad labeling, or bad oil?
There is also a concern with the oil globe being mounted on the left, or the right, side of the housing. Technically, it is not supposed to make any difference. In the field, sometimes it does. The oil slinger could "draw down" the oil level during operation allowing more oil than needed to enter the housing. When the machine shuts off, the excessive oil leaks out the rear of the bearing housing onto the floor. I believe this is caused by improperly machined, and/or assembled parts, so it is not a common problem.
But I've seen this, and other unusual problems, after the local repair shop repaired the blower. Not all blower repair shops have, or use, qualified personnel and parts. Be sure to select a qualified repair shop. It will save you money!
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