Optional with calibration
Jeroen Smits
Manager Product- en Sector Specialists
Data acquisition
HOBO MX802 Water Data Logger
The HOBO MX800 series of wireless data loggers offer a versatile and customizable solution for…
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HOBO W-CTD-xx CTD Sensor
CTD Sensor for HOBO MX800 Series Water Loggers
The CTD sensor is an interchangeable sensor that seamlessly integrates with HOBO MX800 Series Water Loggers to measure conductivity, temperature, and water level. When attached to a HOBO MX800 Series Water Logger, this sensor also enables the logger to calculate specific conductance, salinity, and total dissolved solids (TDS).
The CTD sensor can be directly attached to the fully submersible MX801 model or connected via cable to the direct-read MX802 model. With the MX802, there’s no need to remove the sensor from the water to download data, simplifying the process significantly.
Key Features
- 4-Electrode Conductivity Sensor: Provides a wide measurement range, ideal for monitoring both freshwater and saltwater environments.
- Centrally Located Conductivity Sensor: Minimizes the effects of stilling wells or protective guards, ensuring accurate measurements.
- Durable Ceramic Water Level Sensor: Positioned at the sensor tip for precise measurement of shallow water levels.
- Direct Water Level Readings with the MX802: No post-processing required, saving time and effort.
- Compact Design: With a diameter of just 1 inch, the sensor is suitable for use in narrow wells, with the cable connected to the MX802 positioned above the well.
- Fast Response Temperature Sensor: Positioned near the sensor tip, the temperature sensor reacts quickly to changes in water temperature.
- Specially Treated Stainless Steel: Designed to withstand saltwater conditions, ensuring long-lasting durability of the sensor.
This CTD sensor offers the flexibility and accuracy you need for reliable measurements in various water environments. Whether working in freshwater or saltwater, the HOBO CTD sensor delivers consistent performance and simplifies the collection of essential data.
Technical specifications
Conductivity Measurements
Measurement Range
Electrical conductivity and specific conductance: 0 to 100,000 µS/cm
Salinity using PSS-78: 2 to 42 PSU
Total Dissolved Solids (TDS): 0 to 100,000 mg/L
Calibrated Range
Electrical conductivity: 50 to 80,000 µS/cm
5° to 35°C
41° to 95°F
Accuracy
Conductivity: +/-2% or 15 µS/cm whichever is greater
Salinity: +/-2% of reading or 0.1 PSU, whichever is greater
Resolution
Conductivity:
0.1 µS/cm from 0 to 1,000 µS/cm
1 µS/cm from 1,000 to 10,000 µS/cm
10 µS/cm from 10,000 to 100,000 µS/cm
TDS: 0.1 mg/L
Salinity: 0.01 PSU
Response Time
1 second to 90% at a stable temperature
Absolute Pressure and Water Level Measurements W-CTD-01
Range
0 to 207 kPa (0 to 30 psia); approximately 0 to 9 m (0 to 30 ft) of water depth at sea level, or 0 to 12 m (0 to 40 ft) of water at 3,000 m (10,000 ft) of altitude
Factory Calibrated Range
69 to 207 kPa (10 to 30 psia), 0° to 40°C (32° to 104°F)
Burst Pressure
310 kPa (45 psia) or 18 m (60 ft) depth
Water Level Accuracy*
Typical error: ±0.05% FS, 0.5 cm (0.015 ft) water
Maximum error: ±0.1% FS, 1.0 cm (0.03 ft) water
Raw Pressure Accuracy**
±0.3% FS, 0.62 kPa (0.09 psi) maximum error
Resolution
<0.02 kPa (0.003 psi), 0.21 cm (0.007 ft) water
Pressure Response Time***
<1 second to 90% at a stable temperature
Absolute Pressure and Water Level Measurements W-CTD-02
Range
0 to 400 kPa (0 to 58 psia); approximately 0 to 30.6 m (0 to 100 ft) of water depth at sea level, or 0 to 33.6 m (0 to 111 ft) of water at 3,000 m (10,000 ft) of altitude
Factory Calibrated Range
69 to 400 kPa (10 to 58 psia), 0° to 40°C (32° to 104°F)
Burst Pressure
500 kPa (72.5 psia) or 40.8 m (134 ft) depth
Water Level Accuracy*
Typical error: ±0.05% FS, 1.5 cm (0.05 ft) water
Maximum error: ±0.1% FS, 3.0 cm (0.1 ft) water
Raw Pressure Accuracy**
±0.3% FS, 1.20 kPa (0.17 psi) maximum error
Resolution
<0.04 kPa (0.006 psi), 0.41 cm (0.013 ft) water
Pressure Response Time***
<1 second to 90% at a stable temperature
Absolute Pressure and Water Level Measurements W-CTD-03
Range
0 to 850 kPa (0 to 123.3 psia); approximately 0 to 76.5 m (0 to 251 ft) of water depth at sea level, or 0 to 79.5 m (0 to 262 ft) of water at 3,000 m (10,000 ft) of altitude
Factory Calibrated Range
69 to 850 kPa (10 to 123.3 psia), 0° to 40°C (32° to 104°F)
Burst Pressure
1,200 kPa (174 psia) or 112 m (368 ft) depth
Water Level Accuracy*
Typical error: ±0.05% FS, 3.8 cm (0.125 ft) water
Maximum error: ±0.1% FS, 7.6 cm (0.25 ft) water
Raw Pressure Accuracy**
±0.3% FS, 2.55 kPa (0.37 psi) maximum error
Resolution
<0.085 kPa (0.012 psi), 0.87 cm (0.028 ft) water
Pressure Response Time***
<1 second to 90% at a stable temperature
Absolute Pressure and Water Level Measurements W-CTD-04
Range
0 to 145 kPa (0 to 21 psia); approximately 0 to 4 m (0 to 13 ft) of water depth at sea level, or 0 to 7 m (0 to 23 ft) of water at 3,000 m (10,000 ft) of altitude
Factory Calibrated Range
69 to 145 kPa (10 to 21 psia), 0° to 40°C (32° to 104°F)
Burst Pressure
310 kPa (45 psia) or 18 m (60 ft) depth
Water Level Accuracy*
Typical error: ±0.075% FS, 0.3 cm (0.01 ft) water
Maximum error: : ±0.15% FS, 0.6 cm (0.02 ft) water
Raw Pressure Accuracy**
±0.3% FS, 0.43 kPa (0.063 psi) maximum error
Resolution
<0.014 kPa (0.002 psi), 0.14 cm (0.005 ft) water
Pressure Response Time***
<1 second to 90% at a stable temperature
Temperature Measurements (All Models)
Range
-20° to 50°C (-40° to 122°F), non-freezing water
Accuracy
±0.15°C (±0.27°F) from 0° to 50°C (32° to 122°F)
Resolution
0.01°C at 25°C (0.018°F at 77°F)
Response Time
3 minutes to 90% in water (typical)
Drift
<0.1°C (0.18°F) per year
Sensor
Dimensions
2.5 cm (1 inch) diameter, 18.7 cm (7.37 inches) length
Weight
177g
6.24 oz
Wetted Materials
Passivated 316 Stainless steel housing rated for use in saltwater, Viton and Buna-N O-rings, PET sensor connector
Depth sensor: ceramic
Conductivity sensor: PET, platinum plating on electrodes
Note: Sensor should be mounted so that it is not in contact with other metals
Environmental Rating
IP68; Waterproof to pressure sensor burst pressure rating
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CE Compliance Mark
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UKCA (UK Conformity Assessed) Mark
* Water Level Accuracy: With accurate reference water level measurement, known water density, and a stable temperature environment. System Water Level Accuracy equals the sum of the Barometric Water Level Accuracy plus the selected CTD sensor Water Level Accuracy.
** Raw Pressure Accuracy: Absolute pressure sensor accuracy includes all sensor drift, temperature, and hysteresis-induced errors.
*** Changes in Temperature: Allow 20 minutes in water to achieve full temperature compensation of the pressure sensor. There can be up to 0.5% of additional error due to rapid temperature changes.