The instructions for use for the Myron L ds meter are confusing. How often is this meter calibrated using the 3 solutions and when is the "S" value suitable as a check for calibration? I am curious to see how others are doing it.

We check the "S" (internal standard) daily before use. We calibrate with 15ppm, 150ppm, and 1500ppm solution weekly. Remember, the same wheel is used for the "S" and 1000 ppm range. So when you change the 1000 ppm range during your weekly cal., you also change the "S". Whatever the "S"S reads after the 1000 ppm cal. is the NEW "S". Place a sticker or something over the old standard and write the new "S" on it. Make sense?

that sounds like how we are doing it. The new S is written on tape and put on the side of the meter and the staff check to make sure that the meter is still going to the new "S". If not then the meter must be recalibrated with all 3 solutions. Is that how you do it Fred?

One tech was telling me that you check "S" and then turn the 1000 wheel til you get the "S" back on the value on the bottom of the meter. I have never heard of this and did not read this in the manufacturer's IFU. Do you know anything about that?