Vzor MARK-302T User manual

MARK-302Т
DISSOLVED
OXYGEN
METER
Operation Manual
Nizhny Novgorod
2010
АЯ 74

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VZOR will appreciate any suggestions and comments aimed
at product quality improvement.
If you have any trouble with the instrument performance,
please contact us in writing or by phone.
Postal address: 603106, Russia, Nizhny Novgorod, POB 253
Telephone: + 7 [phone], 412-29-40
E-mail: [e-mail]
Website: www.vzornn.com

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C O N T E N T S
1 DESCRIPTION AND OPERATION ....................................................................... 4
1.1 Purpose ............................................................................................................ 4
1.2 Basic parameters ............................................................................................. 4
1.3 Specifications ................................................................................................... 6
1.4 Product components ........................................................................................ 7
1.5 Description and operation ................................................................................ 7
1.6 Measuring instruments, tools and accessories ................................................ 9
2 INTENDED USE .................................................................................................. 10
2.1 Operating limitations ...................................................................................... 10
2.2 Safety ............................................................................................................. 10
2.3 Pre-starting procedures ................................................................................. 10
2.4 Measurement procedure ................................................................................ 15
2.5 Functional check ............................................................................................ 18
2.6 Troubleshooting ............................................................................................. 19
3 MAINTENANCE ................................................................................................... 26
4 DELIVERY SET ................................................................................................... 26
APPENDIX A. Solubility of 100 % humidity air oxygen in distilled water,
depending on the temperature ............................................................................ 27

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1 DESCRIPTION AND OPERATION
1.1 Purpose
1.1.1 Product name and designation
MARK-302Т dissolved oxygen analyzer
TU 4215-022-39232169-2008.
1.1.2 The analyzer has been designed to measure the dissolved oxygen
concentration and water temperature.
1.1.3 The analyzer’s scope of application is high-sensitivity measurement of
the mass concentration of dissolved oxygen (in the microgram range). It is used
primarily at heat power facilities for deaerated water monitoring.
1.1.4 The analyzer may also be used to measure the mass concentration of
water-dissolved oxygen and temperature of surface, waste and potable water, and
may be employed by fish farms; chemical, biotechnological and food industries;
educational institutions and ecology branches.
1.1.5 The type of analyzer:
 amperometric;
 with external poling voltage;
 with one sensitive element;
 with a digital LCD display;
 with automatic temperature compensation;
 with flow-type/ dip sensor;
 with automatic calibration when the sensor is placed in the oxygen envi-
ronment (air) at temperatures varying between +15 °С and +35 °С;
 with automatic adjustment for atmospheric pressure during calibration.
1.2 Basic parameters
1.2.1 By resistance to climatic effects, the analyzer version group is B4 in
accordance with GOST 12997-84.
1.2.2 By resistance to mechanical effects, the analyzer version is L1 in ac-
cordance with GOST 12997-84.
1.2.3 The converter unit degree of protection ensured by the casing is IP30
in accordance with GOST 14254-96.
1.2.4 By resistance to atmospheric pressure, the analyzer version group is
Р1 in accordance with GOST 12997-84 (atmospheric pressure between 84 and
106.7 kPa).

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1.2.5 Analyzed water parameters:
 temperature, °С ………………………………………………….…... 0 to +50;
 pressure, MPa, max ……...………………………………..….……....… 0.05;
 salt content, g/dm3 ……...………………………..………..……..…... 0 to 40;
 рН ……………………………………………………….…….….......... 4 to 12;
 rate of water flow via flowing vat, cm3/min ............……………. 400 to 800;
 rate of water flow relative to sensor membrane, cm/s ….…………...…... 5.
1.2.6 Permissible concentrations of unmeasured components:
 dissolved ammonia, mg/dm3, max ….…...…………………..……….... 40.0;
 dissolved phenol, mg/dm3, max ….………….………………..…………. 0.2.
1.2.7 Operating conditions:
 ambient air temperature, °C ……………………………...………... +1 to +50;
 relative air humidity at 35 °С and lower temperatures without moisture
condensation, %, max …………………….………................................................. 80;
 atmospheric pressure, kPa (mm hg) ……………..………..…..84.0 to 106.7
(630 to 800).
1.2.8 The analyzer is calibrated by air of 100 % humidity.
Calibration temperature range, °С ………………………………..… +15 to +35.
1.2.9 The analyzer is powered from a 2,2-3,4 V DC self-contained power
supply (two AA-type alkaline batteries).
1.2.10 Power consumption (at a rated voltage of 2,8 V), mW, max ….…... 10.
1.2.11 The analyzer retains its characteristics within the ranges set in the
analyzer specifications after replacement of the sensor’s spare parts, batteries and
calibration.
1.2.12 The overall dimensions and weights of analyzer components are
summarized in Table 1.1 below.
Table 1.1
Name and designation of component versions Overall dimensions,
mm, max
Weight,
kg, max
ВР29.01.000 converter unit 84×160×38 0,30
ВР29.02.000 oxygen sensor (without cable)

16×115 0,12
ВР29.03.000 flowing vat 18×40×121 0,10
1.2.13 GOST 12997-84 conditions for carriage in shipping containers:
 temperature, °С ……………………...............…………..….…. – 20 to +50;
 relative air humidity at 35 °С, % ............................…….....………...… 95±3;
 5-35 Hz sinusoidal vibration with a 0.35 mm shift amplitude in the direction
marked “Top. Do not turn over” on the package.

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1.3 Specifications
1.3.1 DOC (dissolved oxygen concentration) measuring range at an analyte
temperature of 20 °С, mg/dm3 ..………………………………….……..….. 0 to 10,00.
The upper limits of DOC measuring range, depending on the analyte tem-
perature, are shown in Table 1.2.
Table 1.2
t, °C 0 5 10 15 20 25 30 35 40 45 50
DOC,
mg/dm3 17,45
15,29 13,48 12,10 10,00 9,85 8,98 8,30 7,69 7,12 6,59
1.3.2 Limits of the analyzer allowable basic absolute error in DOC measure-
ment at an analyte temperature of (20,0±0,2) °С and ambient temperature of
(20±5) °С, mg/dm3 ……………………………….…........................... ±(0,003+0,04С),
where С, here and hereafter, is a measured DOC value in mg/dm3.
1.3.3 Limits of the analyzer allowable additional absolute error in DOC
measurement due to a change in the ambient temperature, by each ±5 °С from the
normal temperature (20,0±0,2) °С, within the operating temperature range from 0
to +50 °С, mg/dm3 ……………………………………….….…………………. ±0,012C.
1.3.4 Limits of the analyzer allowable additional absolute error in DOC
measurement due to a change in the ambient temperature by each ±10 °С from
the normal temperature (20±5) °С, within the operating temperature range from +1
to +50 °С, mg/dm3 ….……….............................................................
±(0,001+0,002C).
1.3.5 Limits of the analyzer allowable absolute error in DOC measurement at
an analyte temperature coinciding with the calibration temperature which varies be-
tween +15 °С and +35 °С, at an ambient temperature of (20±5) °С,
mg/dm3……….…………………………………………...................... ± (0,003+0,04C).
1.3.6 Analyte temperature measuring range, °С ……...……............. 0 to +50.
1.3.7 Limits of the analyzer allowable basic absolute error in analyte temper-
ature measurement at an ambient temperature of (20±5) °С, °C ….……...…... ±0,3.
1.3.8 Limits of the analyzer allowable basic absolute error in analyte temper-
ature measurement due to a change in the ambient temperature by each ±10 °С
from the normal temperature (20±5) °С, within the operating temperature range
from +1 to +50 °С, °С …….....………………………..…………….…………..….. ±0,1.
1.3.9 Limit of the permissible value of the analyzer readout setting time t0.9 in
DOC measurement, min …………..……….…………………………….…………… 2.
1.3.10 1.3.10 Limit of the permissible value of the analyzer readout setting
time tу in DOC measurement, min ……….…………......................…………..…… 30.
1.3.11 Limit of the permissible value of the analyzer readout setting time t0.9
in analyte temperature measurement, min ……………………….………….………. 1.
1.3.12 Limit of the permissible value of the analyzer readout setting time tу in
analyte temperature measurement, min ………………………………………….….. 3.

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1.3.13 Analyzer oscillatory readings in DOC measurement for 8 h, mg/dm3,
max ……………………………………………………………..….….. ±(0,0015+0,02C).
1.4 Product components
The analyzer comprises:
 converter unit;
 oxygen sensor with a 2 m connecting cable;
 flowing vat.
1.5 Description and operation
1.5.1 General analyzer data
The MARK-302Т dissolved oxygen analyzer is a small-size microprocessor
device designed to measure the mass concentration of water-dissolved oxygen
(DOC) and the analyte temperature.
The DOC values measured in mg/dm3 or temperature measured in Celsius
degrees (depending on the measuring mode) are displayed on the readout device
– a digital LCD display (“the display”). The minimum value of the least significant
digit for DOC measurement is 0,001 mg/dm3. The least significant digit value for
temperature measurement is 0,1 °С.
The analyzer is calibrated by atmospheric air of 100 % humidity with auto-
matic adjustment for atmospheric pressure during calibration.
Adjustment for atmospheric pressure during the analyzer calibration by at-
mospheric air is provided by a built-in atmospheric pressure sensor.
1.5.2 Analyzer operating principle
The analyzer uses an amperometric sensor operating as a closed-type
polarographic cell. The electrodes are submerged in an internal electrolyte solution
which is separated from the analyte by a membrane penetrable for oxygen but im-
penetrable for liquid and water vapor. From the analyte, oxygen diffuses through
the membrane into a thin layer of electrolyte between the electrodes and the mem-
brane and undergoes an electrochemical reaction on the surface of the cathode
which is polarized by external voltage applied cross the electrodes. In the process,
the sensor generates a DC signal which is at a fixed temperature proportional to

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DOC in the analyte.
The analyzer features a temperature sensor (platinum thermal resistor) to
measure temperature and to automatically compensate for the temperature de-
pendence of the oxygen sensor signal. The temperature sensor signal is supplied
to the ADC input.
The ADC converts signals of the oxygen sensor and the temperature sensor
into codes incoming the microcontroller.
The microcontroller processes the codes received and shows the information
on the digital LCD display.
1.5.3 Analyzer design
The analyzer is shown in Fig.1.1а.
Converter unit 1 has a sealed plastic housing and is designed to convert sig-
nals from oxygen sensor 2 and display measurement data.
The front panel of the converter unit features:
 indicator screen 3 designed to display a measured DOC value or temper-
ature (depending on the chosen measuring mode), battery charge and current time
(in off state);
 button 4.
The back panel of the converter unit features a battery compartment cover.
Located on top of the converter unit is sealed cable entry 5 for oxygen sen-
sor 2.
а b
Fig. 1.1
1
3
15
2
4
5
12
11
13
14
8
9
10
7
16
6
17
MODE
CAL
ENTER

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Flow measurements use flowing vat 6.
Fig.1.1b shows the oxygen sensor design.
The sensor’s basic functional elements are platinum cathode 7 and silver
anode 8. Secured to cathode 7 with caprone thread 9 is teflon film 10. The mem-
brane and rubber bushing form membrane assembly 11 fitted over bushing 12 and
filled with electrolyte 13. The temperature sensor is enclosed in case 14. Protective
bushing 15 covers the sensor electrode portion and is screwed into cable bushing
16 (Fig.1.1а).
Cable 17 connects the sensor electrode assembly to the converter unit.
Made of a corrosion resistant alloy, flowing vat 6 is a threaded cylinder with
supply and drain connections for controlled water. To install the oxygen sensor in
the flowing vat, replace protection bushing 15 with flowing vat 6.
1.5.4 Functions of buttons on the converter unit front panel
The analyzer front panel features the following buttons as shown in Fig.1.1а:
 the button for analyzer power on/off. When the analyzer is energized,
the display shows the measured DOC or temperature value;
 the MODE button enables the DOC or temperature measuring mode, with
the display showing the measured DOC or temperature value and mg/dm3 or °С
character, respectively, coming on in the right half of the indicator;
 the CAL button selects the analyzer calibration mode. When pressed se-
quentially, the button causes the characters с0 (analyzer reset) and с1 (atmos-
pheric air calibration) to light up on the display;
 the ENTER button confirms the selected calibration mode and completes
calibration.
1.6 Measuring instruments, tools and accessories
1.6.1 The following tools and accessories, which are not included in the de-
livery set, will be additionally required for maintenance of the analyzer:
 2 mm cross screwdriver;
 В-1-250 beaker;
 КН-100-19/26 flask;
 hydroquinone, chemically pure;
 sodium or potassium hydroxide, chemically pure.

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2 INTENDED USE
2.1 Operating limitations
2.1.1 2.1.1 The MARK-302Т analyzer version is primarily used to measure
DOC in deaerated water.
2.1.2 2.1.2 Para.1.2.5 provides permissible concentrations for a number of
components which affect measuring results.
2.1.3 2.1.3 The analyzer should be positioned so as to prevent water from
getting on the converter unit.
2.1.4 2.1.4 When using the analyzer, avoid hitting or dropping the oxygen
sensor to keep its glass components intact.
2.2 Safety
2.2.1 The analyzer should only be operated by personnel who are familiar
with this manual and chemical handling safety rules in accordance with
GOST 12.1.007-76 and GOST 12.4.021-75.
2.2.2 The analyzer meets the requirements of Safety Class III to
GOST R 52319-2005. The rated supply voltage varies between 2,2 and 3,4 V. No
protective earthing is required.
2.2.3 By electromagnetic compatibility, the analyzer meets the requirements
of GOST R 51522-99 for Class B equipment.
2.3 Pre-starting procedures
On receipt of the analyzer, unpack it, check the set for completeness and
make sure that the packed components are intact.
If kept in cold conditions before delivery, the analyzer should be held at room
temperature for at least one hour before setting-up procedures.

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2.3.1 Power supply connection
To connect the power supply, remove the battery compartment cover located
on the rear panel of the converter unit. Install two AA-type alkaline batteries ob-
serving the polarity marking inside the battery compartment. Replace the battery
compartment cover.
With a power supply installed in the battery compartment, the analyzer can
indicate time, when turned off. The dot between hours and minutes flickers at an
interval of 1 second.
Time indication may be switched off and on again by pressing the MODE
button, with the analyzer off.
Proceed as follows to correct time:
 press the CAL button, minutes will start blinking on the display;
 use the MODE and ENTER buttons to set the minute value;
 press the CAL button, hours will start blinking on the display;
 use the MODE and ENTER buttons to set the hour value;
 press the CAL button to complete time setting, the analyzer goes into the
time indication mode.
Switch on the analyzer and check if the display shows DOC or temperature
readings in mg/dm3 or °С respectively.
IMPORTANT: ALWAYS OBSERVE polarity when installing batteries.
Failure to meet this condition may damage the analyzer!
When the display shows the sign, replace AA-type alkaline batteries.
2.3.2 Oxygen sensor setting-up procedures
Since the oxygen sensor from the analyzer set is delivered in the “dry” state,
it should be filled with electrolyte included with the delivery set, as described in pa-
ra.2.6.3, and submerged in distilled water for a minimum of 8 hours.
Make sure two AA-type alkaline batteries are installed in the converter unit.
Regardless of whether the analyzer is on or off, the sensor will receive polarizing
voltage needed to build up an electrode system.
2.3.3 Analyzer functional check
The analyzer functional check includes:

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 analyzer precalibration by atmospheric air oxygen;
 check of readings in the null solution.
It is recommended that the analyzer functional check be performed:
 after filling the sensor with electrolyte on delivery of the analyzer;
 after replacement of the membrane assembly or teflon film;
 if there are any doubts as to the analyzer’s serviceability.
2.3.3.1 Analyzer precalibration
Take the sensor out of the vessel with water and place it horizontally (put on
the table).
Press the MODE button to enable the DOC measuring mode in mg/dm3. The
analyzer display will show a figure measured in mg/dm3.
Keep the sensor in the air for 5 min.
Press the CAL button twice. The analyzer display will show the c1 symbol
showing the entry into the outside air calibration mode.
Press the ENTER button. The analyzer display will show DOC readings cor-
responding to the table of 100 % humidity air oxygen solubility for analyzer-
measured temperatures, with allowance for the atmospheric pressure at the time of
calibration, for example, c8.38 mg/dm3.
Wait at least 8 s before pressing the ENTER button once again. The donЕ
caption will appear shortly on the screen and the с symbol will go out. The analyzer
will go into the measuring mode, which means that precalibration is completed.
2.3.3.2 Reading check in the null solution
Prepare an oxygen-free (null) solution, and for this purpose:
 prepare an alkali solution (KOH or NaOH), concentration 5 g/dm3;
 pour it into a 0,3-0,5 dm3 vessel so that its level is 50 to 60 mm;
 add 0,3 to 0,5 g of hydroquinone and stir.
Uptime in air tight vessel is max 1 month.
Submerge the sensor, with its membrane down, in the solution and move it
to slightly agitate the solution in order to prevent air bubbles from amassing on the
membrane. The displayed analyzer reading should decrease slowly.
Take the analyzer readings in 30 min.
They should vary within ±3 mkg/dm3.

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With the above procedure successfully completed, the analyzer is ready for
normal service. The analyzer calibration by outside air shall then be performed as
per para.2.3.4.
If the readings do not decrease to the specified level, a sensor cycling opera-
tion should be carried out as per para.2.3.3.3.
2.3.3.3 Sensor cycling
Proceed as follows to carry out the cycling operation:
 switch on the analyzer;
 prepare a null solution as per para.2.3.3.2;
 submerge the sensor, with its membrane down, in the solution and move
it to slightly agitate the solution in order to prevent air bubbles from amassing on
the membrane;
 hold the sensor in the null solution for 5 min, then take it out, shake off the
solution drops from the membrane and hold it in the air for 5 min;
 repeat the null solution - air cycle 3 to 4 times;
 submerge the sensor in null solution again;
 take the analyzer reading in 30 min; it should be within ±3 mkg/dm3.
If the above steps fail to cause the analyzer readings in the null solution to
decrease to the desired values, this suggests either bad quality of the null solution
(bad reagents) or a fault in the analyzer (see section 2.6 Troubleshooting).
Calibration of the analyzer should then be performed subject to para.2.3.4 or
2.3.5.
If any error character (Е3, Е4, Е5, Е6, Е7, Е8, Е9) is displayed during the
analyzer functional check, also refer to section 2.6.
2.3.4 Analyzer calibration by outside air
Outside air calibration of the analyzer should be performed:
 when the device is new;
 once a shift (8 hr);
 after replacement of electrolyte, membrane and teflon film.
Calibration of the analyzer is performed in the outside air at temperatures be-
tween +15 °С and +35 °С and a 100 % relative humidity. It is more convenient to
perform calibration at room temperature.
Prior to calibration, the analyzer, with AA-type alkaline batteries installed,
should be held at room temperature for at least 1 hour. The analyzer may be left

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switched on. Submerge the sensor fully in distilled water of room temperature for a
minimum of 10 min.
Rinse the sensor in distilled water, shake off water drops from the sensor
membrane and put the sensor in the cone flask with a water layer 3 to 5 mm, as
shown in Fig.2.1. Position the flask at an angle of 30 to 45° to the horizontal for the
remaining water to flow off the membrane.
Fig. 2.1 − Position of the sensor inside the flask for analyzer calibration
Wait for 10 min before performing the outside air calibration steps which fol-
low.
1 Press the CAL button twice. The c1 character will appear on the display,
showing the entry into the outside air calibration mode.
2 Press the ENTER button. The analyzer will display DOC readings corre-
sponding to the table of 100 % humidity air oxygen solubility for analyzer-measured
temperature, with allowance for the atmospheric pressure at the time of calibration,
e.g. c8.38 mg/dm3.
3 Wait at least 8 s before pressing ENTER once again. The donЕ caption
will briefly appear on the display and the analyzer will go into the measuring mode.
It means the outside air calibration mode is completed and the analyzer is calibrat-
ed.
Once calibrated by outside air, the analyzer is ready for use.
Note: Outside air calibration of the analyzer may be cancelled before Step 3
by pressing MODE. The analyzer will go into the DOC measuring mode, retaining
the values of previous calibration coefficients.
2.3.5 Analyzer zero calibration
Analyzer zero calibration allows the sensor residual zero current to be com-
pensated within narrow limits (–3,0 to +3,0 mkg/dm3).
Sensor
Water
Flask

15
Proceeds as follows prior to carrying out this operation:
 switch on the analyzer;
 prepare a fresh null solution as per para.2.3.3.2;
 enable the DOC measuring mode in mg/dm3;
 perform cycling operations as per para.2.3.3.3;
 hold the sensor in the air for 5 min, submerge the sensor, with its mem-
brane down, in the null solution and move it to slightly agitate the solution in order
to prevent air bubbles from amassing on the membrane;
 hold the sensor in the null solution for at least 40 min.
Perform the following steps to set the analyzer zero.
1 Press CAL. The analyzer display will show the с0 caption.
2 Press ENTER. The analyzer display will show DOC Z0 readings in the null
solution without allowance for zero adjustment, e.g. с.002 mg/dm3.
3 Wait at least 8 s before pressing ENTER once again. The donЕ caption
will briefly appear on the display and the analyzer will go into the measuring mode.
The analyzer display will indicate a DOC value in the null solution after analyzer
zero setting:
 0,000; if −0,003 mg/dm3 ≤ Z0 ≤ 0.003 mg/dm3;
 Z0−0,003; if Z0 > 0,003 mg/dm3;
 Z0+0,003; if Z0 < −0,003 mg/dm3.
Note: Analyzer zero setting may be cancelled before Step 3, by pressing
MODE. The analyzer will go into the DOC measuring mode, retaining the values of
previous calibration coefficients.
2.4 Measurement procedure
2.4.1 Preparation for measurement using a flowing vat
The premesurement procedure as per Fig.2.2 includes the following steps:
 remove the hose from the flowing vat outlet connection;
 remove the protective bushing from the cable bushing by unscrewing it;
 screw in the flowing vat in place of the cable bushing.

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а b
Fig. 2.2
2.4.1.1 Measurement using a flowing vat
Connect the inlet connection of the flowing vat (with the sensor installed) to
the controlled water line with a flexible hose. Supply controlled water to the flowing
vat and position the vessel with sensor so that the sensor is nearly vertical, its
membrane down. Allow water to freely flow through the vessel for at least 10
minutes, until there are no air bubbles in the water flow. Nor should there be any
air bubbles on the sensor membrane. To remove bubbles from the membrane,
shake the vessel with sensor carefully.
Bubbles amassing in the hose bends, on the sensor membrane or in the wa-
ter line knee may substantially invalidate the results. One of the signs showing the
presence of air bubbles is that the analyzer oxygen readings will not settle, while
dropping slowly and continuously. Such a process caused by the air oxygen being
washed out from air bubbles may last 1-2 hours.
To eliminate air bubbles in the sampler line, it is recommended:
 to sharply increase (by 10-20 s) the water flow through the flowing vat;
 reduce the water flow to the normal level (400 to 800 cm3/min).
Switch on the analyzer and take the display readings.
Negative oxygen readings at sampler measurements suggest that the ana-
lyzed water contains some electroactive impurities.
Outlet
connection
Cable
bushing
Protective
bushing
Drainage
From sampler
Inlet
connection

17
Measurements may dispense with the flowing vat, if the sensor is placed in a
suitable vessel ensuring a controlled water flow of 5 cm/s in the sensor membrane
area. To protect the membrane from damage, it is recommended to screw in the
protective bushing.
Note: Subject to para.1.3.11, the MARK-302Т analyzer readout setting time
limit tу, when measuring DOC, is 30 min, i.e. after 30 min the analyzer readings in a
fresh null solution should be up to 0,003 mg/dm3.
The real readout setting time for newly released analyzers varies between 1
and 3 min.
When in use for a certain period, the analyzer may have an extended
readout setting time.
To determine the readout setting time of a specific analyzer, prepare a fresh
null solution, submerge the sensor in it, slightly agitating the solution with the sen-
sor, and record the time when the readings of 0,003 mg/dm3 are obtained. It is rec-
ommended to perform this operation once a month.
The 0,003 mg/dm3 reading recorded time may be used for measurement, i.e.
take reading when this time expires.
IMPORTANT: while operating the analyzer:
 keep the sensor membrane wet. The sensor should be kept in water dur-
ing intervals between measurements. There is a good reason to store the sensor
installed in the flowing vat filled with controlled water. To prevent water leakage,
the hoses of inlet and outlet connections may be connected with a short pipe;
 transport the oxygen sensor in the flowing vat filled with water, at positive
ambient temperatures;
 when brought into a warm room from the cold air, prior to enabling, hold
the analyzer at room temperature for at least 1 hour in order for condensed mois-
ture to evaporate.
2.4.2 Water temperature measurement
The temperature measurement mode t °С is enabled by pressing the MODE
button.
Allow for the analyzer readings to be set and record them as a measuring
result.

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2.4.3 Calculation of dissolved oxygen concentration by analyzer readings,
with allowance for the salt content
When measuring DOC in salty water, use the correction factor α, by which
the analyzer readings should be multiplied. The α value is defined with the formula:
 = 1−Сsalt  ε,
where Сsalt  salt content, g/dm3;
ε  factor listed in Table 2.1.
Table 2.1. − Correction factors
t °C ε t °C ε t °C ε t °C ε t °C ε
0,0 0,0063 11,0 0,0057 21,0 0,0052 31,0 0,0048 41,0 0,0043
1,0 0,0063 12,0 0,0057 22,0 0,0052 32,0 0,0047 42,0 0,0042
2,0 0,0062 13,0 0,0057 23,0 0,0051 33,0 0,0047 43,0 0,0042
3,0 0,0062 14,0 0,0055 24,0 0,0050 34,0 0,0046 44,0 0,0041
4,0 0,0060 15,0 0,0055 25,0 0,0050 35,0 0,0046 45,0 0,0041
5,0 0,0060 16,0 0,0055 26,0 0,0049 36,0 0,0045 46,0 0,0040
6,0 0,0060 17,0 0,0054 27,0 0,0049 37,0 0,0045 47,0 0,0040
7,0 0,0060 18,0 0,0054 28,0 0,0049 38,0 0,0044 48,0 0,0039
8,0 0,0058 19,0 0,0053 29,0 0,0048 39,0 0,0044 49,0 0,0039
9,0 0,0058 20,0 0,0053 30,0 0,0048 40,0 0,0043 50,0 0,0038
10,0
0,0058
Exemplary calculation of correction factor  :
Let Сsalt =10 g/dm3, t=20 °C,
thus ε =0,0053,
then  =1-10·0,0053=0,947.
Note: This method for salt content correction is based on the International
Standard ISO 5814 Water Quality – Determination Of Dissolved Oxygen – Electro-
chemical Probe Method.
2.5 Functional check
A serviceable analyzer should meet the following requirements:
 with the sensor placed in the null solution, the analyzer readings stay
within ± 3 mkg/dm3;

19
 when outside air calibration is accomplished, (para.2.3.4) neither Е3 nor
Е4 is displayed on the screen and readings Ccal, mg/dm3, are set with an accuracy
±1 % of the calculated value defined with the formula:
325.101
)(
2
atm
cal
Р
tСоС  ,
where Со2(t), mg/dm3  solubility of 100 % humidity air oxygen in distilled
water, at temperature t, °С, and normal atmospheric pressure of 101.325 кPa as
per Table A.1;
Рatm  atmospheric pressure as of the time of calibration, kPa.
2.6 Troubleshooting
2.6.1 The typical faults of the analyzer and remedial methods are summa-
rized in Table 2.2.
In case of troubles set out in Table 2.2, proceed as recommended in the
Remedy column, in accordance with the clauses given below and Fig.1.1 and 2.4.
Table 2.2
Trouble, symptoms Probable cause Remedy
1 With power on, no read-
ings are displayed
Poor battery contact Open the battery com-
partment and clean con-
tacts
Supply voltage below
acceptable level
Para.2.3.1 Replace bat-
teries
2 With power on, all or ran-
dom segments and charac-
ters illuminate on the
screen
Dead batteries Para.2.3.1. Replace bat-
teries
3 When the zero point of
measuring range is
checked, analyzer readings
go beyond ±0,003 mg/dm3
Ruptured or punctured
membrane, sensor seal
failure
Para.2.6.3, 2.6.4. Re-
place the membrane and
electrolyte
Moisture inside the
converter unit
Dry the converter unit for
3-4 days
Overstretched mem-
brane
Para.2.6.4. Replace the
membrane assembly
Bad null solution Replace the null solution
Broken (cracked) glass
holder of sensor elec-
trodes
Factory repair

20
Table 2.2 (Continue)
Trouble, symptoms Probable cause Remedy
4 When the analyzer is cal-
ibrated by outside air, Е3
(sensor current below rat-
ing) is displayed.
Electrolyte has leaked
out
Para.2.6.3. Fill in electro-
lyte
Contaminated mem-
brane
Para.2.6.2. Clean the
membrane
Dry membrane Keep the membrane in
water for 2-3 days with-
out dismantling the sen-
sor
Defective membrane Para.2.6.4. Replace the
membrane assembly
Analyzer sensor off the
outside air
Position the sensor in air
5 Electrolyte leaking out
fast
Ruptured membrane Para.2.6.4. Replace the
membrane assembly
6.1 Sharp change in and
increased instability of ana-
lyzer readings.
6.2 During analyzer calibra-
tion by outside air, Е4 (ex-
cess sensor current) is dis-
played on the screen.
Ruptured membrane Para.2.6.4. Replace the
membrane assembly
Contaminated electro-
lyte
Para.2.6.3. Replace
electrolyte
Moisture inside the
converter unit
Dry the converter unit for
3-4 days
Ruptured teflon film Para.2.6.4. Replace tef-
lon film
Analyzer sensor off the
outside air
Position the sensor in air
7 Extended time of re-
sponse to oxygen concen-
tration variations
Contaminated mem-
brane
Para.2.6.2. Clean the
membrane
Contaminated platinum
electrode
Para.2.6.5. Clean the
platinum electrode
8 During measurements,
Е5 (excess measured sen-
sor current) is displayed on
the screen. Analyzer does
not respond to pressed but-
tons, except button
Ruptured membrane Para.2.6.4. Replace the
membrane assembly
Contaminated electro-
lyte
Para.2.6.3. Replace
electrolyte
Moisture inside the
converter unit
Dry the converter unit for
3-4 days
Ruptured teflon film Para.2.6.4. Replace tef-
lon film
Broken down analyzer Factory repair