This helps alot, thanks! LaBomba suggested that just amking
the primary filter bigger would solve the problem. I was thinking
that this might be a easier solution, but it appears that a separate
polishing system does have advantages over just using a filter
that does not clog up so quickly. My intended strategy is to oly
fill one tank at a time, set the newly filled tank to polishing while
running the engine off of the other tank. Then when the engine
tank gets low, switch the engine to the polished tank, then
fill and polish the other tank. That way I always have clean
fuel ready and waiting (and plenty of it) and I don;t have to rush
to fill again.
I'm still in a quandry about Raycor style filters vs the paper towel
roll type. Perhaps RichH will chime in on this one since he is an
expert on filtration systems. Does Safeway carry 15 uM paper towels?
Doug
s/v Callista
"Roy G. Biv" wrote in message
om...
"Doug Dotson" wrote in message
...
Makes sense, but there is quite alot of evidence out there that
a polishing system is a good thing to have. I can't really
increase the size of my on-engine filter. I could increase the
size of the Raycor, but at the pore sizes I run (30 micron) in it make
it
necessary to change the on-engine filter regularly as well.
Bigger Raycor won't fix the problem.
Doug
"LaBomba182" wrote in message
Just go up a size or two in your filters. The surface area difference
between a
500 Racor and a 900 Racor is tremendous.
Actually the larger surface area of the element of the 900 or 1000
might help;
My theory was independent polisher with small pore size (Racor) but
RichH (who has not contributed to this thread) on polishing explained
it this way:
Complete Thread (26 articles)
Original Format
Newsgroups: rec.boats.cruising
Date: 2003-09-17 07:33:31 PST
RichH wrote:
If your polishing system is 'off line' ... not a part of the normal
fuel
distribution and return loop the following will exponentially improve
the retention ability and 'speed of recovery' if you happen to get a
load a cruddy fuel or the sea state breaks a slug of particale loose
from the tank walls, etc.:
Dont use 2uM filters in the loop! .... increase the nominal retention
rating to 10 or 15uM and the resultant final particle distribution *in
the tank* will be essentially zero and accomplish this level FASTER.
...
here's why:
Fibrous media filters have retention capability at essentially ALL
particle size levels. A 15uM fuel filter will remove approx 85 to 95%
of
of 15uM particles in a one single pass of the fluid through it, at
10uM
50%, at 5uM perhaps 30%, at 2uM maybe 15%. A 15uM filter will have
approx 4 to 5 times the flow rate capacity (gallons per minute per
psid)
of a 2uM filter ... meaning that the 15uM filter will cause less work
for the pump and overall flow will be FASTER. A 2uM filter will
deposit
2uM particles primarily on the surface of the media, a larger
retention
media will capture 2uM particles down deep in the media (for *more*
capacity of small particles) Since a polishing system is a closed
recirculation system you are constantly filtering the same fluid over
and over and over, each time the fluid passes through the filter it
leaves a few percent of smaller particles behind in the filter, since
a
larger retention filter has better flow characteristics the pump will
push through MORE fluid per minute and have less amperage draw. When
using a 2uM filter, the fluid returned during recirculation to the
tank
is again mixed with particle/debris laden fluid. A larger retention
filter will do the same job, to the same level of particles in the
tank
.... and do it faster because the larger retention filter has less
resistance to flow. With less resistance to flow a larger retention
filter will have less probability of extruding and releasing
SOFT/DEFORMABLE particles at it approaches differential pressures that
would 'clog' a filter.
Another benefit - If for example you have a crud contamination hanging
on the walls of the tank and the sea state causes the attached
particles/crud to break free and enter the fluid, the larger retention
filter (because of its less resistance to flow) will recover the tank
back to an acceptable particle distribution (particle recovery)
FASTER
than a smaller retention filter. Same story when taking onboard a load
of fuel that is contaminated.
Recirculation filtration is exponentially faster, more efficient, and
vastly more cost effective than single pass filtration. Use the
largest
filter retention possible (~10-20uM) to effect the fastest tank
turn-over... the tank will after a few turn-overs be to the same level
of residence particles. For the mathematicians, what is happening is
an
exponential decay of resident particles *in the tank*; since the
larger
retention filter (even with less efficiency with respect to the
'target
retention') is Faster because the exponential decay 'in the tank' is
faster. If you have time to burn, take ANY filter (includes compressed
pubic hair), recirculate for looooong times and you will have
essentially ZERO particles in the tank. Typically in industry a
recirc.
filter is sized about 5 to 10 times the size of the target residual
retention.
hope this helps. (RichH)
---
Captkeywest wrote:
no bs at all...
my permanently installed independent polishing system draws about 5
gallons (100 gallon tank) every 6.5 minutes through a racor 1000 with
2 micron (can switch to racor 900 when 1000's vacuum increases)
the engine has a racor 500 with 10 micron , then racor 500 with 2
micron, then the perkins 4-108 engine mounted filter.
as rich points out the 1000 elements aren't much more expensive than
the 500 elements, don't let the 500/1000 designations throw you, the
surface area of the 1000 is MUCH greater than twice the surface area
of the 500......
source:
http://groups.google.com/groups?hl=e...4%40NOSPAM.net