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 Water analysis >
Oxygen meter Hach
  > Printable version

The HQ10 and HQ20 portable dissolved oxygen meters are based on new technology, the Hach LDO® Sensor.

For more than 50 years, portable meters using galvanic and polarographic sensors have been used to measure dissolved oxygen. Unfortunately, these sensors rely on delicate membranes, anodes, cathodes, and electrolyte solutions, which experience high failure rates:

  • Anodes are consumed over time, and periodic replacement can be inconvenient and costly
  • Electrolytes are consumed, are subject to contamination, and must also be replaced
  • Gases like hydrogen sulfide can poison the anode and electrolyte, necessitating replacement
  • Sensor membranes become coated with grease and dirt and require regular cleaning, risking membrane rupture and the need for replacement
  HQ10 Portable LDO Dissolved Oxygen Meter

Electrolyte depletion and anode breakdown make regular sensor calibration necessary. Maintenance tasks to keep your portable DO meters functioning take time and cost money.

Even if regular maintenance is performed, there's no guarantee that you'll get accurate results. Galvanic and polarographic DO measurements are subject to interference from anything that produces a voltage, including ferric chloride, ferrous sulfate, aluminum sulfate, and polymers. Changes in pH can also affect DO readings.

How do luminescent dissolved oxygen  (LDO) sensors work?
The HACH LDO sensor is coated with a luminescent material. Blue light from an LED is transmitted to the sensor surface and excites the luminescent material. As the luminescent material relaxes it emits red light. This red luminescence of the sensor is proportional to the dissolved oxygen present.  A red LED is incorporated into the sensor as an internal reference.

How does this benefit you?

  • No anode, electrolyte, or membrane to replace
  • Stable output (no drift) which eliminates the need for frequent calibrations
  • 1-year between sensor replacements
  • No fragile membrane that can rupture
  • No probe polarization waiting time--instant on

The HQ10 Portable LDO Dissolved Oxygen Meter, and the HQ20 Portable LDO Dissolved Oxygen/pH/mV Meter are rugged and easy to use.  Accurate results are achieved reliably and reproducibly.  A built in barometer corrects measurements for pressure variations; the built in temperature sensor corrects for temperature variations; and salinity corrections can also be applied.  The meter and LDO Probe come with a 3-year warranty, and are backed by Hach's excellent technical support.  The sensor is warranted for 1-year of service life.


Probe Materials: Polycarbonate/ABS blend
Sensor Materials: Polymethyl methacrolate (Acrylic)
Temperature Sensor: 30K Ohm Thermistor
Temperature Compensation: Automatic (32 to 122°F, 0 to 50°C)
Pressure Compensation: Automatic (400 to 1100 mBar)
Salinity Correction: Automatic (0 to 70 ppt)
Minimum Flow Rate: Negligible, < 2 inches/minute (<5 cm/minute)
Measuring Range: Dissolved Oxygen Measurement:
0.01 to 20.00 mg/L (ppm); 0 to 200% saturation
Temperature Measurement:
32° to 122° F (0.0° to 50° C)
Pressure Measurement:
400 to 1100 mBar
Resolution: Dissolved Oxygen:
0.01 mg/L (ppm) 0.01% saturation
0.1 °F/°C
1 mBar
Accuracy: Dissolved Oxygen:
± 0.1 mg/L @ < 8 mg/L; ± 0.2 mg/L @ > 8 mg/L
± 0.3°C
± 2% of reading
Sensitivity: ± 0.05% of Span
Detection Limit: 0.01 mg/L (ppm), estimated
Response Time at 20° C: To 95% of measured value, <30 seconds
Sensor Cable Lengths: 1-meter (40"), 3-meter (10´), 5-meter (16´), 15-meter (50´) are available
Measuring Principal: Luminescence decay rate
Interferences: No interferences noted at concentrations typically found in DW and WW.
Species evaluated include: H2S, pH, Na+1, Al+3, Fe+2, Fe+3, SO4-2, Cl-1, Cl2, ClO2, Oil (oil did slow response)
Probe Warranty: 3 Years
Sensor Warranty: 1-year service life, plus 1-year storage life
Instrument Warranty: 3 Years
Environmental Conditions: Operation:
32° to 122° F (0.0° to 50° C); 0 to 95% non-condensing relative humidity
-4 to +140°F (-20 to +60°C); 0 to 95% non-condensing relative humidity
Display: Graphic dot matrix LCD, 160x160 pixels with electroluminescent (EL) backlighting
Power Requirements: Docking Station:
36-12 V dc; use Hach-supplied 115 or 230 V, 50/60 Hz external power with 330 mA output, 5.5-mm power plug with a 2.5 mm center post (positive).
4 AA alkaline batteries, or power through the docking station
Battery Life: Dissolved Oxygen Mode:
Approximately 3 months with typical use or 12 hours in continuous mode
pH Mode (HQ20 Only):
Approximately 6 months with typical use or 240 hours in continuous mode
Low Battery Indicator: Yes
Meter dimensions: 21.2 x 8.7 x 4.2 cm (8.35 x 3.43 x 1.65 inches)
Net Weight: Instrument: 0.86 lbs. (391g)
Enclosure: Waterproof designed to meet IP67, chemical resistant, dust proof; meter will float; probe/meter connection requires drying out if wetted. Docking station is water-resistant to IP40.
Installation Category: II (for 115 V and 230 V external docking station power supplies)
D.O. Calibration Methods: Factory Cal:
Sensor calibration is downloaded from RS232 module to meter
Sample Cal:
Enter one sample value derived by laboratory analysis or comparison reading.
Air Cal:
For use when the sensor is calibrated in water saturated air.
Meter Communication: Inputs:
(1) 5-pin Hach LDO probe connector (HQ10 and HQ20)
(1) 5-pin Hach pH/mV/temperature probe connector (HQ20 only)
RS-232 via docking station to printer/PC;
User selectable timed interval output,10 second to 30 minute intervals
Internal Data Logging: User selectable time intervals from 10-seconds to 30-minutes
User selectable durations from 15 minutes to 48 hours.
Memory (non-volatile): All user settings and data are retained in non-volatile memory
The meter stores 500 data records
EMI/RFI Conformance: Exceeds U.S. and meets European standards for conducted and radiated emissions and immunity; certified CE compliant for applications as specified by EN 50081-1 for emissions and EN 50082-2 for immunity
Probe Chemical Resistance: For aqueous solutions only. Do not immerse in organic solvents or alcohols.
Meter Chemical Resistance: Resistant to alcohols, acids and bases. Do not expose to organic solvents.

Rigid Carrying case
99.00 $
Hach oxymeter with 3 meter cable & pH probe.
3,300.00 $
Hach oxymeter with 5 meter cable.
1,685.00 $
Replacement cap.
230.00 $
Hach oxymeter with 15 meter cable & pH probe.
3,300.00 $
Hach oxymeter with 3 meter cable.
1,685.00 $
Hach oxymeter with 15 meter cable.
1,685.00 $
Hach oxymeter with 5 meter cable & pH probe.
3,300.00 $
Last Update: November 26 2004
Prices are in canadian dollars and can change without notice.

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788, Blv. Methot, St-Nicolas (QC) CANADA - G7A 3W4 - Toll Free : (888) 278-4776 - Fax : (418) 831-2882