Hach 2659405 StablCal® Turbidity Standards Calibration Kit, 2100P Portable Turbidimeter, Sealed Vials

Nice, linear calibration. DMRQA sample results were right on target. No complaints.

These are great standards. I use them for the Hach 2100P, so the photo is wrong, as the 2100P uses the shorter vials, so as long as you use the part number 2659405, you should get the correct sized vials. Hach packages them in mini pelican-like cases with foam, so great if you carry them on their own, but annoying if you use the turbidimeter in the original case, since they do not easily fit in there (I cut down the foam that they came in, so it would fit in the case and hold them tightly). The set I got in November 2019 are shown as not expiring until January 2021, so that is good. The previous set that I bought expired in April 2018, but were still good until probably July 2019 or so, when I noticed that the <0.1 was consistently reading high during calibration and checks. This is annoying as you cannot usually find the individual standards to replace bad ones, and I don't want to mess with mixing my own. Previous purchases of these standards, though, tended to last 2-3 years or more, so I am not sure if I got lucky on earlier lots, or if they are not as robust as they used to be. Prices have also gone up - when I bought the last set in 2017, the average price was around $150, and now is around $200 (from Thomas Scientific were $190).