You obviouslly have a good well designed system.
For improvement I'd depend more on the polisher. That you're only
getting 200 hours on a large flow system to me indicates that you could
probably benefit from better polishing.

You might want to change your recirc. 10µM to a 5µM ... or better yet
use a 5µM 'depth filter' in that location. Youll have to do a cross
reference search (thats what the internet is for) for equivalence for
any depth type filter to be used in a Racor housing. But, be wary of
any filter that doesnt say 'absolute' or some % retention when
describing the retention rating - the single statement such as '5
microns' is a potential warning that such a filter is a 'nominally
rated' filter and may have poor % retention at 5 microns. Whats the
'turnover rate' of your onboard polisher and how often do you need to
change that filter and at what differential pressure? The 'faster'
you turnover a tank with a polishing system the better the particle
removal ... polishers are not dependent primarily on 'retention rating
of the filter' but how MUCH fuel you can turnover. For boat tanks I
usually target to turnover the 'whole' tankage in about ~1.5 - 2 hours
through the polisher.

In article , Wayne.B
wrote:

On Sat, 08 Dec 2007 19:21:04 GMT, Rich Hampel
wrote:

Most tanks need to be
cleaned out on a regular basis - saves a hell of a lot of filter cost
and hassle at the wrong time.

hope this helps.

Thanks, interesting analysis. Let me play some of this back in my
words with a couple of extra details thrown in. My 10 micron Racors
are the largest size commonly available, Filter Element: 2020TMOR.

The engine mounted 2 micron filter is maufacturer specified, and
significantly smaller than the Racors, probably about 25% in size.

The engines are DD 4-71 2 strokes rated at 280 hp each, with normal
fuel burn is in the range of 2 to 5 gph each.

I think I heard you say that this was a reasonable configuration,
i.e., tank 10 2 lift pump engine. I do have an independant
polishing loop which I use when the boat is docked for extended times.
It cycles through a large Racor 10 micron and returns to the tank.

Something must be working reasonably well because I've been averaging
over 200 hours on the 2020TMORs before replacement.