idronaut Ocean Seven 304Plus Operator's Manual page 3

BATTERY REPLACEMENT/RECHARGING
 To gain access to the internal batteries, loosen the closing screws on the CTD top cover with a proper
screwdriver. Remove all water droplets around the top cover to prevent the penetration of moisture
inside the housing.
 Install two new 1.5V AA Alkaline cells in the double-battery holder or a new Lithium 3.6V cell in the
single-battery holder. INSTALLING TWO 3.6V LITHIUM BATTERIES IN THE DOUBLE-
BATTERY HOLDER AND CONNECTING IT TO THE OS304Plus TOP COVER WILL CAUSE A
PERMANENT DAMAGE TO THE OS304Plus CTD ELECTRONICS.
 If the CTD is not to be used for long periods (weeks or more),we strongly suggest removing the
internal battery from the CTD. This will eliminate the possibility of damaging the electronic circuitry
in case of battery leakage.
SELF-RECORDING USE
 The internal Real-Time Clock (RTC) keeper is powered by the CTD main battery. If the
battery is fully dead or disconnected, the RTC loses the date & time. It is mandatory to set
up the RTC or check that the RTC date & time are correct before starting a self-recording
data acquisition cycle.
 The CTD is equipped with a rotary magnetic power ON/OFF switch, present on the top
cover. The CTD is ON when the switching arm is rotated as indicated on the top cover
label. Once the self-recording configuration of the CTD has been set, the CTD can be
switched OFF and ON again at the sampling site, when it is ready for deployment.
VERY IMPORTANT: Allow a 30-second interval between each ON/OFF cycle.
LABORATORY USE
When the CTD is to be used in the laboratory to verify the measurement performance or to perform the CTD
sensor calibration, please interface the CTD from a portable computer (battery powered). In fact, using
desktop computers may generate ground loops and interferences that can affect the CTD sensor
measurements. In case a portable computer is not available, a USB port optical insulator must be placed
between the CTD USB cable and the PC USB port. A dedicated data acquisition program
"OceanSevenCalibration" is provided to properly acquire data from the installed sensors.
CONDUCTIVITY MEASUREMENT
 To obtain the best accuracy, the conductivity sensor and therefore the probe sensor head,
must be immersed in clean seawater for at least 15 minutes before measurements. For fresh
water application, the sensor does not require any hydration.
 When the conductivity sensor is not in use, it is kept dry. Therefore, when the conductivity
sensor is placed in water, very small bubbles may remain attached to the platinum ring
electrodes (seven). If such a thing happens, the measured value of conductivity will be
lower than the true one. To remove these air bubbles, degrease the inside of the
conductivity cell using cotton buds wetted with the Conductivity Sensor Cleaning Solution
or with liquid soap. Gently rotate the cotton bud against the whole internal surface of the
quartz cell. This will wet the platinum electrodes, thus reducing the surface tension of the
cell and considerably decreasing the risk of trapped air bubbles.
IDRONAUT – Brugherio (MB)
OCEAN SEVEN 304Plus CTD
IMPORTANT REMARKS
OCEAN SEVEN 304Plus CTD 12-2015