DO-957/958 Polarographic Dissolved Oxygen Sensor

Polarographic dissolved oxygen probe, positive electrode is silver(Ag) , negative electrode is platinum (Pt) or gold (Au), between them is full of electrolyte. In air-saturated water (20.9% Oxygen), the probe has an output from 400nA to 1000nA. The residual output in zero oxygen solutionislessthan1%oftheoutputinsaturatedwater.

When the measurement, the electrode with 675mV polarization voltage, oxygen permeation through the diaphragm in the cathode consumption, while the same amount of oxygen in the anode, the dynamic process

to both sides of the oxygen partial pressure to achieve the same balance between the two electrodes Of the current and oxygen partial pressure is proportional to the secondary table to detect this current, and then after a series of changes, get oxygen concentration and oxygen content.At the same time, NTC (negative temperature coefficient thermistor) to detect the measured liquid temperature, After sampling, the temperature is compensated and the oxygen concentration or oxygen content is converted to the value at 25 ° 

Negative reaction : O2+2H2O+4e→4OH

Positive reaction : 4Ag+4Cl-→4AgCl+4e

Mainly used for measurement of general dissolved oxygen,high measurement accuracy

One ATC probe is fitted to customers specific requirements. Replacing the membrane kit is quick and easy simply unscrew the old assembly, load the new one with fill solution and screw on to the probe. The probe is supplied complete with 3 membrane kits and a 30mL bottle of filling solution.

User guide of DO Probe

(1) The main material of electrode measuring terminal is ABS plastic, makesure that test solutions will not affect measuring terminal before measurement.

(2)  In measurement state, the probe will consume oxygen around gas-permeable membrane. So users need to stir the solution tosupply oxygen content when the measuring terminal is under solution.

(3)  The membrane can't suffer any damage,should try to avoid touching breathable membrane.

(4)  The membrane should full contact to the top of probe’s negative pole, without bubble, otherwise will affect accuracy of probe. If the membrane is damaged or is adhered with impurities,should replace new membrane in time.

(5)  Should change filling solution after aperiod of time use,the change frequency of filling solution is related to its service condition. It is suggested to change filling solution once a week if use probe most frequently.

(6)  The electrode cap,wire and connect or interface should avoid stress and any damage.

(7)  Must keep the connect or interface dry.

a) Grease cleaning: Immerse the probe in warm slightly alkaline detergent for 15min, then rinse with DI water.

b) Protein precipitation cleaning:Immersethe probe in 0.1mol/L hydrochlric solution contains 1% pepsin for 15min,then rinse with DI water.

c) Probe restoration: With fine sand paper, slightly polish the surface of platinum sheet, then rinse with DI water.

DO Probe Calibration

1) Full scale calibration There are two ways to calibrate full scale:

Calibrate in the air is for general user; calibrate in saturated dissolved oxygen water is for precision 

measurement. 

Calibrate in the air

a.Place the DO probe in air without obvious air turbulence and temperature fluctuation.

b.Check the surface of membrane without obvious water stain.

c.After the reading of temperature and DO become stable, calibrate according to instrument instructions. 

Calibrate insaturated dissolved oxygen water

a. Immerse the electrode measuring terminal in saturated dissolved oxygen water, wait the reading of 

temperature become stable.

b. Swing the probe in constant speed or use a stirrer to make saturated dissolved oxygen water has certain flow rate (when using a stirrer, slightly shake the probe to remove air bubbles on membrane). After the reading of DO becomes stable, calibrate according to instrument instructions.

2) Zero scale calibration

a. Dissolve12.5g analytical pure sodium sulfitein 250ml DI water,prepare oxygen-free water.

b. Immerse the electrode measuring terminal in oxygen-free water,slightly shake the probeto remove air 

bubbles on membrane.

c.After the reading of DO becomes stable,calibrate according to instrument instructions 

Package : Carton box package

Shipping : 5-7days

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