At what size do emergency / service generators require pre-lube pumps

[davster01]

Hi,

I would like to know what is the threshold value at which the service and emergency generators typically have a pre-lube pumps.

By the way, I am typically involved with land-based units under 60 kW. We do not have such pre-lube pumps.

Thank you

 

[JLSeagull]

Typically pre-lube is not a significant issue compared to post-lube due to the DC battery requirements. The requirements varies by manufacturer. Some 5000 kW GE/Nuovo Pignone turbines may require extensive post-lube (eight-hours) where some 25000 kW GE turbines may not. I don't recall this being a big issue with Solar.

 

[rovineye]

The smallest gen sets I have dealt with were about 1600 kW (900 or 1800 RPM), and at that level the generator bearing required pre-lube, but not the engine.

 

[MikeHalloran]

I think the threshold for prelube has to do with the difficulty/expense/logistics of replacing the bearings in the prime mover.

Most of the yacht generators with which I have dealt, Diesels between 40 and 250 kWE, don't have prelube pumps.

All of the oil rig generators with which I have dealt, mostly natural gas engines 40kWE and above, do have prelube pumps, and oil heaters, which are run on a regular basis to keep the crank and oil warm.



Mike Halloran
Pembroke Pines, FL, USA

 

[dicer]

From the smallest to the largest will all benifit from prelube, it for sure will not hurt a thing, especially if there are long time periods that the engine isn't run.

 

[BrianBT]

As before it depends very much on the manufacturer. I have sailed with 500kW Detroits without prelube and 500kW Yanmars with.

I don't think I have seen anything above 500kW without

 

[waross]

Post lube on the turbos is often an issue. Standard practice on the smaller sets is a cool-down period. A normal stop will shed the load and then let the engine run at no load for a number of minutes to allow the turbo time to spool down before stopping the engine.
I have worked on a lot of shore based sets, both standby and prime power. Size range up to about 1.2 megaWatts. I haven't seen a pre-lube system. I see some crank-case heaters and most turbos have a cool-down stopping sequence.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[CH5OH]

prelube pump = bearing lifetime
the "damage" done on each start depends upon time required to pressure the lube manifold (viscosity,lenght suction pipe,wear lube pump,...)

 

[powerjunx]

small emergency generator engine fitted with pre-lube pump is irrelevant, though it incurs friction on bearing surface but insignificant issue. The engine speeds up to rated speed less than 5 seconds, lube pressure builds up..with less than 45 seconds upon start up it supplies power to the system, in compliance of SOLAS requirements.


"..the more, the merrier" Genghis Khan