fuel filter fittings

[Robert Harris]

Used to work at a major chemical plant. The plant used literally millions of 
compression fittings - both brass and stainless on dozens of chemicals from 
inert gas to some highly corrosive stuff, at instrument to process (several 
thousand pound )  pressure, installed by everyone from construction crews to 
plant operators and maintenance.  Leakage and breakage were extremely rare - in 
fact if it held up under initial pressure, you never had any problem.  Of 
coarse, the copper tubing and fittings were quality stuff, not the cheap thin 
crap sold in auto parts and Home Desperate stores and the tools used weren't 
imported from china.  Never had a problem, but I have yet to master double 
flaring - but then, I don't do buggy whips well either.

If the first ingredient ain't Habanero, then the rest don't matter.
Other Obsessions: Ferro-Equinary , 1972 "Killer Whale" Mustang
Currently Interred in the Peoples Democratic Republic of California - Stalag 
Montclair
In a country run by the best government Chinese money can buy
Puck da guns - ban Politicians!!!!!
Robert Harris <bob at bobthecomputerguy.com>


-----Original Message-----
From:	Jim Davies [SMTP:jimd at vcc.bc.ca]
Sent:	Friday, October 31, 1997 9:12 AM
To:	diy_efi at coulomb.eng.ohio-state.edu
Subject:	Re: fuel filter fittings



On Fri, 31 Oct 1997, Tom Cloud wrote:

> worked on anyway).  The tubing was SS, about 1/4" in diameter with
> a pinhole sized i.d.  Many of the fittings were compression!
>
> Very few of the tubing fittings we used were flare -- and they
> were the ones to give problems.  Based on my experience and from
> what I see at Home Desperate, et al, it looks to me that it's like
> crimp electrical fittings or any number of other things -- it's
> the quality of the part.

Agreed. If it says "Weatherhead" on it, use it, otherwise forget it. IMO,
of course. As for flare vs compression fittings, workmanship is an
important factor, along with brand used. Here is my thinking on it, based
on my experience.

1) either will work, in the pressure ranges of interest here.
2) a double flare takes a bit of skill to do properly, and if faulty will
leak.
3) a compression fitting takes a bit of skill to do, especially being sure
the tube end is straight for the necessary length, the tube cutter was
used properly (and was of decent quality) and the compression union is not
overtorqued. If this is done correctly, it is a suitable joint. If done
badly, it will leak. If done semi-badly, it will leak LATER. It will fail
due to vibration, the nut which is very thin, may split lengthwise or
tubing problems related to its hardness may appear.
4) To me, the word "later" is the problem. Don't know about others, but
I prefer to spend the time and money necessary to do something properly,
and then forget about it. YMMV.

Jim Davies