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  • Brew pressure measurement on the cheap

    Hi,

    My machine only has a boiler pressure gauge, not brew pressure. I replaced the pump some time ago, and just dialled in the pressure based on the quality of the shot; not the best approach, but one that seemed work O.K. for the time being.

    Today I went down to my local trade supplier, and bought a few fittings to go on the base of my filter holder. I already had the gauge down in the garage....its good to finally put it to use.

    Total outlay was around $8, so the skinflint in me was happy. Ill give it a try later today.

    Regards,
    Phil

  • #2
    Re: Brew pressure measurement on the cheap

    VERY BIZZARE

    I cannot upload a photo from here (I broke my mobile phone yesterday... Doh!) but I have the same looking thing on my desk at the moment for the Boema!

    In fact it looks like the very same group handle (and a Boema switch panel in the background!).

    Mine uses a blind filter with a hole in it (I dont think you want the basket to restrict the pressure).

    Gauge is a 0-250 PSI (0-1600 kPa).

    (Insert Twilightzone music here)

    Comment


    • #3
      Re: Brew pressure measurement on the cheap


      You cant use a filter basket in the PF unless you have a seal under the lip of the basket that will hold the pressure. I used a similar arrangement without a basket, as the lip of the PF alone was good enoug to seal. Some PF have notches in the lip that prevent you doing it this way, though.

      Cheers,

      Mark.


      Comment


      • #4
        Re: Brew pressure measurement on the cheap

        Hi Andy,

        Yep, thats a Bo-Ema youre lookin at! Id read your resto. thread some time ago....I did a similar thing, but tarted up the scuffed stainless a bit and have never looked back.

        I just tried it, and for some reason the group seal is leaking when using the double filter basket. I only have one blind filter, so will avoid drilling it for now. The blind and the double appear to have the same lip profile, so Im not sure why its happening.

        Id have thought that once the pressure equalised on either side of the filter basket, it should work O.K.

        Regards,
        Phil



        Comment


        • #5
          Re: Brew pressure measurement on the cheap

          Originally posted by Sparky link=1175222260/0#2 date=1175224214
          You cant use a filter basket in the PF unless you have a seal under the lip of the basket that will hold the pressure. I used a similar arrangement without a basket, as the lip of the PF alone was good enoug to seal. Some PF have notches in the lip that prevent you doing it this way, though.

          Cheers,

          Mark.

          Doh! Of course! The PF actually has a hole drilled up near the lip, which would prevent this ever working until its plugged. I also am not sure that the seal would be good enough without a filter.

          Hmm, many a slip twixt cup and lip....

          Comment


          • #6
            Re: Brew pressure measurement on the cheap


            Filter baskets are not designed to have high pressure on both sides of them. So I doubt that youll get a good seal using a basket. I managed to get a good seal using just the PF lip, but my PF didnt have a hole in it.

            You could use silicone gasket compound to seal it all up. It can handle the heat and the pressure fine, and is non-toxic to boot. Youll have to wait for 24 hours for it to cure though.

            Cheers,

            Mark.

            Comment


            • #7
              Re: Brew pressure measurement on the cheap

              Yeah Mark, I wasnt thinking it through at all; its obvious in hindsight though!

              I just went and brazed up the hole; I dont see a safety issue here. I then made an O-ring that fits between the PF and filter. Up, up and away! Ill tidy it all up and make it permanent down the track.

              Brew pressure is a little low, an indicated 850 kPa or 8.5 bar. Nice to know, and this arvos project will be to re-adjust. The lawns can wait!

              Regards,
              Phil

              Comment


              • #8
                Re: Brew pressure measurement on the cheap


                8.5 bar sounds sweet.

                Im currently at 9 bar and looking to reduce to 8.5 bar.

                Anyway, its good to be able to tweak things and try new things out.

                Comment


                • #9
                  Re: Brew pressure measurement on the cheap

                  Howdy All,

                  Just made mine this morning & tested my BZ35e.
                  Im getting a good seal just using the PF lip.
                  Ive just made some adjustments to the procon pump & now Im getting 9 bar.

                  Karl

                  Comment


                  • #10
                    Re: Brew pressure measurement on the cheap

                    Hi Karl,

                    More convergent thinking! I was toying with the idea of a 45° fitting; maybe in MkII.

                    I may get away without a filter if I replace the group seal (its now over a year old). Maybe thats a good field test of the seal....?

                    Regards,
                    Phil

                    Comment


                    • #11
                      Re: Brew pressure measurement on the cheap

                      So guys, please explain the process of checking the pressure with these things.

                      Do you just hit the brew switch like you would when using a blind filter to backflush and switch off when the pressure looks/sounds to have peaked?

                      And Coffee Parts for a guage?

                      Comment


                      • #12
                        Re: Brew pressure measurement on the cheap

                        Hey Phil,

                        Yeah the 45° fitting certainly makes it very easy to read the gauge.

                        Regards,
                        Karl

                        Comment


                        • #13
                          Re: Brew pressure measurement on the cheap

                          Originally posted by Thundergod link=1175222260/0#10 date=1175232927
                          So guys, please explain the process of checking the pressure with these things.

                          Do you just hit the brew switch like you would when using a blind filter to backflush and switch off when the pressure looks/sounds to have peaked?

                          And Coffee Parts for a guage?
                          Thats pretty much what Ive been doing today; Ive purged air ala backflush, which has essentially made no difference, and turning off after a stable pressure has been determined. Adjustment of course depends on your machine.

                          Coffee Parts make available a complete PF based device where the gauge is plumbed in to the end of the handle, which is a convenient option. They also have separate gauges that could be used for DIYing. The same sort of place that sell the raw brass fittings will also have gauges, most likely in psi and/or kPa, which is an easy conversion.

                          Regards,
                          Phil

                          Comment


                          • #14
                            Re: Brew pressure measurement on the cheap

                            Its a good gizmo to see exactly where you are at with the pressure at the group head.  

                            I found a camera and have taken a couple of pics...





                            You can see its a slightly different take on the same solution.  The gauge fittings have been terminated on top of the blind filter so the whole thing seals without leaking around the basket.

                            The good thing about using a Boema group handle with the smaller side lugs is that it fits the ECM Giotto as well as the Boema and maybe some other machines too (where the inverse is not true).

                            On the Giotto it was interesting to see their patented pre-infusion on the needle.  Zero pressure measured for about 1.5-2 seconds and then a slow ramp-up to full pressure in 5 or so seconds.  

                            ...sort of reverse engineering of an espresso machine when you know what is really happening.

                            ;-)



                            Comment


                            • #15
                              Re: Brew pressure measurement on the cheap

                              Not sure exactly what you brazed and what you didnt Andy, but one way to achieve this without sacrificing a portafilter or having to worry about pressure on both sides of the basket would be to braze / seal the brass fittings to the blind filter with a threaded outlet tube thinner than the hole in the bottom of the PF. Then you can just insert the blind filter with fittings attached into the PF which will have the outlet tube poking out the bottom, and screw the gauge on from the outside. Doesnt require any mods to the portafilter and the pressure stays within the blind filter and its tubing rather than the base of the PF.

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