Has anyone tried replacing the vibe pump on the Rituale with a rotary one?
I openly admit that I have never laid eyes on a rotary pump, and don't
know if this is a technical impossibility, but it would be a cool mod if
it were possible.
-=Tucker

On Sun, 18 Apr 2004 12:02:21 -0700, Tucker Bradford

I don't think it would fit into the case, since the tank, which would
be removed, doesn't have the same shape as the pump, and there's no
large cavities elsewhere. No problem at all if you keep the pump under
the counter.

--
Jim

(jim_schul...@ameritech.net)

No room for a Procon 1/6Hp pump. It will BARELY fit in a Millenium I'm told.  Here is my retrofit. I have since installed a check valve (between the needle valve and the elbow below) when the pump's internal one failed. I no longer use the needle valve as a gicluer, but run it wide open.

http://www.claycritters.com/coffee/isomac_millenium_pump_retrofit.htm

Dan

news:pan.2004.04.18.19.02.21.402545@mygenes.removeme.net...

To which I would respond, why bother?  I used to be convinced that rotary
pumps produced better results than vibes.  Now that Jim Schulman and I had
the chance to compare two nearly identical Cimbali Jrs. in a
somewhat-controlled test of a vibe version vs. a rotary version (which we
wrote up on a.c. a couple of weeks ago), we could not tell the difference.
Not only did we do our best in comparing the output of the two machines in a
singled blinded test, we had lots of opportunities to use both machines
during Jim's 4 day visit.  We were compelled to use the vibe exclusively
for some of this time because the rotary was down for retrofitting with a
PID controller.

Neither of us seemed to mind a bit being forced to use the vibe machine.

I think your time, effort, and money could be put to much better use than
retrofitting this machine from vibe to rotary.

Just my take.

ken

a slight addendum -- something I omitted in this post last night; you need
to be sure the pressure bypass valve on your vibe pump is properly set at
about 9 bar.  If not, then in an unregulated vibe pump you can get very
erratic pressures with the pressure topping out around 14 or 15 bar.  In
that setting the results from the vibe pump WILL be inferior to a properly
regulated rotary pump.

ken

news:1086pbdi41l32b3@corp.supernews.com...

Of course, we should note that "YMMV"  and that "two observation doth
not a conclusion make."

ray m

news:f5a1d7ff.0404190735.78497305@posting.google.com...
<news:1086pbdi41l32b3@corp.supernews.com>...

YMMV= "Just my take"  (see above)

I should add that I was convinced for almost a year that the rotary machine
made better espressos than the vibe, and when Jim S. visited me right after
I got the rotary machine, in April of 2003, he was convinced that the rotary
produced shots had a reddish brown color unlike what he had seen coming out
of vibe machines.  Shortly after Jim's 2003 visit I used a
non-coffee-conoisseur friend as a guinea pig in the first Jr. vibe vs.
rotary test I've done, and the reddish color aspect of the rotary shots
proved not to be reproducible.  The impression from this first test was that
the vibe produced somewhat inferior shots compared to the rotary.

So, Jim and I both had a pre-existing bias, at least a year ago, to believe
that rotary machines make better espressos.

When Jim came back to visit this year, we spent the better part of a morning
getting all adjustable variables of the two machines as close to identical
as possible, which was a significant difference from what I did a year ago
when I first ran this sort of test (due to ignorance on my part).  Once the
vibe pressure relief valve with bypass back into the water tank was set up
correctly, and once brew temps were equalized (not relying on the front
panel pressure guage but rather on in PF thermocouple readings), we could
not tell a difference between the output of the two machines.

This is to say that maybe you can tell a difference, but we sure can't.  If
I were in a good cafe with both properly adjusted vibe and rotary machines,
and if they asked me to pay 5 cents extra for the rotary produced drink, I
would take the vibe drink.

ken

On 19 Apr 2004 08:35:47 -0700, Ray_Ma...@hotmail.com (Ray) wrote:

It's two more observation than support the opposite conclusion.
Moreover there's additional tests that support the same conclusion:

1. Andy tested pressure variations extensively on rotaries, and I a
bit on vibes. Andy got no systematic taste differences on the rotary;
I got a slight improvement at lower pressures on the vibe.

2. When Ken and I adjusted the the vibe machine using an undamped
pressure guage, something very interesting showed up: The guage does
not jitter on the rotary. It jittered wildly on the vibe when the
pressure was topped out at 12 to 14 bar (i.e. the bypass wasn't doing
anything). These jitters diminished the more water the OPV bypassed,
and at 9 bar the needle was virtually steady (it started slightly
jittery and settled in a few seconds)

This leads to a very compelling theory that accounts for all the
evidence so far:

1. There's not all that much difference in espressos smoothly
extracted anywhere in the normal 8 to 10 bar range; pressure is less
critical than grind or temperature.

2. Close to their maximum pressure, vibe pumps indeed vibrate, i.e.
cause large transient pressure waves at the puck. As their pressure is
reduced with a bypass valve, the vibration diminishes. At around 9
bar, the behavior of the vibe becomes more or less identical to the
rotary's

3. So at 9 bar, there can be no systematic taste difference.

4. If the theory is correct, a rotary pump will pull a better 11 to 12
bar shot than a vibe, since the vibe will indeed vibrate at that
pressure.

--
Jim

(jim_schul...@ameritech.net)

I assume what is happening is that in a vibe in between strokes the pressure
in the system drops but not below 9 bar - the output without a bypass is a
sine wave varying from a peak of 14+ bar or so down to say 10 bar.   When
the piston goes on the return stroke the check valve prevent the water from
returning to the inflow but the pressure on the output side immediately
begins to fall from its peak of 14 bar. It does not drop to zero instantly
because the system as a whole is pressurized and the pressure can only leak
out slowly thru the puck (when no puck is present to provide resistance, the
pressure false quickly). But, in the presence of a puck, before pressure has
fallen very much, 1/60th of second later the next stroke begins and the
pressure heads up again to the next peak.

The overpressure valve is set to open at say 9 bar and thus places a ceiling
on pressure  - any fluctuations in the pressure over the set point
dissappear - the pressure could fluctuate from 9.1  to 12 or  from 10 to 16
and (within the limits of the OPV flow capacity)  only difference it would
make would be the volume of water heading back to the reservoir via the
bypass.  The pressure gauge and the puck no longer "see" any pressure
variations because all the variation is in the return line - if you put a
gauge on that, it would swing wildly from almost nothing up to say 5 bar at
60 hz.

We know that vane pumps have their own fluctuations, but they are almost
always factory equipped with an internal bypass which has the same effect as
the OPV on the vibe.

What vibes have been lacking all along is some sort of adjustable OPV with
bypass return. On my Oscar the expansion valve is preset at somewhere around
15 bar and to boot the output is directed to the drip tray so reducing the
pressure at which it opens it would waste a lot of water. The lack of
adjustable bypass and not the pump itself appears to be the culprit. Some
manufacturers have realized this and have started to factory equip their
vibe machines with bypasses that are adjustable or preset around 9 bar.  I
guess I'll have to improvise something for my Oscar.

news:h8c880h6dkpbsrjod2o56cq5u1gknmf9pm@4ax.com...

news:WISdnTSYcbR69RndRVn-gQ@comcast.com...

<snip>

this sounds vaguely pornographic --
:-)

On Mon, 19 Apr 2004 20:03:47 -0400, "Jack Denver"

I checked earlier this year, but the parts places don't sell some
generic version of the part.

I never figured out that the Isomac OPV was adjustable. Then the techs
at Chris coffee told me they could be adjusted by turning the shank
which held the exhaust tube -- yours may also have a similarly
disguised adjustment. In that case, it would just be a question of
running the hose back to the tank.

Alternatively, something like the spring adjustment Greg did on his
Silvia may work.

My thinking at this point is that one doesn't even need a pressure
guage to do the adjustment -- about 215cc/min flow rate equates to 8
to 10 bar pressure, so setting the bypass volume to this when running
against a blind filter should be in the ballpark.

See the pump curve at:

http://www.ulka.it/eng/E.htm#

In any case, without the bypass, one still gets the same effect
pulling 2 to 2.5 ounce doubles. Since this is a bit long, a really big
basket is advisable.

--
Jim

(jim_schul...@ameritech.net)

Of course there are other differences, which may or may not make a
difference to the OP. The rotary is unquestionably quieter, although
as you say it may be possible to ameliorate that some with better
insulation (if you can still get the heat out of the pump). The
rotary, with an appropriate gicleur, has a clear advantage if you want
to produce cafe crema, since most vibe pumps can't produce the
required flow while maintaining 9 bars pressure. And some people
prefer plumbed-in machines, myself among them, and I think that's
easier with a rotary pump.

Best,
    David

My IM came with an external bypass for its vibe pump. Not to be confused with the safety relief valve on the boiler that protects the system from over pressure.  The vibe has a 1/8" NPT outlet.  If one could find a 1/8" bypass valve it would be easy to install there on any machine without resorting to soldering. Dan

fyi:  Any regulating valve between the pump and the PF that returns water to the pump inlet or water tank (as opposed to dumping it) is best called a bypass valve instead of an overpressure valve. That's because it is regulating the system pressure by bypassing water back to the source. An OPV would be a valve that protects the system from, well, an over pressure condition. One would hope that it never had to work.

Most HX vibe machines have 2 types of  safety valve:

1. The steam safety valve mounted on the steam boiler.  This valve is preset
to open at some fairly low number  around 3 bar or so, so that if your Pstat
is set too high or sticks in the on position you don't create a bomb. In no
event should you interfere with or alter this valve. Due to the somewhat
flaky Pstats on Oscars I've had mine pop more than once. Once you get over
the initial shock, it's not that big a deal - it pops open,  a bunch of
steam shoots out for a second and once the overpressure has been relieved
the spring snaps shut again.

2. An expansion valve in the HX circuit. These are found in single boiler
machines also. Water is non-compressible and expands when hot. If the HX
circuit is  full when the machine is cold, tremendous pressure would be
created when the water expands on heating. These are usually present
somewhere in the 15 bar range and are the ones that can sometimes be
adjusted or hacked to a lower release setting to act as bypass valves for
pump pressure limiting purposes.

news:iW7hc.165676$gA5.1948515@attbi_s03...

My IM came with an external bypass for its vibe pump. Not to be confused
with the safety relief valve on the boiler that protects the system from
over pressure.  The vibe has a 1/8" NPT outlet.  If one could find a 1/8"
bypass valve it would be easy to install there on any machine without
resorting to soldering. Dan

fyi:  Any regulating valve between the pump and the PF that returns water to
the pump inlet or water tank (as opposed to dumping it) is best called a
bypass valve instead of an overpressure valve. That's because it is
regulating the system pressure by bypassing water back to the source. An OPV
would be a valve that protects the system from, well, an over pressure
condition. One would hope that it never had to work.

I looked at mine yesterday. It appears to have an adjustment at the
discharge side as you describe. However, turning it did not seem to make a
difference in the discharge against a blind filter. I got somewhere in the
vicinity of 240cc/min no matter what.

I'm not sure what model # Ulka the Oscar has, but it's the "big" one.
Remarkably noisy despite the rubber mounting, but it's hard to imagine how
you could fire a solenoid and a metal piston 60x / second and not make a
racket.

news:6ht8809at90jtqcqu82fervbfkfakcuri1@4ax.com...

On Fri, 23 Apr 2004 18:18:03 -0400, "Jack Denver"

That's a lot of water, and means it's around 8 to 9 bar

--
Jim

(jim_schul...@ameritech.net)

Do I read this right, that the Oscar has a pressure adjustment valve?
Do you just grip the part where the silicone tube is mounted and turn it
or what?

thx
afx

Yes, I'm guessing that turning this barrel changes the compression of the
spring than holds the expansion valve closed against pressure. It looks that
that is its function but again I wasn't able to actually effect a measurable
change in the amount the valve was bypassing. I have no gauge to measure
with.

news:c6dh6t$1dd7$1@marvin.muc.de...

I am busy with the kitchen renovation right now. If noone else tries it the
next two weeks, I'll check it out as soon as I do have a working kitchen again.
(I just received a PF pressure gauge for the WMF/cimbali cleanup projec).

thx
afx