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  • Testing Silvias pressure without a gauge

    Theres a handy way to establish what the Silvia over-pressure valve is set at, without the use of a gauge.

    The ulka website http://www.ulka.it/eng/E.htm# says water flow at 9 bar should be 250 ml per minute.

    Place a blind filter into the portafilter, lift the water return hose from the tank so it will empty into a calibrated container.

    Turn on the brew switch and time, say, for 20 seconds, noting how much water is pumped into the container in that time.

    If it works out at 250 mls per minute -- the machine is doing fine, set for ideal extractions.

    Robusto




  • #2
    Re: Testing Silvias pressure without a gauge

    Is there a post covering how to adjust this on a Silvia should it need adjusting?
    Ive just got her, slightly second hand, about 18months old I was told, so might not have the adjustable valve that I saw something about in a post the other day.

    Thanks for any help

    Bullitt

    Comment


    • #3
      Re: Testing Silvias pressure without a gauge

      Gday Bullitt,
      adjusting the OPV on the Silvia is not as easy as the Gaggia as the OPV on the Silvia isnt adjusted by a screw.  If you want to mod the OPV, youll have to pull the OPV apart and add another washer/gasket to it.
      Have a look at this link, it gives you a step by step guide:

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

      Of course the standard disclaimers apply in relation to electricity, high pressure steam and hot water.
      Good luck,
      Steve.

      Comment


      • #4
        Re: Testing Silvias pressure without a gauge

        Thanks for that Ulka pump link, Robusto. Ive been wanting a way to work out Silvias pressure.

        Originally posted by robusto link=1143622054/0#0 date=1143622054
        Place a blind filter into the portafilter, lift the water return hose from the tank so it will empty into a calibrated container.
        Turn on the brew switch and time, say, for 20 seconds, noting how much water is pumped into the container in that time. If it works out at 250 mls per minute -- the machine is doing fine, set for ideal extractions.
        I just want to check something before I try this: Usually when I use a blind filter (to backflush) the water comes out the 3-way solenoid thinggy into the drip tray. Will removing the end of the water hose from the tank prevent this from happening? Why not just measure the amount of water coming out of the group?

        Also, do we know which model Ulka pump is in the Silvia (I know the power level of the pump in mine is 48w, but I understand some have a 50w pump)? If I get a flow rate of 300cc/minute it could mean 9 bar (if its the E4R) or 15 bar (if its the E5D).

        Cheers,

        Rob

        Comment


        • #5
          Re: Testing Silvias pressure without a gauge

          Robster, when backflushing, water comes out of the 3-way-valve into the drip tray only when you RELEASE the brew switch. The idea is to allow you pull a shot through the portafilter until youre done. When you release the switch, the valve opens and all the pent up pressure is diverted into the drip tray. Otherwise, removing the portafilter--still under pressure-- would create an explosive mess.

          The return hose is independent of the three-way valve. And water will flow through it irrespective of whether the end sits in or out of the tank.

          Why not measure flow through the group? You are testing pressure in the group. Pressure ordinarily created by the pump trying to overcome the packed coffee puck.

          The pump is the E5. Make sure you place your mouse pointer on the E5 part only on the left side of the web page, not the words "performance curve" just before E5.

          Hope this helps

          Robusto

          Comment


          • #6
            Re: Testing Silvias pressure without a gauge

            Thanks Robusto,

            My backflush technique has been to flick the brew switch on-and-off very quickly so I didnt realise the water exited the 3-way valve at the "off" position. Of course I should have worked it out: the other way around would mean waterd pour out of the 3-way valve instead of through the puck, with no coffee produced! Ever. Hulloo . . . what was I thinking?

            Ill give it a go in the coming days and report back.

            Cheers,

            Rob

            Comment


            • #7
              Re: Testing Silvias pressure without a gauge

              Originally posted by Lovey link=1143622054/0#2 date=1144380340
              Gday Bullitt,
              adjusting the OPV on the Silvia is not as easy as the Gaggia as the OPV on the Silvia isnt adjusted by a screw. If you want to mod the OPV, youll have to pull the OPV apart and add another washer/gasket to it.
              Have a look at this link, it gives you a step by step guide:

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

              Of course the standard disclaimers apply in relation to electricity, high pressure steam and hot water.
              Good luck,
              Steve.

              Thanks for the info and link.
              I havent got a blind filter yet, another item on the to do list
              Bullitt

              Comment


              • #8
                Re: Testing Silvias pressure without a gauge

                A blind filter is handiest, but not essential.

                Take some cloth or paper towling and wedge it tightly into the hole inside the bottom of the portafilter. Its got to block water under pressure, so make sure its fairly tight.

                Also make sure whatever you use can be readily extracted later! Put on any basket, and lock into the group.

                Instant blind filter "basket".

                Robusto

                Comment


                • #9
                  Re: Testing Silvias pressure without a gauge

                  Thanks Robusto, I will try something along those lines then.
                  I notice coffeeparts also have available a rubber? insert so I guess that is something that could be made at home as well?

                  Comment


                  • #10
                    Re: Testing Silvias pressure without a gauge

                    I purchased a portafilter with a pressure gauge (http://www.coffeeparts.com.au/accessories/pfgauge.html) and found my silvia has a pressure of 11-12 bar.  Interesting reading on coffee geek (http://www.coffeegeek.com/forums/esp...s/46475?Page=1) about peoples findings of optimal taste at specific bar temperatures.  It is unfortunate that the pressure on the silvia cannot be adjusted without taking the machine apart. I did find with a grind, distribution, tamp, and temperature surf that is spot on, some very good shots are still being produced.

                    While performing temperature surfing tests I found the temperature stability relatively good - about 1-2 degrees celcius during the shot up to 30 seconds.  After 30 seconds the temperature began to rise by a degree or two.

                    Does anyone else have any pressure stats on their silvia, done a pressure mod, found a sweet spot, or a link that covers this already?

                    Comment


                    • #11
                      Re: Testing Silvias pressure without a gauge

                      So I have a cheep sunbeam with an EP5 15bar pump and I wish to slow the flow rate down... Tamping, grinding and the special crema enhancer basket etc still have way too much flow rate and 10 - 12 sec shots are often teh norm, before teh crema turns blond :-)

                      What do I need to do to the Ulka pump :-) as thess system do not appear to have an OPV.

                      My assumption is that it is driven by frequency and thus if I was to change this I might have a better way to manage the flow / preasure.

                      In the process of drawing out the electronics as it only is 2 MC14017B ICs and a 2p4m Thyristor and a couple of resistors etc.

                      My first thought is that the Steam and Coffee switch drive the 2p4m diferently and thus I may be able to change a resistor or wire in a pot :-) Update: this cct is to regulate the Steam function where it pumps less frequently, in coffee mode it is a direct connection :-( So unless I toss in a diode and see what half wave rectification does I guess there is no easy fix.


                      Or is it a waste of time ?

                      Bring on the thoughts... Comments


                      Comment


                      • #12
                        Re: Testing Silvias pressure without a gauge

                        Gday AngerManagement,
                        the Ulka pump already has a diode inserted, giving it half wave rectification, check out Robustos link and go to the homepage of that site.
                        I think the biggest hurdle you might face with your current set up is the crema enhancing PF/basket, it throws the 30ml/30 second guideline right out. Try getting hold of a non pressurised PF and see how you go.
                        Hope this helps.

                        Comment


                        • #13
                          Re: Testing Silvias pressure without a gauge

                          Originally posted by Lovey link=1143622054/0#11 date=1145529151
                          Gday AngerManagement,
                          the Ulka pump already has a diode inserted, giving it half wave rectification, check out Robustos link and go to the homepage of that site.
                          I think the biggest hurdle you might face with your current set up is the crema enhancing PF/basket, it throws the 30ml/30 second guideline right out. Try getting hold of a non pressurised PF and see how you go.
                          Hope this helps.

                          Yea the 30ml is like in 10 sec Have no problem with getting a non pressurised PF but the timing is not much better and the result is so so.

                          Sorry to be so blind, but the link is about an OPV mod, unless you had another in mind.

                          And yes, after getting out my sons Magnifing glass and a quick check with the meter, a diode is in the pump. Not worth the effort to try any electronic mods on this system..

                          Will need to do some searching to see what others have done to manage the 30ml/30 second rule of thumb and good crema delevery ( and taste).

                          If you know of any links for Sunbeams and other like systems please pass them on.

                          AM

                          Comment


                          • #14
                            Re: Testing Silvias pressure without a gauge

                            Hi AM,

                            Try to get in touch with mattyj.... he used to own and use a Sunbeam before updating to his current Expobar and achieved a high degree of success by substituting the pressurised baskets with Krupps non-pressurised equivalents. From all accounts, he was able to produce pretty good coffee after this mod,

                            Cheers,
                            Mal.

                            Comment


                            • #15
                              Re: Testing Silvias pressure without a gauge

                              Originally posted by AngerManagement link=1143622054/0#12 date=1145536840

                              Yea the 30ml is like in 10 sec  Have no problem with getting a non pressurised PF but the timing is not much better and the result is so so.

                              Sorry to be so blind, but the link is about an OPV mod, unless you had another in mind.

                              And yes, after getting out my sons Magnifing glass and a quick check with the meter, a diode is in the pump.  Not worth the effort to try any electronic mods on this system..

                              Will need to do some searching to see what others have done to manage the  30ml/30 second  rule of thumb and good crema delevery ( and taste).

                              If you know of any links for Sunbeams and other like systems please pass them on.

                              AM
                              Gday AngerManagement,
                              if you decide to ditch the pressurised PF for a non-pressurised number, youll have to rely on the grind and tamp to determine your shot time, not a PF with funny inserts in it :P.

                              About the link, its in Robustos post at the top of the thread. Once in the web page, scroll to the bottom and click E models Homepage, no its not a link to a XXX site .
                              All the best.

                              Comment

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