XR 420/620 Fresh Water CTD

XR-420CTDf (freshwater) is small, autonomous data logger designed to monitor conductivity, temperature and pressure. Specific conductivity, salinity, depth and speed of sound can be derived through post-processing.

Uses 3-electrode conductivity sensor for range 0 to 2 mS/cm with resolution of less than 0.02 micronS/cm, temperature sensor standard or fast time constant (3 seconds or <100 milliseconds for external types) and pressure sensor accuracy is 0.05% of the full scale and achievable resolution is 0.0001%.

The XR-620CTDf is the profiling version of the standard XR-420CTD logger; it includes all of the above features, plus 6Hz maximum sampling rate, fast thermistor (0.095s time constant), thresholding capability (logger only samples while submerged) and optionally, a fast response dissolved oxygen sensor, approximately 1 sec for 63% at 25ºC.

• XR- 420CTD and XR-620CTD fresh are available in two casings, Delrin (up to 740 m) and titanium (up to 2000 m)
• All calibration constants are stored in the logger
• 8 MB Flash memory standard (2.4M samples), up to 8 GByte option
• Battery is 1.3Ah internal with external battery options or power supplied over the cable from the deck
• RS232 or RS485 serial communication allows real-time operation over long cable links
• Additional sensors can also be fitted