Announcement

Collapse
No announcement yet.

Zahm and Nagel mis-reading

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Zahm and Nagel mis-reading

    Hey guys and gals,

    I've got a 100 bbl brite that I am in the process of carbonating, I have taken multiple readings on the beer and consistently am getting readings that are incorrect (I have been taking a sample after my reading for comparison). The Zahm is reading that the beer is at 3.21 volumes.....way high, after tasting I would guess the correct volumes are somewhere in the realm of 2.3. I'm getting to the point where I just don't trust the Zahm at all. I have taken it apart multiple times and calibrated both the temp and pressure gauge (per the Zahm webpage). Any help would be greatly appreciated.

    Chris
    Red Brick Brewing Co.
    Atlanta, GA
    Cellarman
    Chris Morgan, Cellarman
    Red Brick Brewing Co.
    Atlanta, GA

  • #2
    Have you lubed the piston? If that is sticky it might not slide out all the way and give you high readings.

    You probably already checked, but that piston should slide in and out like butter.

    Good luck- Mike

    Comment


    • #3
      I have already lubed the piston. Seems to slide like buttah!
      Chris Morgan, Cellarman
      Red Brick Brewing Co.
      Atlanta, GA

      Comment


      • #4
        Have you calibrated the pressure gauge? Have you cleaned the gauge recently?

        The Z&N gauges are adjustable, but they are not sealed. It's very common to get a little beer in the gauge, which will cause it to stick and read incorrectly. Remove the face of the gauge by turning it 1/4 turn CCW, soak in warm, soapy water for a bit, rinse thoroughly, blow dry while holding the needle with a fingertip, then add a small shot of light machine oil to the works. This is as per Z&N instructions.

        Now get a good test gauge and calibrate that puppy! The Z&N gauges are pretty reliable, but I often find them to be 1 or 2 psi off.

        Here's my calibration rig: http://discussions.probrewer.com/sho...alibration-Day! It cost ~$200 to build, but is worth its weight in gold!

        If your thermometer is a dial-type, it too needs calibration. Get a certified Mercury-In-Glass thermometer and check that thermometer. It's best to calibrate thermometers in the temperature range they'll be used. Don't just rely on boiling or freezing water--these points change with altitude, air pressure, and impurities in the water.

        I check the calibration on our Z&N Series 1000s on a monthly basis.

        While you're at it, lube the o-ring of the piston. Plumber's silicone grease is perfect for this. Now check for leaks by pressurizing the tester to 15 psi or so and immersing it in a bucket of water. I've replaced two of the valves on these recently.

        These tools are nearly bomb-proof, but do require some TLC and PM.
        Last edited by TGTimm; 01-23-2017, 02:18 PM.
        Timm Turrentine

        Brewerywright,
        Terminal Gravity Brewing,
        Enterprise. Oregon.

        Comment


        • #5
          It seems like you've already received a lot of great advice on calibration. So this may seem like a stupid suggestion but I'll say it anyway. Are you allowing adequate time between shutting off your carb stone and pulling a sample to allow the tank to equalize? I used to have false readings with 200bbl tanks if I wouldn't give the tank 10 mins to rest before pulling a sample.

          Comment


          • #6
            Broadway make a great point. I've made that mistake. Got a 2.6 vol reading but it was actually only 2.1.

            Sent from my SAMSUNG-SM-G890A using Tapatalk

            Comment


            • #7
              I have tried calibrating both pressure and temp gauges. For the pressure gauge I took a tank of CO2 and ran a line off of a regulator to a tri-clamp fitting, dialed the regulator in and opened the gas line, seemed to work well but as Timm said in his previous post, I don't know that I can trust that regulator.

              As for the temp calibration, we have a mercury lab thermometer that I used but I will try a broader range of temperatures today.

              Lastly, I've had the stone off all weekend, so I'm sure I'm not getting a false reading from that.

              I've taken apart the Zahm more times than I care to think about, it's a simple device so I'm thinking is has to be the gauges. I've also pressurized the Zahm and submerged it as will as let it sit out for 30 mins to see if there was a gasket leak, no leaks.

              Thanks again for everyone's input!

              Chris
              Cellarman
              Red Brick Brewing Co.
              Atlanta, Ga
              Chris Morgan, Cellarman
              Red Brick Brewing Co.
              Atlanta, GA

              Comment


              • #8
                Try calling Zahm, I had several issues and talked with them. I found them friendly and helpful
                Mike Eme
                Brewmaster

                Comment


                • #9
                  Originally posted by beerguy1 View Post
                  Try calling Zahm, I had several issues and talked with them. I found them friendly and helpful
                  ^^^ This. I have also had issues and they helped me out step by step to determine the source of the problem and fix it.

                  Comment


                  • #10
                    If you've taken the Zahm apart several times and are sure there are no leaks, it's down to calibration of the thermometer and pressure gauge. Your MIG lab thermometer should be good enough, but you really should get or build a reliable pressure gauge tester based on a professionally calibrated and certified pressure gauge.

                    All of your brewery gauges and meters should be calibrated on a regular basis. Temperature and pressure are the most important variables in fermentation, next to gravities.
                    Timm Turrentine

                    Brewerywright,
                    Terminal Gravity Brewing,
                    Enterprise. Oregon.

                    Comment


                    • #11
                      Can't reinforce enough TGT's point, above, about calibration/validation - not just pressure & temperature, but anything that is used to measure process and products.

                      Pressure and temperature control all dissolved gases levels so are particularly critical to brewing and quality control.

                      Just one question - as I understand you are seeing measured CO2 values that are higher than expected; do you nitrogenate at all? If so this will give errors on pressure-temperature CO2 measurements.

                      Comment


                      • #12
                        The ZN gauges do not last forever. I have had some last years and other not nearly that long. Just comes down to how it is treated. I have found debris can get lodged up in the tiny port on the gauge and cause inconsistent readings. We blow it out gently with compressed air every time we disassemble. Cheers.
                        Joel Halbleib
                        Partner / Zymurgist
                        Hive and Barrel Meadery
                        6302 Old La Grange Rd
                        Crestwood, KY
                        www.hiveandbarrel.com

                        Comment


                        • #13
                          Originally posted by BrewinLou View Post
                          The ZN gauges do not last forever.....
                          Agreed--But the ability to calibrate these gauges, combined with the ease of removing the face for cleaning, means the Z&N gauges have a longer usable life than most. We used Ashcroft fluid-filled pressure gauges for years, with calibration notes written in sharpie on the face--always confusing. There is no need for a fluid-filled gauge in the brewery--the fluid is to stabilize the needle against vibration and rapid fluctuation, neither of which is a problem on a fermenter or CO2 measuring device. I've been phasing the Ashcrofts out in favor of the Z&N gauges--which are about the same price.

                          The calibration rig I built includes a small regulator, so I can calibrate across a range of pressures. One of the most common failures of pressure gauges is a loss of linearity--they may calibrate at one pressure, but be far off at another. Another common problem is a sticking needle, which is easily diagnosed when running the pressure up/down.
                          Timm Turrentine

                          Brewerywright,
                          Terminal Gravity Brewing,
                          Enterprise. Oregon.

                          Comment

                          Working...
                          X