Calibration

The metrology laboratory is equipped with usual references in oceanography and with bench dedicated to the calibration of the measuring instruments in the marine field.

Accredited for Temperature and Pressure quantities, the laboratory also considers quantities such as Conductivity/salinity, marine currents, dissolved oxygen, pH, pHT (total pH), turbidity, chlorophyll, speed of sound in water, …

TEMPERATURE

Calibration operations are performed according to different techniques (by comparison, fixed point) and using different devices (platinum resistance thermometers, resistance measurement bridge, water thermostated baths, …).

  • Range: -1.5°C to + 60.0°C.
  • Uncertainty:Uncertainty levels are dependent from employed techniques and devices in calibration. However, two main levels of uncertainty can be distinguished:     - Calibration between water triple point (0.01°C) and Gallium fusion point (29,7646°C) (fixed points from International Temperature Scale in 1990): U = 0.004°C     - Calibration by comparison with a reference probe in a thermostated bath from -1.5°C to +60.0 °C: U = 0.014°C according to the equipment used
  • Calibrated instruments: numerical thermometers, thermo-salinometers, CTD probes, velocimeters.

PRESSURE

Pressure calibrations are calibrations in relative pressure performed by comparison with a oil-operating pressure compensator.

  • Range: 2 measurement ranges

                      - From 100 kPa to 4 MPa.
                      - From 2 MPa to 80 MPa.

  • Uncertainty:

                    - From 100 kPa to 4 MPa:

                        U = (310  + 1.10-4P) Pa

                   - From 2 MPa to 80 MPa
                        U = (1200 + 1,3.10-4P) Pa

  • Calibrated instruments: pressure sensors, CTD probes, manometers, …

SALINITY

Calibrations are performed in a bath in comparison with reference sampling measured with a reference salinometer. The reference salinity is calculated from the conductivity ratio (measured with the reference salinometer), using the empirical formulas advocated by UNESCO “ The practical salinity scale, 1978”.

  • Range: from 2 to 35
  • Uncertainty: U= 0,01(k=2) in pratical salinity
  • Calibrated instruments: Salinometers

CONDUCTIVITY

Calibrations are performed in a bath in comparison with reference measurements. The salinity and the bath temperature measured by the reference equipment as well as the depth of the sensor allow to calculate the reference conductivity applying the iterative formula advocated by UNESCO in 1980 with C35, 15, 0 = 42,914 mS/cm.

  • Range: from 0 to 60mS/cm
  • Uncertainty: U= 0,01 mS/cm (k=2)
  • Calibrated instruments: Thermo-conductimeters

CELERITY

Calibrations are performed in a bath in comparison with reference measurements. The reference celerity is calculated from reference measurement in salinity and temperature from the bath and from the depth of the sensor using the equation advocated by UNESCO in 1983.

  • Range: from 2 to 35
  • Uncertainty: U= 0,01 (k=2) in pratical salinity
  • Calibrated instruments: Salinometers

DISSOLVED OXYGEN

Calibrations are performed in a bath (fresh or sea water) in comparison with reference sampling analysed based on Winkler reference method.

  • Range: from 0 to saturation
  • UncertaintyIncertitude sur la méthode de référence : from U= 4 µmol/l to 440µmol/l (from 0,13 mg/l to 14mg/l)
  • Calibrated instruments: Dissolved oxygen sensors, dissolved oxygen optodes.

pH / pHT

The calibrations are performed in pH or pHT according to the sensor’s technology and the expected type and quality of measurement data.

The calibration is performed by comparison with specific pH or pHT reference standards whose reference value is measured either with a pH meter with electrodes (pH), or with a spectrophotometer (pHT).

  • Range: pH = from 7 to 9 at 20°C
                      pHT = 8 at 25°C
  • Calibrated instruments: pH ou pHT sensors

TURBIDITY

The calibrations are performed by comparison with reference solutions obtained from a standard solution of formazin HACH (4000 NTU), by dilution.

  • Range: from 0 to 400NTU
  • Calibrated instruments: optical turbidimeters

FLUORESCENCE / CHLOROPHYLL A

The control of sensors is realised by comparison with reference solutions obtained from a standard  stock solution of fluorosceine (in powder).

The calibrations

  • Range: from 0 to 1000µg/l of fluoresceine
  • Calibrated instruments: optical fluorometer, chlorophyll sensor.

Get your equipment calibrated

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Some examples

Multiparameter probes

Field thermo-conductimeters

CCTD probes (Celerity Conductiviy Temperature Depth)