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On the occasion of the Oceanology International 2001 _ Miami _ April 3-5, 2001, Idronaut is proud to introduce the "Conductivity-Temperature Transfer Standard CT 01" which comes up to the line of the well proven, high performance oceanographic OCEAN SEVEN CTDs.
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Philosophy of the system
The working principle is the following: once the calibration of the reference thermometer has been well determined (Hart Scientific and Rosemount, the main suppliers of Primary Standard Thermometers guarantee an accuracy much better than 0.001 °C in the measuring range of 0 ¸ 30 °C), the conductivity quartz cell is filled with standard sea water (1 ampoule is sufficient to wash the cell at least 10 times, as its internal volume is very small, 20 ml only).
Then the cell is placed in a unique High Precision Titanium Bath, designed and made exclusively by HART SCIENTIFIC for this specific application, of which medium term stability is better than 0.001 (from 0 to 30 °C).
After reaching the thermal stability of the conductivity cell, the system acquires the conductivity calibration according to the declared value of the sea water reference ampoule.
This Transfer Standard System represents a different and probably superior approach respect to the use of even the most accurate salinometer. In fact, the conductivity reference cell used is a big, massive quartz cell in which 7 rings of platinum are fused inside the quartz slots. Black platinum coating (sponge) is not required; this allows the easy cleaning of the cell. Conversely, the best salinometer uses a small glass cell with only four platinum platinized electrodes, which require frequent calibration with standard seawater ampoules.
The "Conductivity-Temperature Transfer Standard" is a compact and rugged instrument designed for the metrology laboratories to perform calibration of oceanographic CTDs probes. It combines a Primary Standard 100 ohm SPRT (Standard Platinum Resistance Thermometer), a large size Idronaut self flushing cell provided with seven internal rings of fused platinum in the quartz with a microprocessor controlled high resolution and high accuracy electronic amplifier.
Optionally, the "Conductivity-Temperature Transfer Standard" can become a redundant measuring system when equipped with two temperature and two conductivity sensors.
The high performance electronics collects and transmits the temperature and conductivity readings through the RS232C interface from 1 to 10 times per second. The functions of the "Conductivity-Temperature Transfer Standard" are managed by means of a simple communication protocol with the RS232C interface.
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