Rotronic EA35-SCS Calibration Standards Thermohygrometer Capsule. Calibration using traceable humidity standards is a simple process. Rotronic probes can easily be calibrated using a PC running HW4 software, or via the HP23-A handheld mentioned above. In most of our standards, we use unsaturated salt solutions supplied in packs of five sealed ampoules of the same humidity value. The only exception is in our 0.5 %rh standards, in which we use molecular sieve desiccant. Each ampoule is labelled with its %RH value and serial number. Included with the ampoules are five textile pads and a swiss calibration service (scs) calibration certificate for the batch for traceability and accuracy of the %RH standard.