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Topic: Brewing Pressure Gauge Problem? (31 msgs / 593 lines)
1) From: Robert Joslin
Hello Listers
     I've got a quick question for those of you more knowledgable about the
guts of an espresso machine than I am (that would be just about all of
you!).  My Andreja Premium is about 20 months old and recently I have
noticed when pulling shots that the brewing pressure gauge oscillates about
the pressure reading at roughly the same frequency as the pump....a blur
really.  This doesn't seem to affect the operation of the machine, but it is
a definite change from the way the gauge used to read and I don't really
know exactly when it began doing this.  Overall, I would say that the
machine has had light use over these last 20 months (avg. of a dozen shots a
month....OK, very light use)  and I have always been very fastidious about
cleaning and backflushing.  I have done perhaps 6 cleaning backflush
procedures in that time.  My question to the list is:  *Does this represent
a problem, a potential problem, or something that I can ignore for now?  If
anyone recognizes the cause of the problem,  would an explanation be brief
enough to post here?  *Appreciate your help.  Thanks.  Josh

2) From: Brett Mason
try descaling the whole machine - the pressure gauge is in the line
coming from the tank to the group head, and any scale in one part will
affect the other parts.  Back flushing doesn't affect much, just the
grouphead and valve....
Brett
  RWA
On 2/25/07, Robert Joslin  wrote:
<Snip>
-- 
Cheers,
Bretthttp://homeroast.freeservers.com

3) From: Robert Joslin
Brett
      You were the ONE person I was hoping to hear from.  Thanks for the
info.  Please don't go on vacation for the next few days!! :)  Josh
On 2/25/07, Brett Mason  wrote:
<Snip>

4) From: Brett Mason
I am a hacker only...  If you hear from Les, Mike (any of them), Ray,
Peter, Gary, Eddie, Ginny, and frankly many others, you'll get better
info...  But on this topic I think this is your issue...
mytwocentsonly
Brett
  RWA
On 2/25/07, Robert Joslin  wrote:
<Snip>
-- 
Cheers,
Bretthttp://homeroast.freeservers.com

5) From: Aaron
Not having one of these machines,but seeing similar problems in many 
pieces of equipment, im thinking either the line is restricted somehow, 
ie a clump of crap in it, or if there is some sort of dampening orifice 
feeding the gauge, and it's now wide open.
TO the gauge, dampening would be a plus, it'd dampen out oscillations 
like that
TO the spray head, a clog or restriction would be a NOT good thing and 
would very easily show on the gauge like that every time the pump 
strokes because the water can't get out as fast as it should hence the 
pressure build up until it does get out or the pump goes off the power 
stroke.
Ill second the notion that a good cleaning / flushing should hopefully 
fix this one.  I doubt your boiler has been in use long enough to 
produce clinkers (ok so it's NOT the fireside) but a lump of scale 
breaking loose and flowing downstream can easily cause probs.
I have a steam toy I used to use and notice that scale builds up if I 
don't use it for a few months, or didnt use it.  the little bit of water 
left in it in contact with the aluminum boiler would cause all sorts of 
nice things to happen... since you said your use is limited it's also 
possible, also what kind of water you put in it, is it tap water, if so, 
how hard is your water??
aaron

6) From: raymanowen
The pressure pulsations are from the vibe pump and being read by the gauge.
This will wear out the gauge. It will wear to the point that the gauge
pointer will no longer track minor variations in pressure. This hysteresis
or "lazy" response can never be adjusted out of the gauge.
It's a very good idea to give the machine a Depot Level cleaning, but
contact the repair depot to get their input.
NO! You Don't Have To Send It In, unless it has a 24mo warranty! Any tech
worth his salt can troubleshoot over the phone if your descriptions are
precise and accurate.
You have a practically unused machine. Standing water in the plumbing has
caused your grief, I suspect. Give it a shot, Josh.
My Captain Morgan cowboy brew is a real distraction right now!
Cheers -RayO, aka Opa!

7) From: Peter Zulkowski
It sounds like there is a solid column of water leading into the gage.
If there were some air in the gage, and/or in the line to the gage, this 
would tend to dampen the rapid movements and still give an accurate reading.
Try removing the gage and shaking the water out of it and draining the 
line at the same time.
Just an idea.
Please let us know what the fix is.
PeterZ
Suffering with Gout, here in LHC.
raymanowen wrote:
<Snip>

8) From: Brett Mason
Ouch Peter - that hurts...  Anything you can do for it?
Brett
  RWA
On 2/25/07, Peter Zulkowski  wrote:
<Snip>
-- 
Cheers,
Bretthttp://homeroast.freeservers.com

9) From: Mark J Bergh
This is a multi-part message in MIME format.
Hi Josh,
I also have a Andreja Premium that is just over two years old and have
encountered the same problem you describe.  Descaling does not seem to help
nor is effective as the capillary tube leading to the pressure gauge does
not circulate or flow and therefore is not easily cleaned if, in fact, it is
a problem.  I don't remember when my gauge began it's rapid fluctuations but
it seems I endured it for a long time before searching for a cure.  Chris'
Coffee, who I purchased the machine from, had the fix: a new gauge kit with
a much longer capillary tube.  The install was easy and painless and the
longer capillary tube was neatly coiled to lay against the insulation of the
boiler.  The longer tubing dampens the Vibe pump pressure output variations
to give a more stable gauge reading.  Haven't had a problem since installing
the replacement gauge.  Some do-it-yourselfers may want to find the correct
tubing and couple or solder an extended length to the existing gauge tubing
for the fix.  Personally, I think the cost of  replacement was not too
painful.
I have been through several other repairs and upgrades on my Premium you
might be interested in that you will probably encounter in the near future
if not already.  Contact me off-list if you are interested in those things.
 
MJB  
From: homeroast-admin
[mailto:homeroast-admin] On Behalf Of Robert Joslin
Sent: Sunday, February 25, 2007 2:17 PM
To: homeroast
Subject: +Brewing Pressure Gauge Problem?
Hello Listers
     I've got a quick question for those of you more knowledgable about the
guts of an espresso machine than I am (that would be just about all of
you!).  My Andreja Premium is about 20 months old and recently I have
noticed when pulling shots that the brewing pressure gauge oscillates about
the pressure reading at roughly the same frequency as the pump....a blur
really.  This doesn't seem to affect the operation of the machine, but it is
a definite change from the way the gauge used to read and I don't really
know exactly when it began doing this.  Overall, I would say that the
machine has had light use over these last 20 months (avg. of a dozen shots a
month....OK, very light use)  and I have always been very fastidious about
cleaning and backflushing.  I have done perhaps 6 cleaning backflush
procedures in that time.  My question to the list is:  Does this represent a
problem, a potential problem, or something that I can ignore for now?  If
anyone recognizes the cause of the problem,  would an explanation be brief
enough to post here?  Appreciate your help.  Thanks.  Josh 

10) From: Aaron
I wonder why nobody has come up with a tiny centrifugal pump yet, it 
would pretty much end all this oscillation / vibration problem.  or a 
tiny PD pump, sliding vane or something with a little unloader back to 
the boiler... or even a little air compressor, pump up the chamber with 
air pressure and use that to drive the water out.  ahh the ideas are 
endless for someone who tinkers.
aaron

11) From: raymanowen
I don't know the exact difference between liquid pressure gauges and gas
pressure gauges. Pressure is pressure, you'd think, but the gauges are
specified differently.
Momento-
Maybe bellows in some very lo pressure gas gauges vs Bourdon tube gauges
which I used to zero and calibrate for Cat research 45 years ago.
Gotta gig- gotta run.
Cheers -RayO, aka Opa!

12) From: miKe mcKoffee
Rotary pump espresso machines do not have pressure oscillation problem. 
Kona Kurmudgeon miKe mcKoffee
URL to Rosto mods, FrankenFormer, some recipes etc:http://mdmint.home.comcast.net/coffee/Rosto_mod.htmUltimately the quest for Koffee Nirvana is a solitary path. To know I must
first not know. And in knowing know I know not. Each Personal enlightenment
found exploring the many divergent foot steps of Those who have gone before.
Sweet Maria's List - Searchable Archiveshttp://themeyers.org/HomeRoast/
 
<Snip>

13) From: Robert Joslin
Dear Listers
     Thanks to all for your input.  Having done a little more homework and a
phone call or two I am convinced (as Mark Burgh has suggested) that the
problem is with the thin copper tube that leads to the brewing pressure
gauge.  Apparently the tubing is not long enough or coiled enough to to
dampen output  from the vibratory pump.  Exactly why it began to act this
way after some months is still a question.  Perhaps some change in the
dynamic of the pump.  I have photos of the actual changeout of the capillary
tube from a blog called espresso passione, so I think it is something I can
manage.  Thanks again to all of you.  What a neat group of folks!!
Josh
On 2/26/07, miKe mcKoffee  wrote:
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14) From: Michael Dhabolt
Josh,
As Peter has recommended, If you remove the existing capillary, blow it dry
and re-install it while making sure it is not filled with water during the
re-install.......it may solve the problem.  Tighten the fitting at the gauge
end just a bit tighter than it was originally.  frequently the vibration
dampening compressible air leaks off from the capillary after time.....as
soon as everything is solid (hydraulic) the vibration from the vibratory
pump is transmitted to the gauge.
Mike (just plain)

15) From: Rich
The hot water will adsorb the air over time and the syphon tube will go solid.  This will turn into a 
periodic maintenance item.  Other than the non standard fittings you are dealing with the best / 
cheapest / lowest repeat labor option is to replace the gauge with a liquid filled gage.  They neatly damp 
out these little pulsations.  Something like a $10.00 bill.
On Mon, 26 Feb 2007 11:16:54 -0800, Michael Dhabolt wrote:
<Snip>
making sure it is not filled with water during the re-install.......it may solve the problem.  Tighten the 
fitting at the gauge end just a bit tighter than it was originally.  frequently the vibration dampening 
compressible air leaks off from the capillary after time.....as soon as everything is solid (hydraulic) the 
vibration from the vibratory pump is transmitted to the gauge. 
<Snip>

16) From: Robert Joslin
Michael, Rich & Peter
     Of course!  Any gas/liquid interface that is not in a permanently
closed system will see continuing absorption of the gas by the liquid.  I
just assumed the gauge was liquid damped, had somehow gotten a little air in
the tubing and the compressable air was causing the oscillation by some
quirky resonance with the pump frequency.  Guess I was 180 out.  That would
certainly explain why the problem developed.  Thanks for the
explanation guys.  I'll let you know how it turns out.
On 2/26/07, Rich  wrote:
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17) From: Robert Joslin
Mike
     Is this a problem with all vibratory pump machines?
On 2/26/07, miKe mcKoffee  wrote:
<Snip>

18) From: Rich
I am referring to the gauge its self being replaced with one that is liquid filled, in the case.  Draining 
the syphon tube will minimize the pulsations but not eliminate them.  This URL will take you to a low 
cost surplus site where you can check out liquid filled gauges.http://www.surpluscenter.com/sort.asp?numrec8&sort=1&keyword
GL&catname=hydraulic&UID 07022614503145
It is broken into 2 parts, so cut and paste time....  These gauges are the hot setup for hydraulic 
equipment. And, I might add espresso machines.
--Original Message Text---
From: Robert Joslin
Date: Mon, 26 Feb 2007 14:25:57 -0600
Michael, Rich & Peter
     Of course!  Any gas/liquid interface that is not in a permanently closed system will see continuing 
absorption of the gas by the liquid.  I just assumed the gauge was liquid damped, had somehow gotten 
a little air in the tubing and the compressable air was causing the oscillation by some quirky 
resonance with the pump frequency.  Guess I was 180 out.  That would certainly explain why the 
problem developed.  Thanks for the explanation guys.  I'll let you know how it turns out.  
On 2/26/07, Rich  wrote: The hot water will adsorb the air over time and the 
syphon tube will go solid.  This will turn into a
periodic maintenance item.  Other than the non standard fittings you are dealing with the best / 
cheapest / lowest repeat labor option is to replace the gauge with a liquid filled gage.  They neatly 
damp
out these little pulsations.  Something like a $10.00 bill.
On Mon, 26 Feb 2007 11:16:54 -0800, Michael Dhabolt wrote: 
<Snip>
<Snip>
making sure it is not filled with water during the re-install.......it may solve the problem.  Tighten the 
fitting at the gauge end just a bit tighter than it was originally.  frequently the vibration dampening
compressible air leaks off from the capillary after time.....as soon as everything is solid (hydraulic) the
vibration from the vibratory pump is transmitted to the gauge.
<Snip>

19) From: Robert Joslin
Rich
     I understood what you were saying. I should have replied to each
post individually.  Thanks for the info and the link.  A pretty neat site.
Now if I can just mic the gauge case and figure out how to convert
kilopaschals to psi.......;)
On 2/26/07, Rich  wrote:
<Snip>

20) From: Rich
I just happen to have a very important book of useless facts.
Kilopascal X .145038 = pounds/sq in
or 100 Kilopascal = 14.5 psi
Hope that helps.  The big trick will be getting some type of adapter to the 1/8 ip fitting on the 
replacement gauge.  Probably a cut and silver braze job. 
On Mon, 26 Feb 2007 19:42:59 -0600, Robert Joslin wrote:
<Snip>
info and the link.  A pretty neat site.  Now if I can just mic the gauge case and figure out how to convert 
kilopaschals to psi.......;)

21) From: Leo Zick
Why not just buy a gauge with the right fitting?

22) From: Rich
If it is one of the european thread patterns it will cost a mint and not be liquid filled.  It will be much 
simpler to preform a little surgery on the tubing.  Cheaper also.
On Mon, 26 Feb 2007 21:06:29 -0500, Leo Zick wrote:
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<Snip>http://sweetmarias.com/maillistinfo.html#personalsettings

23) From: Michael Dhabolt
Gauge tubing adapters are generally available at auto parts stores, adapting
european and U.S. gauges to and from cars is common.
Mike (just plain)

24) From: Rich
The common adapters will couple from standard iron pipe thread (what is on most American made 
gauges) to metric.  If you end up with the existing fitting being one of the British thread patterns then 
you will have a problem.  And, looks are deceiving.  Hot water / steam at 130 psi will strip flesh right to 
the bone in a big hurry.  It pays to study the fitup carefully.
--Original Message Text---
From: Michael Dhabolt
Date: Mon, 26 Feb 2007 18:42:26 -0800
Gauge tubing adapters are generally available at auto parts stores, adapting european and U.S. gauges 
to and from cars is common.
Mike (just plain)

25) From: Dave
Everybody's favorite query/search site;-) will do all kinds of conversions
just enter what you want converted in the search box, for instance:
12 kilopascals in psi
or:
30 mph in furlongs per fortnight
-- 
Dave
Some days...
It's just not worth chewing through the leather straps
On 2/26/07, Robert Joslin  wrote:
<Snip>

26) From: RK
This is a multi-part message in MIME format.
Mark hit the nail on the head. a longer tube will fix the problem, I had =
one at one time and it did the same thing you described but only 2 =
months old when it happened, and Chris sent me a longer tubing and it =
did the trick.
Give chris a call and ask for Roger, he will know just what your talking =
about and send you a new tube.
RK

27) From: Aaron
which begs me to ask.... obviously this longer tube needed is a well 
known problem... since several folks mentioned it and hinted that they 
had this problem.... some time ago...
why the hell doesn't the manufacturer spend the extra dollar or so it 
would cost for them. to make the things with the longer tube in the 
first place??... has anyone made feedback to them concerning this?
Id be interested to know if they are aware of this problem and have 
either said deal with it, or we don't plan on fixing it,... or even. ooh 
no we didn't know, thank you for telling us... etc etc.
Aaron

28) From: RK
<Snip>
I'm not sure but beleive that these fixes are installed on the next 
manufacturing run, and untill that they are handled as they occur as you 
read that on some of the machines it took as much as 2 years to show up but 
on my machine it only took 2 months, mind you this has been well over a year 
ago for me.
This is only a guess and with some experience on production runs, it depends 
on the number of machines that were made on that production run before 
finding that this was a problem. In subsequet runs I would think it was 
taked care of, but only Chris at Chris coffee could answer that for sure
RK

29) From: Rich
If you look at the piece of tubing that connects between the gauge and a steam boiler you will see that it 
exits the boiler and then drops straight down for a distance, followed by a 360 degree loop and then 
heads back up to the gauge.  Not also that the gauge is located totally above the point where the tube 
first exits the boiler.  This is also the proper configuration for a hot water boiler.  If you want to use less 
tubing then you have to use a liquid filled (damped) gauge.  Even with the damped gauge you should 
have at least a 180 degree loop, "U" shaped tube.  Boiler 101
Rich
On Wed, 28 Feb 2007 20:20:36 -0500, Aaron wrote:
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<Snip>http://sweetmarias.com/maillistinfo.html#personalsettings

30) From: Demian Ebert
My two cents worth on this: My Andreja did the same thing. It never seemed
to have any impact on the espresso, but made telling where the pressure was
set a challenge. It never vibrated much when backflushing, so something
about the difference with grounds was important. I just ignored it and kept
on going. When we moved a couple of months ago, I drained the boiler
completely before packing. When we unpacked and started the machine, it was
noticeably quieter (pump noise) and the vibration in the pressure gauge was
gone. Perhaps there was an air bubble in the system somewhere that was
dislodged during draining and transport, I'll never know.
Demian

31) From: raymanowen
Demian,
Whenever a pump has to draw a liquid against an air lock instead of being
"force fed" a solid liquid column, the pump will cavitate and suffer damage
if the cavitation is allowed to continue. Ultrasonic cleaners use the
principle of cavitation of the surfactant or cleanser against the solid
article to be cleaned.
The result is microscopic explosions and implosions of the liquid. Abrasive
cleaning without the abrasive grit. Dental hygienists, take note- you can be
replaced by a user-operated machine. To wit: the Oral B SoniCare...
Cheers -RayO, aka Opa!
Brusha brusha brusha-


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