ALTITUDE & SALINITY COMPENSATION:

If the sample contains salts or if you are performing the measurements at altitude different from sea level, the readout values must be corrected, taking into account the lower degree of oxygen solubility.  Altitude Compensation: all the readouts are referred to sea level, thus the displayed measurements are higher than the actual values. In fact, altitude affects D.O. concentration by decreasing its value.  The table on the left reports the oxygen solubility at various temperatures and altitudes, based on sea level barometric pressure of 760 mmHg.This gives an idea of the error that can be introduced at different altitudes and allows to calculate the quantity to be subtracted to correct the reading.

Salinity Compensation: the table below shows the influence of salt concentration in the measurement of oxygen.  In SM600 all the readouts are referred to 0 g/l of salinity value. In fact, salinity affects D.O. concentration by decreasing its value. The table below reports the oxygen solubility at various temperatures and salinity.  From the table it is possible to calculate the quantity to be subtracted to correct the reading.