Hanna Instruments solution for a known magnesium hardness standard for verifying a Checker HC, one model.
HI719-11
This Hanna Instruments calibration solution measures a known magnesium hardness standard for verifying a Checker HC.
A colorimeter that has drifted still returns confident numbers, and nothing in the reading says it is wrong. Running a known standard is the only way to find out, and it is the evidence an auditor asks for.
A standard is only a standard while it is uncontaminated and in date. Pour what you need into a clean beaker, never dip an electrode into the bottle, and never return what you poured. Cap the bottle immediately — several of these solutions change value simply by standing open.
Write the opening date on the label. An expired or contaminated standard does not announce itself; it quietly calibrates every instrument in the laboratory to the wrong value.
Check against the standard before a run of samples, not after; a failed check afterwards puts every result of that run in doubt.
Supplied as one model.