Calibration; Pressure Sensor Calibration - idronaut Ocean Seven 304Plus Operator's Manual

SECTION THREE – COMMANDS
3.3.

CALIBRATION

This section provides general information on options available under the CALIBRATION MENU. In
details, it includes:
 Pressure sensor.
 Temperature sensor.
 Conductivity sensor.
Note
Calibration procedures of the optional sensors: Oxygen and Turbidity are described in the dedicated sections.
The below message shows the CALIBRATION MENU, as it is presented on the ITERM screen by the
CTD.
OCEAN SEVEN 304Plus - ID:304-0010101 {USR}[9.0_00-02/2012] 16:45:35.01 11-07-2012
Calibration
Idx – Sensor
255- Quit
001- Press
002- Temp
003- Cond
Idx:255 <
Exiting from the sensor calibration is done by confirming the default index code (255). When exiting,
the new calibrations are stored in the non volatile memory and the main menu appears on the screen.
WARNING

Modification of calibration affects both newly acquired data and stored data. Therefore, before
recalibrating a CTD sensor, we strongly suggest uploading data from the CTD memory.

IDRONAUT suggests a complete check and CTD sensor re-calibration once per year.

3.3.1. Pressure sensor calibration

To avoid that a minimum drift occurs in the pressure sensor, it is preferable to immerse the CTD in
water, up to about 10 cm from the CTD housing and wait a few seconds before starting the calibration.
After the pressure sensor is selected by means of the index code, the CTD displays:
Pressure is calculated by means of a polynomial interpolation against a calibration curve.
Press dbar
Where:
x
sensor offset
Pressure
Enter coeff.. x=a+bx+cx2
a = -18.173212
b = 0.018204
c = -12.46533E-12
The operator can confirm or modify the above coefficients. Typing an <ENTER> key confirms the
shown coefficients, while, typing new values followed by an <ENTER> key modifies the previous
coefficients.
IDRONAUT – Brugherio (MB)
= (a + bx + cx 2 ) – sensor offset
= pressure sensor reading in ADC counts
= automatically acquired at the end of calibration
OCEAN SEVEN 304Plus CTD
22
12-2015