Hanna Instruments Worldwide
The Hanna Advantage: A Worldwide Leader in Technology and Innovation 100% Quality  360 Value
Contact Hanna: +1 (800) 426-6287

Advanced Dissolved Oxygen Benchtop Meter with Polarographic DO Probe - HI6421P

Ships within 24 hours (business days)

SKU: HI6421P-02 Categories ,


GST and Shipping charges are extra

HI6421P is a streamlined dissolved oxygen benchtop meter supplied with Hanna’s polarographic oxygen probe and features a large touch screen display for fresh and saltwater measurements.


Ships within 24 hours (business days)


  Add to wish list

HI6421P is a streamlined benchtop meter with a large touch screen display, comprised of a housing and an integrated module designed for fresh and saltwater measurements of dissolved oxygen.

HI6421P includes the HI764833 polarographic probe. Slim and versatile, this probe covers a wide range of dissolved oxygen and has a built-in thermistor temperature sensor that compensates for temperature variations. The slim design allows for convenient measurement in test tubes and Biological Oxygen Demand (BOD) bottles.

Durable and robust, the probe features a platinum cathode and Ag/AgCl anode assembly. Accurate and with a fast response time, readings are not flow dependent.
The probe is fitted with durable (PTFE), oxygen permeable, screw on membrane caps. Caps are filled with electrolyte and easily installed on the probe.

Concentration measurements are automatically compensated for barometric pressure, temperature, and salinity. Barometric pressure and temperature are automatically measured and compensated. Salinity is automatically compensated by setting manually the salinity concentration of the water being measured.

Additional features include built-in methods and calculations for the measurement of BOD (Biological Oxygen Demand), OUR (Oxygen Uptake Rate), and SOUR (Specific Oxygen Update Rate).

Pressure compensation is done automatically (built-in barometer) or users have the option to manually enter required value. Pressure is displayed in user-configurable units: mmHg, mbar, kPa, inHg, psi, atm.


Features at-a-glance

User interface

  • 7-inch capacitive touch screen with multi-touch support
  • Capacitive touch back, home and system menu keys
  • User-friendly icons and symbols allow users to easily navigate and interpret the instrument functions

The user can select between five different views:

  • Basic measurement configuration
  • Simple GLP with calibration information
  • Full GLP with electrode status and calibration point details
  • Live updated, interactive graph
  • Tabulated data with date, time, and notes


  • Measure %Sat, mg/L, ppm (DO); mg/L, ppm (BOD); mg/L (OUR); ppm, mg/L (SOUR)
  • Application-specific profiles allow quick and direct measurement without the need to update the
    sensor and system settings
  • Active log during measurement Measurement stability indicator (using the Stability Criteria setting)
  • Reading modes: direct and direct/auto-hold
  • Temperature compensation can be Automatic or set manually
  • Audible and/or alarm messages for measurements outside of predefined limits
  • Galvanic isolation for measurement


  • One or two points calibration at 0% and/or 100% saturation
  • Single point manual calibration in mg/L or % saturation using a reference method
  • Non-volatile memory saves data and settings


  • Data log collection of at least 1, 000, 000 data points (with time and date stamp)
  • Logging types: manual, automatic, auto-hold
  • Sample ID for manual and auto-hold data

Connectivity features & services

  • Transfer logged data ta USB thumb drive
  • Log files that include measurements and calibration data (as .csv file)
  • FTP and email for log export via Ethernet and Wi-Fi connection
  • USB type A for USB stick, keyboard, and printer
  • USB type C for USB stick and PC connection

Help section for meter guidance

  • Video support presentation of main functionalities

Primary Applications:

Fresh water and saltwater applications, aquaculture, aquariums, environmental.

Ordering Information:

HI6421P is supplied with HI764833 polarographic probe; HI764060 electrode holder; capillary pipette; 24 VDC power adapter; USB-C to USB-A cable; probe quality certificate; quick reference guide with instrument quality certificate.

Name Advanced Dissolved Oxygen Benchtop Meter with Polarographic DO Probe – HI6421P
DO (HI764833 Polarographic probe) Range 0.00 to 90.00 mg/L (ppm) concentration; 0.0 to 600.0 % saturation
DO (HI764833 Polarographic probe) Resolution 0.01 mg/L (ppm); 0.1 % saturation
DO (HI764833 Polarographic probe) Accuracy ±1.5 % of reading ±1, least significant digit
Barometric Pressure Range 450 to 850 mmHg; 600 to 1133 mBar; 60 to 133 kPa; / 17 to 33 inHg; 8.7 to 16.4 psi; 0.592 to 1.118 atm
Barometric Pressure Resolution 1 mmHg; 1 mBar; 1 kPa; 1 inHg; 0.1 psi; 0.001 atm
Barometric Pressure Accuracy ±3 mmHg within ±15 % from the calibration point / ±3 mmHg ±1 least significant digit
Temperature Range −20.0 to 120.0 °C / −4.0 to 248.0 °F / 253.0 to 393.0 K
Temperature Resolution 0.1 °C; 0.1 °F; 0.1 K
Temperature Accuracy ±0.2 °C; ±0.4 °F; ±0.2 K
DO Calibration Points Automatic-two points / User standard-single point
DO Calibration Standards 0 and 100% saturation
DO Calibration Reminder Disabled / Daily: 0 m in. to 23 hours and 59 m in. / Periodic: 1 m in. to 500 days, 23 hours and 59 m in.
Temperature Compensation Automatic or Manual
Reading Modes Direct Direct/Autohold
Reading Stability criteria Accurate Medium Fast
Reading Isopotential 7.000 or 4.010
Reading Sampling rate 1000 ms
DO Views Basic Measurement (DO, Temperature) Stability status
DO Views Simple GLP Basic view information Last calibration date, offset, average slope
DO Views Full GLP Simple GLP information and calibration point details
DO Views Table Measurements updated every second are displayed in table
DO Views Graph (Plot) Measurement versus time graph can be panned or zoomed (pinch-to-zoom technology)
Logging Type Automatic, Manual, Autohold
Logging Number of records 50 000 maximum per file Stores at least 1 000 000 data points per user
Logging Automatic interval 1, 2, 5, 10, 30 seconds / 1, 2, 5, 10, 15, 30, 60, 120, 150, 180 minutes
Logging Sample ID Incremental mode
Logging Export option .csv file format
Users Up to 9 users and the default administrator account
Connectivity USB-A 2 ports for keyboard input or USB thumb drive
Connectivity USB-C 1 port for PC connectivity and USB-C type thumb drive
Connectivity Wi-Fi & Ethernet FTP / Web server Log transfer and download Email
Connectivity RS232 Connecting peripherals
Power supply DC adapter 100-240AC to 24VDC 2.5A
Environment 0 – 50 °C / 32 – 122 °F / 273 – 323 K maximum 95% RH non-condensing
Dimensions 205 x 160 x 77 mm (8.0 x 6.2 x 3.0 “)
Weight Approximately 1.2 kg (26.5 lbs.)

Advanced Dissolved Oxygen Benchtop Meter with Polarographic DO Probe – HI6421P


There are no reviews yet.

Be the first to review “Advanced Dissolved Oxygen Benchtop Meter with Polarographic DO Probe – HI6421P”

Your email address will not be published. Required fields are marked *