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OSIL provides support, servicing, calibrations and repairs for hydrographic instruments from its well-equipped facilities in the UK.

OSIL offer a range of in-house calibrations and services for:

CTD’s
Temperature Sensors
Turbidity Sensors
Sound Velocity Sensors
Current Meters & Tide Gauges
Multiparameter Sondes
AML X Change Sensors
Guildline Salinometers
Pre & Post Cruise Calibration Checks

Calibration intervals are usually recommended at 12 months to ensure sensor accuracy (18 months for SV Xchange sensors).

Conductivity (C)

Conductivity readings can be affected by mineral build up on the electrodes, biofouling or damage to the glass cell.Conductivity sensors are usually calibrated by OSIL with 9 points, and a minimum of 5 points, in variable temperature circulated salt water calibration baths and all points are checked using one of our in-house Guildline salinometers.

Temperature (T)

Temperature sensors are usually calibrated by OSIL at 9 points, and a minimum of 5 points, often alongside the conductivity calibrations, using variable temperature circulated salt water calibration baths.

Pressure / Depth (D)

Non-temperature compensated calibrations are undertaken at room temperature using a dead weight tester. Multiple pressure points are taken spanning the full scale range of the pressure sensor. The raw data from the pressure sensor measurement is then curve fit to the actual pressure applied by the dead weight tester.

Sound Velocity (SV)

Accurate sound velocity measurements are critical for sonar and multibeam systems to correct density differences through the water column. Calibration is undertaken in fresh water for greater accuracy (0.02 m/s instead of 0.25 m/s in salt water), and in precisely controlled homogenous conditions using a circulated calibration tank with heat flow controls. Total dissolved solids must be less than 10 ppm, and the temperature must be stable and measured to within 0.0002° C (using a Platinum Resistance Thermometer).

Pre & Post Cruise Calibration Checks

OSIL offer a CalCheck service, which is available for a wide range of instruments. The CalCheck is an intermittent calibration verification that can be undertaken pre and/or post-survey to ensure that there is no drift in readings over the deployed period, and is often required by end clients.

Turbidity and other parameters

OSIL stock a wide range of solutions for accurate calibration of a number of other parameters.

All calibrations include full reports and are fully traceable using our quality system.

OSIL operates an ISO9001-2015 accredited facility.

Temperature Standards/Transfer Standards:


  • Isotech Melt Point of Gallium
  • Triple Point of Water
  • Tinsley SPRT
  • Isotech Bridge

Conductivity/Salinity Standards:


  • Guildline Autosal and Portasal
  • IAPSO Standard Seawater
  • OSIL are ideally placed regarding calibration standards for conductivity and salinity, as OSIL operates the IAPSO Standard Seawater service from within its facilities, and are global representatives for Guildline salinometers.

Pressure Standards:


  • DH Budenberg Dead Weight Tester
  • (calibrated to UKAS standards)

Guildline 5010 Specifications


  • Range -9.9°C to 65 °C
  • Stability ± 0.002 °C

Guildline 8400B Specifications


  • Range 2 to 42
  • Accuracy ± 0.002

DH Budenburg DWT Specifications


  • Range 100 to 10,000 PSI
  • Accuracy Better than 0.01% of reading

Isotech F700 Bridge Specifications


  • Accuracy < ± 0.5ppm
  • Resolution 0.25ppm

Tinsley 5187SA SPRT Specifications


  • Range -189 °C to 660 °C
  • Accuracy ± 0.001°C

Commonly Supported Manufacturers:


  • Aanderaa
  • Seabird
  • Idronaut
  • AML
  • RBR
  • Wetlabs
  • SAIV
  • Hydrolab
  • Guildline

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