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Measuring Group Head Pressure on a HX machine

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  • Measuring Group Head Pressure on a HX machine

    Hi All,

    I recently upgraded to the beasty Rancilio S24, which is just a joy to run.

    Quick question though, would anyone know how to measure the group head pressure (as opposed to the boiler pressure, which doesnt seem to move from the 1.3-1.5 bar mark while in use)? I was thinking of setting the OPV to 9 bar at the group, but don't have any fancy brew pressure PF to do so. Is there any other way to set it up like that??

    Cheers,
    Aaron

  • #2
    I can lend you a portafilter+gauge if you can pickup/dropoff in the city, but I dont have a valve to regulate the allowed flow, so you just loosen up the fittings until 60ml drips out over 30 seconds. Send me a PM

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    • #3
      But without a gauge, take the return hose out of the tank (The hose with nothing on the end), and measure the outflow with a blind basket.

      The EP5 pump graph is below, 100% of the flow will be going through the return hose, so check how many ml/min comes out and find the range it falls in on the graph, dotted lines represent the tolerance/variation that is possible, so if you measured 260ml/min like in the graph, it could be anywhere between 7 and 10 bar. This does not take into account any pressure losses happening between the OPV and the group, for that you need a portafilter gauge with appropriate flow.



      And take it easy on the pump, the specs say it can run for 2 minutes on with 1 minute breaks.

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      • #4
        Pm'd you Jimmy.

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        • #5
          Measuring the Bypass Volume is really nothing better than an indicator, you know. Pretty rough...

          You'd have to allow an error margin of +/- 1.25Bar for a nominal bypass volume. Still far better to use a decent pressure gauge/needle valve setup (or similar). I'd take up the offer above or contact Greg Pullman to use his rental hardware.

          Mal.

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          • #6
            Thanks Mal. Advice has been taken.

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            • #7
              Would you believe the only piece I needed to put this monstrosity together from parts I had already was a 1/4" nipple?



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              • #8
                Arrrghhh ! ..Frankengauge gage !

                Are you sure you couldnt fit a temp probe in there somewhere ?

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                • #9
                  I think with pressure taken care of temperature can be tuned reasonably easily by taste... i.e. I dont have a temp probe

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                  • #10
                    Why do you have a valve on there? Any reason or just needed those fittings to complete the job?

                    I'll take a photo of mine which I made a few days ago.

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                    • #11
                      I just went over to Reece plumbing supplies and brought my group handle and gauge. $4.70 later I had a fairly handy tool
                      Attached Files

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                      • #12
                        Originally posted by brendogs View Post
                        Why do you have a valve on there? Any reason or just needed those fittings to complete the job?

                        I'll take a photo of mine which I made a few days ago.
                        There will be a small difference between the pressure measured with flow and without flow, restrictions/bends in the path between the opv/bypass and the group will cause pressure drops only when theres flow past them

                        Nice work, but you got the same gauge at reece for under $4.7? evilbay got me again

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                        • #13
                          Nah I got the gauge off evilbay also.

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