Rich,

I'm looking through the McMaster-Carr catalog and am finding a bewildering
number of filter cartridges. None of them mention the term "depth
media" or such. Many come in regular and pleated versions. I did
find a nice SS housing with a T handle. It seems that a string-wound
polyester with 304 SS core is OK. I also see a Spun Polypropylene
media for $2.69 ea but the pleated version costs a whopping $30.

Doug
s/v Callista

"Rich Hampel" wrote in message
...
Please appreciate that I dont want to appear to be an arrogant
know-it-all after being in on and aroud critical filtration/separation
most of mworking life ... and yet give just enough information that
each can take and arrive a result that is based on current or
state-of-the-art results.

ANY filter media (including compressed pubic hair) thats used in a
recirculation polishing system will work ... its all a matter of
degree. Whats wrong with TP, etc. is that the material used to filter
is not bonded, can digest (make more particles) in the presence of
water --- thus to do the exact opposite of what you are trying to do.
If doesnt matter if rust, bacteria or broken up toilet paper fibers
blocks the final filter to your engine... expecially during an
emergency. Unbonded cellulose is notorious for unloading particles or
allowing the particles to migrate through the filter .... OK if the
main system is not drawing fuel thats OK as the recirculating slurry
will probably be recaptured; but, if all hell breaks loose and you have
a high fuel demand at the time when the TP decides to unload itself or
its already trapped debris .... the whole system can catastrophically
fail ....

My objection to TP - very poor efficiency, migrates particles, migrates
fibers, unloads at increasing differential pressure, larger first cost
due to need for larger diameter housing, no constancy of retention,
knife edge seals of 'cartridge' - very limited in retention and VERY
prone to bypass. Short life due to low surface area. TP will '
deform' - wrinkle into a smaller mass when heavily laden and
differential pressure is high (remember those knife edge seals) then
unload and bypass.

As far as experience ..... the high tech/high purity industry used such
devices for many years: loose fiberglass, Kotex pads, string wound
cylinders, TP, chopped cellulose ....... until after WWII the world
started using captured German technology: membranes, cartridges, etc.
If TP were any good, industry would still be using it. The last such
system I personally replaced/upgraded was in the mid 70s. ..... as a
cost cutting measure!!!!!

DO NOT depend on filters to remove the crud in your system. If they
plug it means that you are contaminated and need to clean your fuel
system. Such plugging clearly indicates a **symptom**, the filters
prevented the symptom from becoming an extremis situation. If your
system is plugging filters, they did do their job as they are supposed
to .... but now go back in and clean the system! Resident particles
form and agglomerate into more particles. Bacterial scums feed other
bacteria, etc. Your symptoms of plugging filters means your system is
contaminated.... a filtration system is a band-aid or a 'condom' to
prevent stoppage. Consider to thoroughly mechanically CLEAN the tank.


;-)

In article , Steven Shelikoff
wrote:

Rich,

I appreciate that you seem to be an expert on filtering theory even
though you also seem to lack the practical experience of actually using
the TP or PT depth filters we're talking about. I realize you don't
think they work. Even so, I'd love to hear your expert opinion
(absolutely no sarcasm intened) on why my Racor 2uM filter has lasted so
long (2 years now and still not clogged) after installing a TP prefilter
when I completely clogged two of the same filters in 20 minutes each
before installing the TP prefilter.

Steve