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Thread: Water on top of firm Silvia puck

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    Water on top of firm Silvia puck

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Hi all,

    I just bought a Silvia and am experiencing something very strange with it. Basically I am putting in the right amount of coffee at the correct grind (I had mocopan grind me some coffee for the Silvia when I picked it up) and I get decent crema (the guiness effect) and shot timings (25 second pulls approx 30ml of coffee with the double basket)

    However, when I remove the portafilter from the grouphead, there is water sitting on top of the compressed coffee - despite the fact that the puck is firm and has a slight imprint of the screw that holds the shower screen in. If i bash out the puck it comes out in one solid piece so I know that my grind and tamp is basically ok. Even if I wait a few minutes before removing the portafilter there is still water on top of it.

    Also, I dont hear the solinoid valve bleed off excess pressure after pulling a shot - whereas with my dads HX machine after you switch off the espresso button you can hear and see the excess water and pressure come out the valve and into the drip tray. Is this normal silvia behaviour? I would have expected that after pulling a shot the excess pressure would be auidably discharged via the valve into the drip tray, and the puck would be dry.

    Any tips/comments/advice would be greatly appreciated!

    Thanks guys,
    Rob

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    Re: Water on top of firm Silvia puck

    Pull the cover of the drip tray off & watch the rear LHS of the drip tray ( about an inch in from the very LH corner) when you switch off the coffee button. If all is well the pressure relief will come out into the drip tray there.

    In any case with the Silvia you dont normally hear the same big gush of pressure relief that you do with a semi-commercial or commercial machine. Also if the pressure relief on your Silvia were not working, youd get a wrist full of hot burning coffee dregs blowing out of the group handle/filter when you go to release the handle.

    Water on the top of a correctly dosed puk can only mean one thing....coffee too fine...except that in your case you have mentioned you are only getting a +slight+ *imprint from the grub screw. That grub screw sticks down an awful long way, so if you are not also getting an imprint from the edgeing ring of the shower, then you are still basically underfilling your filter (even if only by a small amount...which would be the reason why the puk is firm enough)...in which case the wetness is probably caused by under dosing OR a combination of under dosing as well as coffee too fine.

    Hope this helps.

    Your supplier should be able to tell you this!

    Regardz,
    FC.

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    Re: Water on top of firm Silvia puck

    Thanks FC - I did wonder that if the pressure release valve wasnt working id get a coffee sneeze, and it never happened so I can only assume its fine.

    I think perhaps Mocopan did grind the sample coffee they gave me too finely, as it is VERY fine (2-3 clicks finer than what my dads HX requires when using his La Cimbali MD Domus grinder) and the shots I produced did taste a bit bitter.

    I ground some more beans on said Cimbali grinder at a slightly courser setting and found that the shot tasted better and had better colour and crema during extraction. The grind from Mocopan is producing a colour that I think is too blonde during extraction.

    I hesitated to overfill the portafilter because once or twice when i did add more coffee i had a very tough time getting it to lock into the grouphead, however I will play around with it again tonight. :D

    Thanks again,
    Rob

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    Re: Water on top of firm Silvia puck

    Hi,

    I used to get dry frim pucks everytime with the Mokita. The Silvia I have now does exactly as you described. I woulnt worry about it if I were you, so long as the puck comes out intact. You could let the portafilter drip for a few seconds and the water will be gone.

    Cheers

    franjae :)

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    Re: Water on top of firm Silvia puck

    Ihug007, You do realise you are doing some pretty severe ristrettos here: 30 mls from the double basket. If you like it that way (and many do) fine, but ordinarily a double basket should yield up to 60 mls in 25 to 30 secs.

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    Re: Water on top of firm Silvia puck

    Franjae, regardless of how long I leave the portafilter in the machine it always seems to come out with a pool of water on top... several millimetres deep.

    Robusto, I neglected to mention that I was using two shot glasses - one under each spout of the portafilter. So I was/am getting about 35ml in each shot glass over a 25s period and the coffee looks to be extracting correctly (colour and consistency look right). I messed around with it again last night and cannot for the life of me figure out why so much water is left on top after a so-called perfect extraction!! Very frustrating and quite messy.

    I can only conclude that the grind is too fine, since when I tried using pre-ground vacuum packed coffee from Safeway, after pulling the shot (all 70mls in 8 seconds ;D) and immediately removing the portafilter handle there was only a hint of water visible on top of the puck - it was negligible.

    Perhaps it has something to do with the tamping pressure? When using HX machines ive never been a fan of hard tamping (i.e. 15Kg tamps or more) but believe that as long as your grind is right, firm tamping is all thats required. Everyone seems to recommend a 15Kg (circa) tamp on forums like this though.

    Incidentally, when studying the water on top of my pucks, I can quite clearly see that there is a significant imprint in the puck from the grub screw that holds the shower screen, as well as a faint outline around the border of the puck presumably from the border of the shower screen.

    It seems as though some extra water is not being discharged via the 3-way solenoid after extraction, and perhaps this explains the residual water? I wonder if a problem like this can rectify itself once the components are run in.

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    Re: Water on top of firm Silvia puck

    Thankfully my Silvia produces dry pucks, but I do tend to over-fill the double basket with aproximately 20 grams of finely-ground fresh, home-roasted coffee. As long as its not tamped too hard, and the portafilter screws on without effort, good expressos are produced with a dry puck.

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    Re: Water on top of firm Silvia puck

    I had wet pucks on my Classic for a while. I think FC had the best diagnosis of the potential problem. Under dosing and a too fine grind. For ristrettos the brew pressure will be really high, unless youve done the pressure mod. With a high brew pressure you have to grind finer. When you grind finer the puck is less porous. Ultimately if youre under dosing and grinding too fine, youll find water on top of the puck.

    When I had my Silvia, and ran a direct comparison with my Classic, I found I had to grind finer for the Silvia. I attribute that to the higher brewing pressure, as I had adjusted my Classic down to the 9 bar mark, whereas that stock Silvia is supposed to brew up to 12 bar.

    Otherwise, when I had wet pucks on my Classic, it was a symptom of under dosing.

    Regards,

    Mark.

    One more thing. If youre not using fresh coffee, youll need to grind finer still. I have some old Vittoria coffee lying about and I have to grind that nearly 3 clicks finer on my MDF grinder. Thats a huge difference and the coffee comes out like talcum powder, yet it only just satisfies the 25-30 sec pour.... BTW: I dont drink that coffee, I use it to do temperature measurements, rather than waste good fresh coffee.

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    Re: Water on top of firm Silvia puck

    It sounds like your solenoid valve isnt working. Mind you if it is the valve not working it should be obvious in other ways. ie. pressure left in the portafilter. You should be able to hear it releasing the pressure and see liquid in the drip tray when you stop each shot.

    Grant

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    Re: Water on top of firm Silvia puck

    ihug007,

    When I pull a blank shot and I remove the portafilter, water in the basket sometimes just sit there and not drain out. Before anyone suggest that I should clean out the basket, I am talking a new basket here. Therefore when you add the grounds, I cant see how it would drain any quicker or better.

    I am curious about the "too fine grind" or "under loading" suggestions, so I will try these. The water on top of the pucks drains a few seconds after I remove the portafilter, so it is no big deal for me, except I get some drips on the counter !

    Cheers

    franjae

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    Re: Water on top of firm Silvia puck

    Franjae, sounds like were having an identical problem. I also found someone on coffeegeek forums with the same problem too. I may indeed be related to grind fineness however even if I run water through the portafilter empty as you described, it still has water sitting in it too - just as you described!

    My solenoid valve is definitely working as I can observe some excess water getting released into the drip tray, however I was wondering if its been set too high in the sense that it requires too much pressure in order for it to activate and that could explain why I have some residual water on top of my puck. Under this theory, the bulk of the water is dissipated through the valve correctly immediately after the shot is stopped, however as the bulk of the water is dissipated there is some remaining under less pressure - not enough pressure to dissipate via said valve. I wish I could make some adjustment that would change the pressure sensitivity level at which the valve is opened.

    One thing is for sure, im definitely NOT under loading the portafilter. If i put any more coffee in I cant even get it to lock into the group head. Also, the pucks themselves are ok - firm and with an imprint from the showerscreen and grub screw. They just have several mls of water on top thats all. For some reason this annoys me greatly. Just feel like for $650 I should be getting something that works correctly....

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    Re: Water on top of firm Silvia puck

    Well, I just recently purchased my Silvia and was getting poor shots. Although my puck was dry, I was getting no crema and very slow extraction.

    I went back to basics as described at http://www.coffeeco.com.au/articles/setup.html

    I did all the tests then made a brew using the following techniques

    http://www.boingboing.net/2005/08/09/espresso_crema_shots.html and
    http://www.coffeegeek.com/opinions/edgabrielle/09-15-2002

    Tonight I made my best latte yet. Deep rich crema bubbling up like Guiness.

    Interestingly, my main mistake was too fine a grind. Based on internet reading I had adjusted my Rocky to +7 above "just touching" burrs. I now have the Rocky set to 16 which is +14 on my machines "zero". Still quite fine but obvioulsy pretty close to right.

    So whats the motto. Read all you can, then adjust your equipment to suit your coffee and your style.

    How much fun would it be if anyone could do it?

    Patmac likes this.

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    Re: Water on top of firm Silvia puck

    ihug007,

    I honestly dont think you need to worry about the solenoid valve. The water is simply not draining away quick enough. The seal may have something to do with it. Do you not notice that as soon as you release the pf, only then the water starts to drain out?

    I am going to grind my beans a little coarser tomorrow to see if that will make any difference and report back. Otherwise try another basket. I still believe that is the cause. Once water is in the basket, what else is going to make it drain out? Certainly not the solenoid valve. If it is not draining when the basket is empty, why would it drain when theres coffee in it????

    My 2 cents worth, heh-heh!!

    franjae :)

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    Re: Water on top of firm Silvia puck

    Franjae,
    I spent some more time last night (and a lot more coffee) playing around with this problem, and ve observed that roughly 50% of the time if i just run a blank shot through the protafilter and then immediately remove it from the grouphead, the water has completely drained away and the basket has no water left in it. The other 50% of the time, when i remove the portafilter handle from the grouphead their is about 3ml of water sitting in it, which only begins to drain once the handle has been removed from the grouphead. Strangely, every time i pull a shot with coffee in the basket, I am always left with water on top of the firm puck.

    This makes me think that the problem is actually to do with the balance of pressure in the system after pulling a shot (blank or otherwise). That is, there seems to be some issue that the not all of the excess water is being discharged through the solenoid valve, but is left sitting on top of the puck indefinantly since there is some type of pressue preventing it from draining through the puck (or basket in the case of a blank shot).

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    **UPDATE** Water on top of firm Silvia puck

    I just spoke to someone at Mocopan service centre. He said that this issue is most likely caused by the fact that the domestic Rancilio machines are set at around 11-12bar pump pressure in order to achieve the same results as a comericial machine but hence require a finer grind. He said that since they use a vibratory pump and not the adjustable type used in commericial machines, its likely that this extra pump pressure is the cause of the remaining water on top of the firm puck after extraction.

    Whilst I realise that the coffee extraction is not effected by this, I just wish there wasnt that water sitting there after the extraction! Oh well life goes on I guess. :-/

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    Re: Water on top of firm Silvia puck

    ihug007,

    I tried a coarser grind this morning and it does not appear to have made noticeable difference. As you said, the quality of the shot does not appear to be affected, so it is one of those things well have to accept and get used to. Otherwise we will be tempted to UPGRADE yet again !!! ;D

    Cheers

    franjae

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    Re: Water on top of firm Silvia puck

    I already AM tempted to upgrade and Ive only had my silvia 1 week! I do like it but I confess I was expecting it to behave more like an HX machine based on the reviews Id read. Nevertheless, I simply dont have the budget for and HX machine at this stage in life so I must get used to Miss Silvias quirks and move on....

    Regarding the courser grind - the only time I got a true dry puck was when using the prepacked vacuum sealed stuff from the supermarket. Its much too course though.

    In another post on coffeegeek about this issue, someone responded with detailed instructions on how to mod the pressure of the Silvia. Im not quite sure I want to go down that path yet but here it is for reference.

    http://mysite.wanadoo-members.co.uk/m4tt5mith/SilviaPressureMod.html

    As I said before, the Rancilio service guy told me the Silvia is around 11-12bar, and commerical machines are around 9 bar. I think he said something like they needed to be around 11bar because of the vibratory pump and also to get the commerical quality extractions. Im going to do some reading about this 9bar Silvia mod and see what i find out!

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    Re: Water on top of firm Silvia puck

    Quote Originally Posted by ihug007 link=1125276405/15#16 date=1125450096
    Regarding the courser grind - the only time I got a true dry puck was when using the prepacked vacuum sealed stuff from the supermarket. Its much too course though.
    Hi ihug007,

    Havent you got a grinder? A good quality grinder is an essential companion to a Silvia or any other quality espresso machine. Without that, youll always be p***ing into the wind trying to get acceptable quality shots.
    In another post on coffeegeek about this issue, someone responded with detailed instructions on how to mod the pressure of the Silvia. Im not quite sure I want to go down that path yet but here it is for reference.
    http://mysite.wanadoo-members.co.uk/m4tt5mith/SilviaPressureMod.html
    To get the best out of any espresso machine, you need to have the brew pressure in the right ballpark, i.e. 8-10 bar. With the correct grind and dose for your particular PF basket, you should be able to achieve this while following the "Golden Rule", which states.... 30ml single shot pulled in 25-27 seconds with 7-8 grams of coffee in the basket, or 60ml for a double using 14-16 grams of coffee in the same time.

    If the grind is too coarse the shot will pull too quickly, too fine and the pressure will build up to the limit of the pump or Pressure Limiting Valve (if fitted) and the shot will pull too slowly or stall the pump. Having a good quality grinder will allow you to fine tune the grind until the ideal is achieved.
    As I said before, the Rancilio service guy told me the Silvia is around 11-12bar, and commercial machines are around 9 bar. I think he said something like they needed to be around 11bar because of the vibratory pump and also to get the commercial quality extractions. Im going to do some reading about this 9bar Silvia mod and see what i find out!
    This sounds like a really strange thing for a certified Rancilio Tech to say. There are plenty of Commercial Single Group, Vibe Pump machines in service, in small cafes and the like and as far as I have been able to determine from research, these operate in no different a fashion to a "Plumbed-in" Rotary Pump multi-group machine. The normal operating brew pressure of all of them is nominally 9 bar.

    The mod to reduce the maximum system pressure of a Silvia is quite straight forward since it has an accessible Pressure Limiting Valve. If you like Ristrettos though, reducing the maximum system pressure to 9 bar will preclude your being able to pull this type of shot, since a Ristretto is meant to be pulled in the same length of time as a single or a double but with half the quantity of shot resulting. Makes for a very intense and flavoursome brew that quite a lot of coffee geeks and snobs aspire to making successfully.

    Hope this helps a little :D...

    Cheers,
    Mal.

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    Re: Water on top of firm Silvia puck

    The mod to reduce the maximum system pressure of a Silvia is quite straight forward since it has an accessible Pressure Limiting Valve. If you like Ristrettos though, reducing the maximum system pressure to 9 bar will preclude your being able to pull this type of shot, since a Ristretto is meant to be pulled in the same length of time as a single or a double but with half the quantity of shot resulting. Makes for a very intense and flavoursome brew that quite a lot of coffee geeks and snobs aspire to making successfully.
    I have my machine set to 8.5Bar and it does ristrettos beautifully. *Alan (Perth CS member) did one on my Bezzera to die for after 15 minutes experience on the machine (on our last cafe day). *Im not an expert on ristrettos but the group pressure for the shot doesnt seem to affect it much, well not at 8.5Bar anyway.

    I think it is just simply getting the grind right and also having good temperature profile so that the shot isnt burnt. *Burning shots seems to be a major issue on some machines as the flow rate is so low.

    Grant

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    Re: Water on top of firm Silvia puck

    This is interesting. So exactly why do they make the pump pressure in these little machines so high? there must be a good reason. The Rancilio service guy seemed to be struggling to give me an answer as to why water is left on top of the puck (which is firm) and thats when he came out with the remark about how its related to the extra pressure these little machines have etc... and how its required to produce the best quality shots.

    I have since research alt.coffee on google groups and there are heaps of other Silvia owners there with the same problem. Everyone seems to assume that people with this issue arent grinding/tamping right but its not true. Ive been invovled making coffee on commerical machines for years and I know what im doing.

    Anyway, I just had another thought. Perhaps slightly reducing the pump pressure would indeed resolve the water on top of puck issue. Maybe when these machines come out of Rancilio, the pump pressure is set simply within a range of say 10-12 bar. Perhaps people with the water on puck issue have received a machine that is around the 12bar mark??? Just an idea. Clutching at straws really.

    Regarding the grinder - when I bought the machine they ground me half a kilo specifically for the Silvia. Personally I think they ground it slightly too fine, but I may be wrong. I will be acquiring a La Cimbali MD Domus grinder tomorrow morning, and from that point on obviously Ill never need to get anything ground for me again. I also think ill be inclined to attempt my own roasting as well since I love the idea of absolute freshness.

    I dont want to derail this thread BUT can anyone recommend me any specific brand of popper? or should i go the heat-gun route?

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    Re: Water on top of firm Silvia puck

    The pumps used in the Silvia and most home machines is made by Ulka in Italy. These pumps have an interesting property that the flow rate is inversely proportional to the pressure experienced by the pump. It just so happens that these pumps provide around 9 bar for a flow corresponding to a double shot. So if you like making singles or ristrettos, where is the flow is nearly halved compared to a double, the pressure will be too high.

    The pressure mod on a Silvia is not as straight forward as most, as the SIlvia doesnt have an adjustable Over Pressure release Valve (OPV). Rather it is fixed at around 12 bar. The common modification to fix this is to unscrew the cap on the end of the OPV (to which the silicone return line is attached) and insert an additional washer and replace the cap. The additional washer will ensure that you cannot tighten the endcap to the original position. This will in turn relieve some of the spring tension holding the valve closed, meaning that it will open at a lower pressure. Scoring exactly 9 bar require a washer with a precise thickness. Some people have used compressable washers to give some adjustmant around the desired pressure.

    I hope that helps.

    Cheers,

    Mark.

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    Re: Water on top of firm Silvia puck

    Thanks Sparky, I dont think ill mod my Silvia just yet but Im glad ive at least got a bit more knowledge about it now!

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    Re: Water on top of firm Silvia puck

    Hi All,

    I think most of you are missing the point with respect to the purpose of a Pressure Limiting Valve or Over-Pressure Valve. Its purpose is to protect the pump and brew water circuit from excessive pressure, not limit the pressure at which you pull a shot.

    The only time that it is really warranted to start playing around with the PLV/OPV, is when your Brew Pressure is TOO LOW, which then prevents you from being able to extract everything good from the bean because the grind will probably be too coarse.

    Ulca Pumps are designed to withstand their rated pressure, usually 15 bar and up to 18 bar depending on the model. This is their rated safe operating pressure. Trying to achieve acceptable espresso shots by using the PLV/OPV to limit the system pressure to a nominal 9 bar means that you are probably not achieving the ideal grind size for your particular machine. You are better off leaving the PLV/OPV set to where the manufacturer put it and spend the time determining the ideal grind setting to achieve an ideal shot.

    A Ristretto, by the way, is a shot of espresso that is pulled in the same manner as for a Single or a Double shot, but only half the volume of espresso is collected in the same time.... defined here:- http://tinyurl.com/a2k4w
    As a consequence of pulling a Ristretto in the preferred, correct manner, it is an inevitability that the System Pressure will rise above that achieved for a "normal" shot. I guess you can always call a "Short Shot" a Ristretto by pulling the shot glass away before a full 30ml or 60ml shot is achieved but this is not in reality, a Ristretto.

    Cheers,
    Mal.

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    Re: Water on top of firm Silvia puck

    Mal:

    My machine has a rotary pump which evidently delivers consistent pressure over some range of flow rates, unlike the vibe pump. This has got to be a good thing.

    Sparky says that the vibe pump pressure will vary depending on flow rate with a double shot giving a pressure of a about 9 bar (on the Silivia) but a ristretto giving a higher pressure due to the reduced flow rate.

    On most machines adjusting this pressure can be a pain but on a commercial machine like the Bezzera 40P with a rotary pump it only takes a minute to make an adjustment. On most machines therefore you are not ever likely to bother making an adjustment.

    The other issue is the idea of it always being a pressure relief operation to protect the brew head. This may be the function of the OPV valve on the machines with a vibe pump. Again on my machine there is a suppression valve assembly which serves to protect the group head by venting excess pressure into the drip tray. The adjustment on the rotary pump is just a screw which seems to adjust both flow and pressure at the brew head although flow is controlled primarily by the use of a small orifice jet.

    It seems to me that although these machines have similar functions, they are designed quite differently.

    If you want to buy the best group pressure control then it seems that a rotary pump is the way to go which is why IF you have $2k+ for a prosumer machine then for not too much more you can get a commercial type machine with a rotary pump then it is worth it.

    Grant

    PS. I generally got dry pucks with the Silvia

  25. #25
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    Re: Water on top of firm Silvia puck

    Hi Grant,

    Yes, I fully understand the operation of so-called Rotary Pumps fitted to Prosumer machines and used under the counter by Commercial systems. I have an engineering background and a lot of experience with these and a lot of other designs.

    The term Rotary Pump is a generic description for a wide range of pump types and really only serves to distinguish this type of pump from a Vibe Pump (a misnomer really) which is in fact an Oscillating Armature Pump, but Vibe Pump is good. Most of the Rotary Pumps Ive seen fitted to up market machines are actually Eccentric Vane Pumps or Gear Pumps. All Rotary Pumps come under the the general heading of Positive Displacement Pumps, i.e. a fixed volume of a fluid is positively displaced from one position to another. A great description of the operation of such pumps is explained here...http://tinyurl.com/7j4ry.

    In the case of Rotary Pumps, to control the Output Flow Volume and thereby System Pressure, it is usually easiest to have a Discharge Bleed-Back Gallery cast into the casing of the pump itself so that discharge pressure can be controlled by venting some or all of the flow back to the Intake side of the Pump to prevent excess pressures developing... thats why you have this control device incorporated into the Rotary Pump on your machine.

    With all else being equal, i.e. ccomparing similarly rated pumps of different designs, all positive displacement pump discharge characteristics are very similar. It must be appreciated that fluids can not be compressed, therefore as a pump continues to operate in a closed system, the system pressure will continue to increase until such time as the pump housing fails, the driving motor fails or the system fails, hence the need for a method to control or limit the maximum system pressure. Positive Displacement Pumps are used in all large and small scale hydraulic power systems such as those used to operate the various linkages on a back-hoe for example.

    The pressure characteristics of a Positive Displacement Pump are therefore not really dictated by the pump as such, but by the system into which the pump is delivering the fluid. In the case of an Espresso Machine, this should be the Coffee Puck or Cake, not the PLV/OPV. The PLV/OPV is only there for the safety of the system and the user. The reason a Rotary Pump is not effected to the same degree as a Vibe Pump to the vagaries of system related flow variability (Normal Shot versus Ristretto for example), is that even the smallest Rotary Pump fitted to an Espresso Machine has significantly higher flow delivery capability than that of the largest Vibe Pump usually fitted.

    When its all said and done though, Owner/Operators should not tamper with the settings of the Pressure Limiting Devices fitted to their particular machines. It is a Safety Device and better left to personnel who fully understand the operation of such devices and the systems into which they have been installed. Like I said before, the only time you should even consider playing around with the PLV/OPV, is when the system pressure is being limited by the current setting of the device such that it is impossible to reach the desirable and nominal 9 bar of pressure. If this appears to be the case, then you should contact your supplier to have the machine setup by an appropriately trained technician.

    The Suppression Valve fitted to your machine Grant, is there to iron out any pressure spikes or troughs and thereby reduce stress on the system and components. It should also assist in achieving smoother water delivery to the Coffee Puck/Cake. The Orifice Jet you refer to is there to limit Total Flow in the event of an open system, e.g. when you flush water through the Group with the PF removed.

    All the best,
    Mal.

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    Re: Water on top of firm Silvia puck

    Mal:

    Yes, the rotary pumps are absolutely huge and as you say it is probably little wonder that they display better pressure versus flow behaviour than a vibe pump. They also cost ten times as much to build and possibly last ten times as long too going by the number of vibe pump failures that I have heard of.

    What they call the supression valve assmebly is a T-piece with an upstream valve in the water flow and a quite small spring to close it. The other part of the t goes to drain and has a similar valve but with a much more powerful spring. The one in the water path would also act as a non return valve and will also keep water under pressure in the hx. It looks very much like a pressure relief system to me in that if the water flow were stopped the pressure would eventually activate the flow to drain.

    It may be it has more than one purpose?

    I know the rotary pump adjustment will adjust the flow and the pressure at the same time.

    Anyway, certainly the rotary pumps allow easy adjustment and constant pressure.

    Grant

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    Re: Water on top of firm Silvia puck

    No worries Grant,

    I dont think Vibe Pumps are really made to last in the same way as a Rotary Pump.

    Even the smallest of Rotary Pumps is still an Industrial Quality Pump and as such, is designed to last a lifetime in a Domestic situation and be reliable in a Commercial situation. Vibe Pumps came along as an alternative for smaller consumer type machines to allow the price to be kept in the ballpark of the consumer. For 90% of consumers, this meets their needs more than adequately.

    Rotary Pumps do require maintenance though as the rotating parts do wear, so it would probably be a good idea to have them checked out by a techie every couple of years, rather than to react to a sudden and possibly catastrophic failure. Such inspections by a qualified person wouldnt be all that expensive and represent excellent insurance towards trouble-free longevity. Other than that, they are an extremely reliable piece of hardware.

    Cheers Grant,

    Mal.

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    Re: Water on top of firm Silvia puck

    Mal:

    I have read in one article that they are not to be dissembled and dont require regular maintenance.

    If Im wrong then that is OK but it is just that I am getting conflicting advice.

    I would have thought that they should be left alone unless they are leaking or making abnormal noises.

    Grant

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    Re: Water on top of firm Silvia puck

    Hi again Grant,

    Maintenance is only required in the sense that Ive referred to it above. Every couple of years in a domestic situation it would make good sense to have a qualified tech carry out an inspection to ensure that any developing problem is not missed. In a commercial environment, this type of inspection would probably be undertaken after a prescribed number of operating hours or x number of months equating to that number of hours.

    I wouldnt recommend that a user/owner starts playing around with the innards of their pump or motor but one inspection every couple of years by a qualified person is surely not over the top? :-?,

    Mal.

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    Re: Water on top of firm Silvia puck

    Mal:

    I think your advice on the point of rotary pump maintenance is wrong!

    I have cut and pasted this from a site containing information on Procon rotary pumps.

    I appreciate that you gave the advice in good faith but these pumps are all designed differently. *Certainly te Procon pumps are designed to be left until they do fail and that is the advice I have received previously.

    Regards,
    Grant


    Procon pumps are maintenance free, and internal bearings, vanes, and liner are made from special carbon graphite material which is self-lubricating, heat-resistant and chemically inert. *Housings and internal metal parts are 303 stainless steel. *These materials and PROCONs unique design features provide for no metal-to-metal contact resulting in a quiet, non-pulsating and dependable operation. *A mechanical rotary shaft seal and an external pre-lubricated ball bearing add to the rugged construction and long life.

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    Re: Water on top of firm Silvia puck

    Im not sure I agree with you Mal. The extraction of espresso is best done at a pressure of between 8 and 10 bar according to the Italians. This is not possible using a standard Ulka pump (an EP5 say) for single or ristretto shots, where the flow rate will correspond to pressure of up to 12 bar. So using the pump characteristics along with the coffee puck, you would only expect double shots to be extracted in the 9 bar pressure regime.

    The use of the OPV to pressure limit home espresso machines has been established for quite a few years now. For instance the Silvia pressure mod was first documented on alt.coffee in 1999 and has subsequently been adopted by hundreds of paople around the world. Similarly, I have adjusted the maximum pressure of my Classic down with quite palpable results for ristrettos and singles. In fact this was one of the most significant differences between the Classic and Silvia shots, observed when I had the two machines running together for a week. The lower pressure enabled a coarser grind and these shots had a thicker longer lasting crema and a creamier mouthfeel.

    I dont mean to start a war, but this is my experience.

    Regards,

    Mark.

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    Re: Water on top of firm Silvia puck

    Quote Originally Posted by wattgn link=1125276405/15#29 date=1125716833
    Mal:

    I think your advice on the point of rotary pump maintenance is wrong!

    I have cut and pasted this from a site containing information on Procon rotary pumps.

    I appreciate that you gave the advice in good faith but these pumps are all designed differently. Certainly te Procon pumps are designed to be left until they do fail and that is the advice I have received previously.

    Regards,
    Grant
    Hi Grant,

    I appreciate everything re the info you have supplied... thanks.

    Regarding inspections though, it is not necessary to disassemble a piece of hardware to determine if all is running as it should be. Im not sure what the experienced espresso machine techie would carry around in his tool kit, basically basing my comments on my experience and knowledge of more than 30 years in heavy industrial engineering, mineral processing, control and process systems and motor drive systems from fractional up to several thousand KW.

    If thats what Procon says about their equipment, well fair enough but Im afraid I dont hail from the era of "run it til it fails and then fit a new one"... have always believed, and still do, that an ounce of prevention is worth a pound of cure.

    All the best,
    Mal.

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    Re: Water on top of firm Silvia puck

    Quote Originally Posted by Sparky link=1125276405/30#30 date=1125838774
    Im not sure I agree with you Mal. The extraction of espresso is best done at a pressure of between 8 and 10 bar according to the Italians. This is not possible using a standard Ulka pump (an EP5 say) for single or ristretto shots, where the flow rate will correspond to pressure of up to 12 bar. So using the pump characteristics along with the coffee puck, you would only expect double shots to be extracted in the 9 bar pressure regime.

    The use of the OPV to pressure limit home espresso machines has been established for quite a few years now. For instance the Silvia pressure mod was first documented on alt.coffee in 1999 and has subsequently been adopted by hundreds of paople around the world. Similarly, I have adjusted the maximum pressure of my Classic down with quite palpable results for ristrettos and singles. In fact this was one of the most significant differences between the Classic and Silvia shots, observed when I had the two machines running together for a week. The lower pressure enabled a coarser grind and these shots had a thicker longer lasting crema and a creamier mouthfeel.

    I dont mean to start a war, but this is my experience.

    Regards,

    Mark.
    Heaven forbid Mark,

    No more wars please..... Im strictly a product of the 60s - make peace, not war. ;D

    Im not really sure what it is exactly, that you dont agree with me about. Ive read through your post a couple more times, gone over my own comments a couple more times too and we both seem to be saying more or less the same thing in different ways :-?

    Cheers,
    Mal.

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    Re: Water on top of firm Silvia puck

    Position 1: The OPV is to prevent over-pressure situations damaging the pump and/or equipment. The coffee puck should determine the extraction pressure and the OPV should be left at the factory preset.

    Position 2: The OPV can be set to limit the maximum operating pressure, so that near optimal extraction pressure can be achieved for a range different operating conditions (ie for single, double and ristretto shots). This generally means adjusting the OPV away from the factory preset.

    I am in the position 2 camp. Mal, I thought you were espousing the leave it alone, or position 1 camp (which did surprise me a bit).

    Sorry Mal, I am a product of the punk generation, where war seems more palatable *;) and even preferable *:-[ (just ask Bush Jnr ;D)

    Regards,

    Mark.

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    Re: Water on top of firm Silvia puck

    Quote Originally Posted by Mal link=1125276405/15#22 date=1125663121
    Hi All,

    I think most of you are missing the point with respect to the purpose of a Pressure Limiting Valve or Over-Pressure Valve. Its purpose is to protect the pump and brew water circuit from excessive pressure, not limit the pressure at which you pull a shot.

    The only time that it is really warranted to start playing around with the PLV/OPV, is when your Brew Pressure is TOO LOW, which then prevents you from being able to extract everything good from the bean because the grind will probably be too coarse.

    Ulca Pumps are designed to withstand their rated pressure, usually 15 bar and up to 18 bar depending on the model. This is their rated safe operating pressure. Trying to achieve acceptable espresso shots by using the PLV/OPV to limit the system pressure to a nominal 9 bar means that you are probably not achieving the ideal grind size for your particular machine. You are better off leaving the PLV/OPV set to where the manufacturer put it and spend the time determining the ideal grind setting to achieve an ideal shot.

    A Ristretto, by the way, is a shot of espresso that is pulled in the same manner as for a Single or a Double shot, but only half the volume of espresso is collected in the same time.... defined here:- http://tinyurl.com/a2k4w
    As a consequence of pulling a Ristretto in the preferred, correct manner, it is an inevitability that the System Pressure will rise above that achieved for a "normal" shot. I guess you can always call a "Short Shot" a Ristretto by pulling the shot glass away before a full 30ml or 60ml shot is achieved but this is not in reality, a Ristretto.

    Cheers,
    Mal.
    Hi Mal,

    This is the post that concerned me. You seem to be saying "leave the OPV at its factory preset". Whereas I believe the factory preset usually precludes using the machine for making a range of shots within accepted extraction parameters. (Although I think Isomac -for one- actually preset the OPV at around 10 bar, allowing for extraction at acceptable pressures for all shots.)

    It may be true that operating the OPV in this manner is not optimal and outside its design spec. However, this is not so with some units, especially some aftermarket units.

    In effect, what youre trying to do with the OPV is to decouple the pump pressure and flow rate over a range of flow rates. In this regime, the grind acts to determine the flow rate (shot time) and not the extraction pressure.

    Regards,

    Mark.


  36. #36
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    Re: Water on top of firm Silvia puck

    Hi Sparky,

    No, its not my intention to prevent experimentation by curious CSers who are seeking any and all tweaks to improve the quality of their shots. My main concern was to point out that not everyone should be playing around with a device that is essentially a Safety Mechanism.

    I know several people who absolutely love a great coffee but if they then went off and decided to adjust the PLV/OPV because of what they read or heard, I would be very nervous of the potential outcome of their endeavours.
    My brother for example, is a brilliant artist, part time philospher and musician, but to let him loose on the innards of an espresso machine would be a definite recipe for disaster. He doesnt have a technical bone in his whole body but let him loose with a paint-brush, piano or guitar and the outcome can be wonderful. Hes a mad keen motor cyclist too (like me) but ask him what pressures he runs in his tyres and hell come back with..."Pressures, what pressures? What do you mean by pressures in the tyres, how do I do that?" :-?

    I guess it just comes down ones personal experiences. I dont mind delving into the most complex electro/mechanical/hydraulic/aeronautical equipment because I understand the principles and theory behind the operation of most of this stuff. I also appreciate that not everyone is a tech-head like me and that I just shouldnt assume that anyone and everyone will understand the correct way of completing a technical task, no matter how apparently simple it may appear to me, you and other tech-heads. Safety devices should be treated with care and respect, and only adjusted by someone who understands what it is that they are actually doing. What if someone adjusts the valve in the wrong direction and increases the Safety Pressure setting to something beyond what is safe for their particular system. I know the Silvia can not be adjusted this way without substituting the original spring with a higher rated one, but plenty of PLV/OPVs are adjustable in both directions.

    For your purpose, you know Mark, a Pressure Control/Regulating Valve would be a more ideal device as the task you are expecting of the PLV/OPV is not its intended design/purpose or most efficient mode of operation. All the best,

    Mal.

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    Re: Water on top of firm Silvia puck

    Okay, Mal, I see exactly what youre on about. I would hope that anyone without technical savvy wouldnt even attempt to open their machine, but rather take it to a service technician. Its rather for those who will boldly go where no one has gone before that might benefit from attempting such an adjustment.

    Anyway, crisis averted. Back to code green.

    Cheers,

    Mark.

  38. #38
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    Re: Water on top of firm Silvia puck

    Quote Originally Posted by Sparky link=1125276405/30#36 date=1125975372
    Okay, Mal, I see exactly what youre on about. I would hope that anyone without technical savvy wouldnt even attempt to open their machine, but rather take it to a service technician. Its rather for those who will boldly go where no one has gone before that might benefit from attempting such an adjustment.

    Anyway, crisis averted. Back to code green.

    Cheers,

    Mark.
    Most definitely Mark,

    Onward and Upward..... ;D

    Mal.

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    Re: Water on top of firm Silvia puck

    Behmor Brazen - $249 - Free Freight
    I have some of my most lucid moments when mains voltage is coursing through me.

    Now which way does Frankies head go on...



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