B&C Electronics OD 205.2 Instruction Manual

CERT. N. 9115 BCEL

INSTRUCTION MANUAL

UNI EN ISO 9001:2000

OD 205.2

DISSOLVED OXYGEN METER

Rev. B - 03/07

B&C Electronics Srl - Via per Villanova 3 - 20040 Carnate (Mi) - Italy - P.IVA 00729030965
Tel [phone] - Fax [phone] – [e-mail] - www.bc-electronics.it

B&C Electronics OD 205.2

Index

1 GENERAL INFORMATION....................................................................................................... 3

2 PRINCIPLES ................................................................................................................................ 3

3 FUNCTIONAL DESCRIPTION .................................................................................................. 4

4 PHYSICAL DESCRIPTION ........................................................................................................ 5

5 SPECIFICATIONS....................................................................................................................... 6

6 ELECTRICAL INSTALLATION ................................................................................................ 7

6.1 Connecting the power.......................................................................................................... 7

6.2 Warnings.............................................................................................................................. 7

6.3 Connecting the cell .............................................................................................................. 7

6.4 Connecting a recorder.......................................................................................................... 7

6.5 Connecting the RTD............................................................................................................ 8

6.6 Checking.............................................................................................................................. 8

7 OPERATING THE SYSTEM ...................................................................................................... 9

7.1 Pre-operation check ............................................................................................................. 9

8 NORMAL OPERATION............................................................................................................ 10

9 CALIBRATING THE METER .................................................................................................. 11

9.1 Electric zero....................................................................................................................... 11

9.2 zero cell calibration............................................................................................................ 11

9.3 slope calibration................................................................................................................. 11

9.4 polarization Voltage of sensor........................................................................................... 11

10 TEMPERATURE COMPENSATION ....................................................................................... 12

10.1 Manual ............................................................................................................................... 12

10.2 automatic ........................................................................................................................... 12

11 PREVENTIVE MAINTENANCE.............................................................................................. 13

11.1 meter .................................................................................................................................. 13

11.2 Sensor ................................................................................................................................ 13

12 TROUBLESHOOTING GUIDE ................................................................................................ 14

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B&C Electronics OD 205.2

1 GENERAL INFORMATION

This manual applies to the bench OD 205.2 digital Oxygen meter. It explains the purpose of the
equipment, describes the components of the series and the procedures for installing the equipment,
operating it and calibrating it.

Some suggestions are also given for its maintenance.

2 PRINCIPLES

In a polarographic cell, if a constant Voltage is applied to the electrodes, the reduction of the Oxygen
ions on the cathode generates a current proportional to the oxygen's partial pressure.

The intensity of the current produced at a constant Temperature and at a given Oxygen pressure
depends on the quantity and composition of the electrolyte, the cathode's area and the sample's state.
Response time depends on the electrolyte's and diaphram's characteristics. The value of the applied
Voltage to the anode is chosen in a way that only Oxygen can react.

In absence of Oxygen, the current produced is not exactly zero. In fact, impurities and other factors
generate a "dark current" which can be offsetted by the amplifier.

The electrode consumes the Oxygen diffused through the permeable membrane and the electrolyte's
film, therefore a concentration gradient is established between cathode and sample; the electrodes with
a big cathode and with a high output current, consume a lot of Oxygen and are more sensitive to the
sample's flow and therefore request a large flow and an adequate stirring of the sample.

The Temperature dependance of the output current is compensated by the automatic or manual
Temperature compensation of the meter.

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B&C Electronics OD 205.2

3 FUNCTIONAL DESCRIPTION

This series of bench dissolved Oxygen meters is specifically designed for laboratory and fermentation
processes.

The unit provides a digital readout of the dissolved Oxygen in aqueous solutions.
In order to satisfy the many requests of such measurements, four different ranges have been designed
and may be selected on the meter:

- % Oxygen saturation

- % air saturation

- mm Hg

- mg/l (ppm)

RTD automatic Temperature compensation and manual compensation are employed to provide highly
accurate measurements over the entire ranges of dissolved Oxygen and Temperature values. The
Temperature value and the Temperature coefficient value are both visualized on the display by
pushing the corresponding lever on the front panel.

A basic O2 monitoring system consists of two elements: a monitoring unit, and a probe or O2 cell.
The system can be expanded by adding accessories for field applications, recorders, secondary
regulators, proportional regulators, special probes and Temperature probes to suit particular
applications.

The meter contains electronic circuits to control the operations of the entire system.
It provides a digital readout of Oxygen on a 3 1/2 digit display and an output of 0/20 mA or 4/20 mA
(selected by a switch on the rear panel) proportional to the meter reading, for driving a recorder,
remote readout or regulators having a not grounded input.

Zero and slope are calibrated by trimmers on the front panel.

Automatic Temperature compensation is carried out by means of a RTD Pt 100.

The meter's input is by a BNC connector for the Oxygen cell and by a phone Jack for the RTD.

The digital Temperature readout, both in the manual and the automatic Temperature operation, is
obtained by pushing a lever 10 on front panel, as measuring and output functions of the instrument
are not altered.
The manual Temperature compensation is adjusted by the trimmer 11.
The digital readout of Temperature coefficient ( % / °C ), both in the manual and the automatic
operation is obtained by pushing a lever 12, its value being adjusted by the trimmer 13.

The scale is chosen by the selector 14 and the corresponding Led 15 shows which scale is operating.

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B&C Electronics OD 205.2

4 PHYSICAL DESCRIPTION

The meter's case consists of an anodized aluminium front panel and an epoxidic-coated metallic case,
to ensure the maximum anticorrosion characteristics.

Connections to the power supply, recorders, RTD, electrodes or probes are carried out by means of
sockets or connectors on the rear side.

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B&C Electronics OD 205.2

5 SPECIFICATIONS

Voltage: 110 or 220 Volts (as requested) +/-10 % 50/60 Hz

Input: from polarographic O2 cell

Output: 0/20 mA dc, non isolated, 300 ohm max.
4/20 mA or others on request

Scales: 0.0/199.9 % O2

0.0/199.9 % air saturation

0.0/199.9 mm Hg

0.0/19.99 ppm

Zero: adjustment +/- 15%
Slope: fine adjustment +/- 20%
coarse adjust. 5 to 50 nAmp air saturation at 20°C

Cell Voltage: 675 mV
Cell current in air: approx. 0.030 microAmp.
Cell connector: BNC
Factory calibration: half scale with 0.030 microAmp.input

Temperature: 0/50 °C
Temperature compensation: manual and automatic 0/50 °C
Temperature coefficient: 0 to 6 %/°C
Temperature sensor: RTD Pt100
Temperature readout: -20/+120 °C

Circuit fuse: 80 mA T (110 V)
32 mA T (220 V)

Power: 3 VA
Weight: 2.000 Kg
Dimensions: 215 x 95 x 200 mm

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