INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Jobs

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

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

(OP)
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

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

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.

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

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.

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

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

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

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.  

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

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

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

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

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

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,...)

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

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

 

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close