Sundyne LMV-801 intermediate bearing box failures

[ME1289]

Does anyone have experience with a vertical Sundyne LMV-801 with an intermediate bearing box between the motor and the pump?

We have a pair of 15 HP pumps that have experienced repeat bearing failures even after factory troubleshooting. Pumps are high suction pressure (~400 PSIG) and typically run around 60 GPM with 50 PSI differential. We're pumping cold, light end hydrocarbons. Pumps run at 3530 RPM.

The bearing box has a small oil reservoir and lube oil disk that moves oil up internal galleys and trickles down the bearings and shaft.
The bearings run very hot in the summer with skin temperatures approaching 190F on 90F ambient days. This seems too high to me. We run a high quality Royal Purple 46 weight synthetic. We got about 6 months out of the last set of bearings

The high temperature leads me to believe we are overloading the bearings with thrust but I'm also skeptical about the lubrication setup. Not sure how to measure our oil flow to ensure the bearings are getting adequately lubricated.

Additionally, the bearing box doesn't have any cooling fins (like a standard bearing power end on a horizontal pump) or forced cooling so I question it's ability to reject heat. Also, since the motor is physically small, the 'windage' from the motor fan doesn't really circulate around the bearings either.

Could be a combination of all three factors (thrust, poor lubrication, poor heat rejection) or just one.

Anyone have experience with this bearing setup? I'm only familiar with close coupled Sundyne pumps where the impeller is connected directly to an extended shaft motor with no intermediate bearings.

Thanks!

 

[electricpete]

I don't have experience with that type of machine. The closest I can compare it to is an ansi pump.

We run a high quality Royal Purple 46 weight synthetic. We got about 6 months out of the last set of bearings

If viscosity grade can be reduced to ISO32, that might cool things down compared to ISO46.

Also if high quality means high viscosity index, that will limit reduction of viscosity with increasing temperature which might be viewed as a good thing when the heat is coming from something other than the bearing (is it?), but if the heat is coming primarily from the bearing itself then high VI might just mean that everything runs hotter (for a given iso grade)

So if it were me I'd ask the OEM if I could change the oil type to ISO32 and maybe lower VI. For that matter if you have the luxury of talking to the OEM of course you should get his take on the broader questions.

I'm also skeptical about the lubrication setup. Not sure how to measure our oil flow to ensure the bearings are getting adequately lubricated.

From a distance, it sounds like an ok oil delivery method to me (usually not much oil is needed and too much oil just makes it run hotter). Since you have a mechanism to lift oil up onto the bearings, I'd assume the oil level should be below the bearings (oil level too high can cause hot bearings)

In general if temperatures are higher than normal then aside from the factors you mentioned we might look for clues in vib analysis, oil analysis, inspection of removed bearings and maybe alignment (if alignment applies to your machine, I'm not clear). That's pretty generic, I apologize. Take it fwiw from someone who hasn't seen any machines like this.

 

[Artisi]

impossible to diagnose from a short internet posting. A few photo's of a failed bearing would certainly help - but you best solution is to get the bearing manufacturer involved by analysing the failure, this will give you a starting point for a better understanding of where to start and what to look for, ie., lubrication failure, thrust, ball sliding and not rolling, overheating etc.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)