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  • Calibration Day!

    Just a reminder--never trust an untested gauge or thermometer!

    I'm calibrating twelve pressure gauges today--three brand new Zahm and Nagel adjustable gauges, and nine already in use. I've been replacing all our old Ashcroft pressure gauges with these Zahms, as they are they the only adjustable PGs I've found and the price is good. No more writing correction factors on the dial with a Sharpie!

    They require calibration fresh out of the box. All three were reading around 1-2 psi low.

    Now they're right:

    Click image for larger version

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    The black knob is a regulator, which allows me to check for linearity in the range we use. If I can't get the gauge calibrated at 10 and 15 psi, it goes back as faulty. All three passed.

    The STI digital gauge--0-50 psi--was purchased from Kodiak Controls--best price and excellent service. We had Kodiak calibrate it, and it gets sent back for calibration yearly. It's been back twice, and needed no adjustment.

    The range is important--most or all of these gauges you'll find online are 0-500 psi, and they are rated as precise to within 1% full range, so that's a big difference between an uncertainty of 1 psi and 10 psi. Be aware if you order one online--it will be the 0-500 range, regardless what you think you're buying. Kodiak was the only place I could find that had the right one, and their price was a fraction of what I paid for the three I returned as the wrong range.

    Thermometers get calibrated against a NIST-certified MIG thermometer, in an insulated bucket on a magnetic stirrer. All gauges and thermos need to be calibrated for the range in which they will be used, so mash-in thermos get calibrated at 175F, while fermentation thermos get calibrated at 75F.
    Last edited by TGTimm; 12-29-2016, 12:24 PM.
    Timm Turrentine

    Brewerywright,
    Terminal Gravity Brewing,
    Enterprise. Oregon.

  • #2
    Thank you for doing this properly.

    Too many brewers calibrate with ice water, or with another fucked up gauge, or with some other bullshit method.

    Comment


    • #3
      Zhamm also sells a pressure gauge tester.
      Brewmaster, Minocqua Brewing Company
      tbriggs@minocquabrewingcompany.com
      "Your results may vary"

      Comment


      • #4
        I think I undercut Zahm's price by at least a thousand bucks. And the gauge on the Zahm calibrator needs calibration on a regular basis, too. I guess you send it back to Zahm.
        Timm Turrentine

        Brewerywright,
        Terminal Gravity Brewing,
        Enterprise. Oregon.

        Comment


        • #5
          Originally posted by TGTimm View Post

          I'm calibrating twelve pressure gauges today--three brand new Zahm and Nagel adjustable gauges, and nine already in use. I've been replacing all our old Ashcroft pressure gauges with these Zahms, as they are they the only adjustable PGs I've found and the price is good. No more writing correction factors on the dial with a Sharpie!

          .
          Looks great! I'm building one myself. What have you used to plug the end of the "T" on the digital gauge? Is there any reason I should not just use a 90 degree elbow on the end there? I have gauges with 1/8" and 1/4" threads. Do you think I should put a "T" in for each thread size or just use a thread reducer when needed? Thanks!

          Comment


          • #6
            Andy--that isn't a plug, it's a bleeder valve to release pressure when I'm done--or have overshot my desired calibration pressure.

            I have an assortment of various fittings to go on the regulator so I can test anything I need to--1/8", 1/4", 1.5 TC flange, 2" flange, etc.
            Timm Turrentine

            Brewerywright,
            Terminal Gravity Brewing,
            Enterprise. Oregon.

            Comment


            • #7
              Works well for PRVs also! Thanks for the tip!
              Click image for larger version

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              Comment


              • #8
                Good looking rig.

                When I'm testing PRVs and spunding valves, I soak them down with soapy water or use a longer extension to mount them so I can immerse them in water. It's easier to see the bubbles than to hear the hiss.
                Timm Turrentine

                Brewerywright,
                Terminal Gravity Brewing,
                Enterprise. Oregon.

                Comment


                • #9
                  Timm,

                  What's the part number for the Z&H adjustable gauges? They have a few listed and I want to be sure to get the correct ones.

                  Cheers,
                  --
                  Don
                  Idyllwild Brewpub

                  Comment


                  • #10
                    Don: The ones I use are PN 1029.
                    Timm Turrentine

                    Brewerywright,
                    Terminal Gravity Brewing,
                    Enterprise. Oregon.

                    Comment


                    • #11
                      Originally posted by TGTimm View Post
                      Don: The ones I use are PN 1029.
                      Thanks, Timm! I'll have to get some of those!

                      Cheers,
                      --
                      Don
                      Idyllwild Brewpub

                      Comment


                      • #12
                        So, I'm one of those who uses the ice water bath method to calibrate my bimetal thermometers. I get pretty consistent results and it's cheap, but am interested in using an NIST-certified MIG thermometer. Do you have a preferred source for them? When I search for them, I mostly just get electronic thermometers. Thanks in advance.

                        Comment


                        • #13
                          The advantage to an MIG thermo is it stays calibrated. Electronic thermos need calibration.

                          I think I misstated above--our MIG calibration thermo is ASTM cert, not NIST. As far as I can determine, the difference is a traceable certification for the NIST--needed if using for food processing--and several hundred dollars of cost.

                          I don't recall where we got ours--it's been at least 5 years (and the brewers haven't broken it yet). The ASTM cert. MIG thermos come in different ranges--ours is 30-180F, which is ideal for calibrating all our brewery thermos. All it says on the thermo is ASTM cert, Made in Germany.
                          Timm Turrentine

                          Brewerywright,
                          Terminal Gravity Brewing,
                          Enterprise. Oregon.

                          Comment


                          • #14
                            Originally posted by AndyHannas View Post
                            Works well for PRVs also! Thanks for the tip!
                            [ATTACH]58434[/ATTACH]

                            Can we come up with a parts list and maybe a how to video?

                            Here is a start to the list. Please make corrections or add additional items as needed.

                            And if you feel like making a short video of the calibration process and posting it that would be great, TGTimm or AndyHannas "Wink.. Wink.."

                            Working from left to right
                            Parts list
                            • 1/4'' NPT Male to TC Clamp? No idea where to find this one

                            Comment


                            • #15
                              As you can see in my set-up, I left out one of the Ts in the set-up above, and simply used the gauge port of the regulator for the gauge I'm calibrating. No need for a third gauge, which isn't likely calibrated, anyway.

                              You want to be sure to use a regulator that is for the range you're testing. For my purposes, this would be 0-30 psi.

                              You'll also need a collection of various bushings and bells to accommodate different gauge stem sizes, and possibly a 2" TC to NPT adapter for larger PRVs and spunding valves.

                              The digital gauge will need to be returned to Kodiak for calibration every year. Cost was $80 last year.
                              Timm Turrentine

                              Brewerywright,
                              Terminal Gravity Brewing,
                              Enterprise. Oregon.

                              Comment

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