Hydrolab HL4

Multiparameter sonde


The HL4 is Hydrolab’s next-generation sonde and a replacement for the DS and MS series products.

  • SDI-12, RS-232, and RS-485 communication options
  • Self-monitoring system reports the status of the instrument, flags the data, and shows the user where the problem is with assistance on how to solve the issue
  • User-scheduled calibration and maintenance intervals indicate when they are due
  • Guided and semi-automated calibration routines lead the user through the calibration process
  • Calibration results are stored with date and time, calibration type, user identification, and user notes
  • Check Calibration process allows the user to verify calibration and store the results
  • Calibration reports contain information about previous calibrations and calibration checks
  • Sensor status is saved with every line of data and is contained in the log file
  • Dedicated communications modules allow easy integration with data loggers and telemetry systems
  • Sensors available:
    • Conductivity
    • LDO (luminescent dissolved oxygen)
    • Temperature
    • pH
    • Depth/Vented Level
    • Turbidity
    • ORP (Oxygen Redox Potential)

What's the Easiest and Quickest Way to Start Collecting Data and Access it Anywhere?

The Answer's in the Cloud.

eTracker is a cellular modem and "virtual" cloud-based data logger in one (meaning you don't need to install a separate data logger). Simply connect your sensor and a power source to eTracker and you're done. Configure (or reconfigure) anytime from any Internet-connected device, and use Stevens-Connect to retrieve your data, or forward it to your favorite software system.

Technical Specifications



6-30 VDC (12 VDC nominal) applied to the communications module, 12 VDC: 250 mW average, 19 W peak


(Optional) Internal alkaline D-cell battery, non-rechargeable.

Sleep mode at 12 V

20 mA


Hydrolab communications modules: USB, SDI-12, RS232, RS485, or TTY


4 GB of internal memory; 1 second interval minimum


Sonde depth rating

200 m (656 ft)

Maximum Deployment Cable

200 m (656 ft)

Diameter without bumpers

4.4 cm (1.75 in.)

Diameter with bumpers

5.3 cm (2.1 in.)

Weight with internal battery pack (IBP) and storage/calibration cup

2.2 kg (5 lb)

Length - no IBP, standard sensor guard

51.4 cm (20.25 in.)

Length - no IBP, extended sensor guard

66.4 cm (26.125 in.)

Length - IBP and standard sensor guard

62.2cm (24.5 in.)

Length - IBP and extended sensor guard

77.8 cm (30.625 in.)

Environmental conditions

Operating temperature

-5 °C to 50 °C (23 °F to 122 °F), non-freezing

Storage temperature

1 °C to 50 °C (34 °F to 122 °F)