Calibration Day!

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First Rate

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:

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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.

Excellent Timm....