Re: Repair of idiotic plastic pipe implementation on the Brewtus

On Mar 12, 3:53 pm, "Jack Denver" <nunuv...@xxxxxxxxxxxx> wrote:
Flaring plastic sound pretty lame. For that matter, using plastic to carry
hot water sounds lame also. How much would it have cost them at the factory
to use 6 inches of copper tubing for this line?

OTOH, a lot of home machines use nylon tubing with compression fittngs for
cold water. I've also used this tubing with compression fittings to run
water lines to filters, etc. I must say that it is easier to work with (more
flexible) than copper. The traditional compression fittings (which include
an extra metal insert when used with plastic) appear to work very well and
I've never had any leaks once they were tightened down. I can't say the
same thing for the "John Guest" quick connect type fittings which rely on a
o-ring for seal - it's only a matter of time befor the o-ring rots, while
compression gives a metal on metal seal that should be good for life once
tightened.

Flare tubing (in copper) is very common in the auto industry where it's used
for brake lines, etc. where pressures are extremely high. Again, if
properly done it's a leakproof metal on metal seal. I've never heard of
plastic being flared, probably for good reason.

As you say, the dealer should have tried another approach after the 2nd
failure. One definition of insanity is doing the same thing over and over
and expecting a different result.

"gscace" <gregory.sc...@xxxxxxxx> wrote in message

news:1173711590.574552.132720@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx



Hi:

A friend of mine was given a Brewtus that had been back to the Brewtus
dealer 4 times for repair of the plastic pipe connecting the feedwater
preheat (in the steam boiler) to the inlet connection to the brew
boiler. The manufacturer uses a plastic pipe, which appears to end in
a flare of some sort. The flared tube fits over an internal ferrule
in the fitting to which the plastic tube is attached. The flare is
captured by a nut that compresses the flare against a sealing surface
on the fitting. The design seems pretty sketchy to me because the nut
imparts compressive load to a pretty thin flare. There's gotta be
stress concentration in the corner of the flare, and in fact the
failure of the tube occurred precisely at that point.

I discovered that 1/4 inch copper refrigeration tubing fits over the
internal ferrule just about perfectly. I also discovered that a
standard SAE flaring tool made a flare that fit the internal
dimensions of the nut just about perfectly as well. The nut itself
needed the hole diameter opened up from 6mm to slightly over 1/4 inch
(I used a letter F drill, which is .257" diameter). The hole should
prolly get chamfered on the inside by a countersink.

We replaced the plastic piece of feces with copper refrigeration
tubing. The system was leak tight immediately. We then fired up the
machine for an hour to look for leaks. Finding none, we covered its
nether parts with stainless steel clothing and celebrated our
adventure by making coffee.

I do have to say that the service guys at the Brewtus dealer deserve
to get called out on this. The part is pretty lame to begin with, but
it's really inexcusable for that machine to have gone back 4 times for
the same repair. They are pros who I'm sure have seen this problem
before on other machines. Perhaps they have something to add here
that would help folks have confidence in their commitment to customer
service?

Oh, by the way, I liked the coffee it made. Functionally it's pretty
solid, but it could use more steam power. It's very easy to use.

-Greg- Hide quoted text -

- Show quoted text -
The high pressure plastic tube in the machine. Again this stuff works
very well indeed,
no problem there....but if during assembly they (Expobar) over tighten
the fittings, it can
"tear" the self formed flange at the end of the tube and cause it to
leak, or pop out of its
holder. However, one of the easiest fixes in the industry. If you come
up against
a leaky high pressure plastic tube joint, simply undo it, trim of 1mm
of the tube
(the self formed flange bit, you will probably see the tear), replace
on the fitting
and retighten. As you tighten the fitting will reshape (cold form) the
end of the
tube and it autoimatically forms it's own seal. Just don't overtighten
it (no
thread sealants of any kind are needed, or should be used).

Above taken from my OPV article, if the dealer had done the work
correcctly he would not have had the same problem 4 times over. This
stuff is used in the QM Andreja Premium (and some Isomacs) with no
problems and is ideally suited to the temperatures and pressures
involved. It is also used in non espresso machine applications has
many advantages.

1. Chemical resistance
2. Flexibility (especially when a loop is incoporated)
3. long life
4. Very cheap and easy to replace

But prehaps not ideal for the "ham fisted" engineer


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