wirat
Well-Known Member
I bought a cheap Chinese TDS meter and was wondering the same thing. Nowhere does it say what scale it is calibrated to. I later discovered it is calibrated to the "Hanna" or "500" scale, because the calibration/buffer solution provided with it is 1382ppm, which is the calibration ppm for the 500 scale. I would think most Chinese knock-offs would be the same. If you got 1382ppm with it that would confirm.
Found this from a Hanna document:
"Hanna PPM Scales for Hanna Meters
1.Any meter that requires a calibration solution of
1500ppm is generally on the .7 calibration scale (called
the 442 scale)
2.Any meter that requires a calibration solution of
1382ppm is generally on the .5 calibration scale (
called the sodium chloride scale)..."
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