HI-6000-4 DO MODULE FOR HI-6000 SERIES BENCH MULTIPARAMETER

HI6000-4 Dissolved Oxygen module is designed to be used with the HI6000 Multiparameter Modular System for fresh and saltwater measurements of dissolved oxygen when used with the HI7641133 optical dissolved oxygen (opdo®) probe or the HI764833 polarographic dissolved oxygen probe.

The Oxygen Uptake Rate (OUR), Specific Oxygen Uptake Rate (SOUR), Oxygen Demand (BOD) methods guide the user through the procedures adhering to the standard method guidelines.

Concentration measurements are automatically compensated for barometric pressure, temperature, and salinity.

• OUR measurements determine the biological activity of a system in terms of oxygen consumption or respiration rate.

• SOUR measurements determine the oxygen consumption of a system.

• BOD measurements determine the oxygen uptake rate by microorganisms in a water sample over a period time

Measurement

• Choice of Measurement Unit

• DO – %Sat, mg/L, ppm

• BOD – ppm, mg/L

• OUR – ppm, mg/L

• SOUR – ppm, mg/L

• Pressure – mmHg, mbar, kPa, inHg, psi, atm

• Reading modes: direct and direct/autohold; BOD, OUR, SOUR

Calibration

• One or two points automatic calibration at 100.0 % (8.26 mg/L) and 0.0 % (0.00 mg/L)

• One point manual calibration using a valued entered by the user.

Recommended probes

Hanna recommends a choice of 2 dissolved oxygen probes for use with this module: HI7641133 optical dissolved oxygen probe (opdo®) and HI764833 polarographic probe.

HI7641133 opdo probe (with HI764113-1 Smart Cap) provides accurate dissolved oxygen measurements over long periods of time reducing the need for frequent calibration. The Cap, pre-loaded with calibration coefficients, includes the immobilized O2 sensitive luminophore with a rugged, insoluble black oxygen permeable protective layer.

The principle of operation is based on the principle of fluorescence quenching and features an immobilized Pt-based luminophore that is excited by the light of a blue LED and emits a red light. Dissolved oxygen quenches this excitation. When there is no oxygen present, the lifetime of the signal is the greatest; as oxygen hits the sensing surface, the lifetime becomes shorter.

The intensity and lifetime are inversely proportional to the amount of oxygen present; as oxygen interacts with the luminophore it reduces the intensity and lifetime of the luminescence. The lifetime of the luminescence is measured by a photodetector, and is used to calculate the dissolved oxygen concentration. This is, in turn, reported by the meter as % saturation or mg/L of dissolved oxygen.

HI764833 Clark-Type polarographic probe features a platinum cathode and Ag/AgCl anode assembly and a built-in temperature sensor. The temperature measurement is used in computations for dissolved oxygen measurements.

The probe has a thin, 12 mm (0.47”), design that allows for convenient measurement in narrow vessels such as test tubes, wine bottles, standard BOD bottles. The probe is fitted with a PTFE screw cap membrane that separates the probe’s cathode and anode from the sample being measured. Oxygen diffuses across the membrane and interacts with the polarographic system to produce a current proportional to oxygen concentration. The cap is filled with HI7041 electrolyte and screwed on to the probe. Screw-on caps with pretensioned membranes provide quick maintenance.