View All Sea Bird View All Hydrolab Products View All OTT Products View All ADCON Products View All Van Essen Products View All Eijkelkamp Products View All Turner Products View All Turner Products

Know the instrument is working correctly and troubleshoot quickly. Streamline calibration tasks and produce valid, scientifically defensible conclusions.

Use with the Hydrolab Surveyor HL for attended monitoring, or for unattended continuous monitoring applications, the HL4 has on-board data logging and dedicated communications modules for easy integration with external loggers and telemetry.

Product type: Attended, Unattended
Parameters measured: Temperature, Conductivity, Depth, pH, Dissolved Oxygen (LDO), Turbidity (Self Cleaning)
Product highlights: The next generation multiparameter water quality instrument
Interface: SDI-12, RS-485, RS-232, TTY, USB

  • 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
  • Compatible with the Surveyor HL – a fully IP67 handheld designed for field use with a full-color screen that is visible in direct sunlight



Temperature sensor and up to four additional sensors plus depth and ORP




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

User Interface


PC Software

Hydrolab Operating Software


(Optional) Hydrolab Surveyor HL



Sonde Depth Rating

200 m (656 ft)

Maximum Deployment Cable

200 m (656 ft)

Diameter w/o bumpers

4.4 cm (1.75 in.)

Diameter with bumbers

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

Storage temperature

1 ... 50 °C (34 ... 122 °F)

Related Categories
Water Quality Sensors
Aqualab Systems
Handheld Communications