Before starting the verification procedures, make sure that you have a sample holder at hand. Check the condition of your standard refractive index liquids. You need a cleaning solution (ethanol or IPA) and tissues to clean the sensor prism and the sample holder between the samples.
The sample holder keeps the sample on the prism surface and also keeps the ambient light out. The universal sample holder PR‑1012 can be used with any PR‑23 sensor (in PR‑23‑M only the top part of the sample holder is needed).
The verification of the PR‑23 sensor calibration is made using a set of standard refractive index liquids with the nominal values at +25 °C (+77 °F):
The accuracy of the certified standard refractive index liquids is ±0.0002 and they can be traced back to national standards: N.I.S.T Standards # 1823 and # 1823 II.
The repeatability of PR‑23 sensor, that is the deviation from the latest nD calibration, is within ±0.0002.
As the specified accuracy of PR‑23 is ±0.0002, the representative level is the sum of the 3 accuracy specifications, ±0.0004.
Vaisala provides a set of standard R.I. liquids, PR‑2300, containing these 5 liquids. You can order the set directly from Vaisala or your nearest representative.