The Temperature Sensor; The Conductivity Sensor Equipped With The "Idronaut Seven-Ring Cell - idronaut Ocean Seven 304Plus Operator's Manual

SECTION ONE – SYSTEM DESCRIPTION

1.14.2. The temperature sensor

The temperature sensor is a platinum resistance thermometer (type Pt 100 ohms at 0°
C), fitted on a thin stainless steel housing, able to withstand up to 700 bar. The
sensor has a very low response time (50 ms) and a high stability of reading with
ageing. The drift of reading (sensor plus associated electronics) is less than 0.0003°
C per year.
Type:
Measurement range:
Accuracy:
Resolution:
Response time:
Maximum pressure:
Sensor body:
Life:
Calibration frequency:
Compensation:
Maintenance:

1.14.3. The conductivity sensor equipped with the "IDRONAUT seven-ring cell"

The conductivity sensor is a unique flow-through self-flushed cell with seven
platinum ring electrodes. The central ring is excited with alternate current
flowing to both the outermost rings. The two adjacent pairs of rings sense the
relative drop in voltage due to the electrical conductivity of the measured
water. The outermost pair of rings is grounded to shield the measuring cell
from any outside electrical interference.
cylindrical plastic body, which guarantees thermic insulation and is filled with
silicone oil and provided with a rubber bellow to achieve pressure
compensation. The IDRONAUT conductivity sensor and its associated
electronics are designed to work both with plain and black platinised platinum
electrodes. These electrodes have the advantage that they can be used in both
clean and dirty water without the fear of contamination. Should electrode
contamination occur, they can be easily cleaned (even with up to 30%
hydrochloric acid) without affecting the CTD performance or requiring recalibration. Because of its
big internal diameter and short length, the cell does not need a pump, as it is easily flushed during
profiles. The other conductivity flow cell sensors available on the market do not have the technology
of the "IDRONAUT seven-ring cell".
The small, closely spaced temperature and conductivity free-flow sensors eliminate the need for
adding pumping. Time constant of the conductivity sensor is 50 ms, at 1 meter per second water flow.
Measurement cell:
Measurement range:
Accuracy:
Resolution:
Response time:
Max pressure:
Sensor body:
Compensation:
Life:
Calibration frequency:
Maintenance:
IDRONAUT – Brugherio (MB)
Pt100@0°C.
-5..+35 °C.
0.003 °C.
0.0006 °C.
50 ms @1 m/s.
700 bar.
AISI 316L.
unlimited.
yearly.
none.
none.
The cell is mounted in a special
7 platinum rings deposited inside a quartz tube. Internal diameter
8mm, length 45 mm.
0..90 mS/cm.
0.009 mS/cm.
0.001 mS/cm.
50 ms @1 m/s.
700 bar.
black plastic and titanium.
automatic compensation of the pressure and thermal effect on
the cell geometry are performed by the acquisition software.
unlimited.
yearly.
cleaning using the IDRONAUT "Conductivity sensor cleaning
solution".
OCEAN SEVEN 304Plus CTD
10
12-2015