Calibration

Each miniDOT is calibrated separately in PME's calibration chamber before being shipped to the customer. We calibrate at 12 oxygen concentrations each at 8 temperatures for a total of 96 calibration points.  However we do not as yet use the sodium sulfite zero point in our calibration procedure.  When miniDOT displays an oxygen measurement less than about 1 mg/l it is computing the value based upon an extrapolation of higher concentration oxygen measurement.  These calibration extrapolations are subject to more error than the interpolations used at higher concentrations.  miniDOTs read a slight negative value when exposed to zero oxygen.  We account for this by specifying a overall absolute error as well as a fractional error for miniDOT performance.

Please send calibration questions to info@pme.com.