Nova-Tech DO 700 - Manual (Page 11)

5
4. CALIBRATION
The DO 700 has three measurement modes; DO as % saturation, DO
as mg/L (or ppm) concentration, and temperature.
Dissolved oxygen levels vary with temperature, barometric pressure,
and salinity, so calibration must be performed with consideration of
these factors. It is necessary to set the proper temperature,
barometric pressure and salinity values prior to performing any
DO calibration or measurement.
See Section 4.1 — Temperature Calibration .
See Section 5.6 — Barometric Pressure Adjustment .
See Section 5.7 — Salinity Adjustment .
The DO 700 will accept two % saturation calibration points; 100%
using saturated air or air-saturated water, and 0% using zero oxygen
solution. When 100% or 0% calibration is performed, the concentration
value is adjusted accordingly. Therefore, it is not necessary to calibrate
the concentration mode. If calibrating for 0% oxygen, note that the
meter will take several minutes to reach 0% saturation value and
constant stirring is not required.
The following table lists calibration values in % saturation calibration
mode with two different barometric pressures. Note that the saturation
value (92.1%) has decreased due to the lower barometric pressure
entered.
% Saturation
(of factory default value)
Calibration Value
(760mmHg)
Calibration Value
(700mmHg)
less than 10% 0% 0%
10.1% to 49.9% CAL ERR CAL ERR
50% to 150% 100% 92.1%
If calibration is attempted from 10.1% to 49.9%, CAL Err message is
shown—calibration is rejected and the display will return to calibration
mode.