АЯ 74
MARK-302Т
DISSOLVED
OXYGEN
METER
Operation Manual
Nizhny Novgorod
2010
2
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 (831) 229-65-67, 412-29-40
E-mail: market@vzor.nnov.ru
Website: www.vzornn.com
3
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
4
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 accordance 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).
5
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.
6
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/dm
ment at an analyte temperature of (20,0±0,2) °С and ambient temperature of
(20±5) °С, mg/dm3 ……………………………….…........................... ±(0,003+0,04С),
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.
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).
an analyte temperature coinciding with the calibration temperature which varies between +15 °С and +35 °С, at an ambient temperature of (20±5) °С,
mg/dm3……….…………………………………………...................... ± (0,003+0,04C).
ature measurement at an ambient temperature of (20±5) °С, °C ….……...…... ±0,3.
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.
DOC measurement, min …………..……….…………………………….…………… 2.
time tу in DOC measurement, min ……….…………......................…………..…… 30.
in analyte temperature measurement, min ……………………….………….………. 1.
analyte temperature measurement, min ………………………………………….….. 3.
17,45 15,29 13,48 12,10 10,00 9,85 8,98 8,30 7,69 7,12 6,59
3
1.3.2 Limits of the analyzer allowable basic absolute error in DOC measure-
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
1.3.4 Limits of the analyzer allowable additional absolute error in DOC
1.3.5 Limits of the analyzer allowable absolute error in DOC measurement at
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-
1.3.8 Limits of the analyzer allowable basic absolute error in analyte temper-
1.3.9 Limit of the permissible value of the analyzer readout setting time t
0.9
in
1.3.10 1.3.10 Limit of the permissible value of the analyzer readout setting
1.3.11 Limit of the permissible value of the analyzer readout setting time t
0.9
1.3.12 Limit of the permissible value of the analyzer readout setting time tу in
7
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 impenetrable for liquid and water vapor. From the analyte, oxygen diffuses through
the membrane into a thin layer of electrolyte between the electrodes and the membrane 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
8
1
3
2
4
5 12
11
13
8
7
16
6
MODE CAL ENTER
DOC in the analyte.
The analyzer features a temperature sensor (platinum thermal resistor) to
measure temperature and to automatically compensate for the temperature dependence 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 signals 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 sensor 2.
а b
17
14
15
10
9
Fig. 1.1
9
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 membrane 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 (atmospheric 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.
10
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.
11
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 observing 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 para.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:
12
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 corresponding to the table of 100 % humidity air oxygen solubility for analyzermeasured 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/dm
pour it into a 0,3-0,5 dm
3
vessel so that its level is 50 to 60 mm;
3
;
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.
13
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 operation 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 between +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
14
Flask
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.
Sensor
Water
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 follow.
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 corresponding 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 calibrated.
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 compensated within narrow limits (–3,0 to +3,0 mkg/dm3).
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/dm
Z
−0,003; if Z0 > 0,003 mg/dm3;
0
Z
+0,003; if Z0 < −0,003 mg/dm3.
0
3
≤ 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.
16
Cable
bushing
Outlet
connection
Protective
bushing
Drainage
connection
Inlet
From sampler
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 water 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 analyzed water contains some electroactive impurities.
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 sensor, and record the time when the readings of 0,003 mg/dm3 are obtained. It is recommended 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 during 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 moisture 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.
18
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−С
salt
ε,
where С
salt content, g/dm3;
salt
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
1,0
2,0
3,0
4,0
5,0
6,0
7,0
8,0
9,0
10,0
0,0063
0,0063
0,0062
0,0062
0,0060
0,0060
0,0060
0,0060
0,0058
0,0058
0,0058
11,0
12,0
13,0
14,0
15,0
16,0
17,0
18,0
19,0
20,0
0,0057
0,0057
0,0057
0,0055
0,0055
0,0055
0,0054
0,0054
0,0053
0,0053
21,0
22,0
23,0
24,0
25,0
26,0
27,0
28,0
29,0
30,0
0,0052
0,0052
0,0051
0,0050
0,0050
0,0049
0,0049
0,0049
0,0048
0,0048
31,0
32,0
33,0
34,0
35,0
36,0
37,0
38,0
39,0
40,0
0,0048
0,0047
0,0047
0,0046
0,0046
0,0045
0,0045
0,0044
0,0044
0,0043
41,0
42,0
43,0
44,0
45,0
46,0
47,0
48,0
49,0
50,0
0,0043
0,0042
0,0042
0,0041
0,0041
0,0040
0,0040
0,0039
0,0039
0,0038
Exemplary calculation of correction factor :
Let С
=10 g/dm3, t=20 °C,
salt
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 – Electrochemical 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 C
, mg/dm3, are set with an accuracy
cal
±1 % of the calculated value defined with the formula:
Р
cal
)(
tСоС ,
2
atm
325.101
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;
Р
atmospheric pressure as of the time of calibration, kPa.
atm
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.
Trouble, symptoms Probable cause Remedy
1 With power on, no readings are displayed
2 With power on, all or random segments and characters illuminate on the
screen
3 When the zero point of
measuring range is
checked, analyzer readings
go beyond ±0,003 mg/dm
Poor battery contact Open the battery com-
partment and clean con-
tacts
Supply voltage below
acceptable level
Para.2.3.1 Replace bat-
teries
Dead batteries Para.2.3.1. Replace bat-
teries
Ruptured or punctured
membrane, sensor seal
failure
3
Moisture inside the
converter unit
Overstretched membrane
Para.2.6.3, 2.6.4. Re-
place the membrane and
electrolyte
Dry the converter unit for
3-4 days
Para.2.6.4. Replace the
membrane assembly
Bad null solution Replace the null solution
Broken (cracked) glass
Factory repair
holder of sensor electrodes
Table 2.2
20
Table 2.2 (Continue)
Trouble, symptoms Probable cause Remedy
4 When the analyzer is calibrated by outside air, Е3
(sensor current below rating) is displayed.
5 Electrolyte leaking out
fast
6.1 Sharp change in and
increased instability of analyzer readings.
6.2 During analyzer calibration by outside air, Е4 (excess sensor current) is displayed on the screen.
7 Extended time of response to oxygen concentration variations
8 During measurements,
Е5 (excess measured sensor current) is displayed on
the screen. Analyzer does
not respond to pressed buttons, except button
Electrolyte has leaked
out
Contaminated membrane
Para.2.6.3. Fill in electro-
lyte
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
Position the sensor in air
outside air
Ruptured membrane Para.2.6.4. Replace the
membrane assembly
Ruptured membrane Para.2.6.4. Replace the
membrane assembly
Contaminated electrolyte
Moisture inside the
converter unit
Para.2.6.3. Replace
electrolyte
Dry the converter unit for
3-4 days
Ruptured teflon film Para.2.6.4. Replace tef-
lon film
Analyzer sensor off the
Position the sensor in air
outside air
Contaminated membrane
Contaminated platinum
electrode
Para.2.6.2. Clean the
membrane
Para.2.6.5. Clean the
platinum electrode
Ruptured membrane Para.2.6.4. Replace the
membrane assembly
Contaminated electrolyte
Moisture inside the
converter unit
Para.2.6.3. Replace
electrolyte
Dry the converter unit for
3-4 days
Ruptured teflon film Para.2.6.4. Replace tef-
lon film
Broken down analyzer Factory repair
21
Е
9
Тable 2.2 (Continue)
Trouble, symptoms Probable cause Remedy
9 During measurements,
indication of exceeded display digit capacity appears
on the screen:
Operator’s errors in analyzer calibrations
Para.2.6.6. Perform op-
erations to set initial ana-
lyzer parameters
Broken down analyzer Factory repair
“Е6 mg/dm3” readings
less than 199,9 mg/dm3;
“Е7 mg/dm3” − readings
exceeding 199,9 mg/dm3.
10 During measurements,
Е8 is displayed on the
screen.
11
is displayed on the
screen.
12 Sharp change in and
increased instability of analyzer readings during flow-
Faulty temperature
measuring channel
(heat probe breakage)
Writing error in
ЕЕРRОМ memory
High rate of flow
through the flowing vat
Factory repair
Factory repair
Set the rate of flow
through the flowing vat at
400 to 800 cm3/min
ing vat measurements.
2.6.2 Membrane cleaning
The sensor membrane may be cleaned with a wad of alcohol-soaked cotton.
The sensor membrane may also be submerged in a weak solution (2 %) of
sulfuric acid for about 1 hour, and then wash it in running water.
2.6.3 Filling the sensor with electrolyte, electrolyte replacement
As it is supplied in a dry state (without electrolyte), the sensor needs to be
filled with electrolyte after its receipt from the manufacturer.
Unscrew and remove the protective bushing from the sensor as per Fig.2.3.
Remove the membrane assembly from the bushing. Draw electrolyte from
SPK into a syringe. Take the membrane assembly and, holding it with the membrane down, inject electrolyte to fill two thirds of the volume, taking care to avoid
damaging the membrane. While continuing to keep vertical the membrane assembly filled with electrolyte, set it on the bushing against the stop. Screw in the protective bushing.
22
Cable bushing
Case
Syringe
filled with
electrolyte
Bushing
Capron thread
Teflon film
Membrane assembly
Membrane
Remove
Protective bushing
Remove
Fig. 2.3 − Dismantling the sensor for filling and replacement of electrolyte,
replacement of teflon film and membrane assembly
IMPORTANT: The membrane should be stretched and pressed firmly
against the sensor platinum cathode. The membrane SHALL NEVER separate
from the cathode!
After a certain period of service, the sensor may have the volume of electrolyte reducing due to leakage through pinholes or ruptures in the membrane, which
necessitates electrolyte replacement.
23
Remove the membrane assembly from bushing 6, drain the remaining electrolyte and wash the assembly with distilled water. Fill the membrane assembly
with new electrolyte.
Electrolyte composition: KCl, chemically pure – 14 g; KOH, chemically pure –
0.2 g; versene – 0.15 g; distilled water – up to 0.1 dm3. Filter the solution.
2.6.4 Replacement of the membrane assembly and teflon film
2.6.4.1 Replacement of the membrane assembly may be necessary in case
of mechanical damage (cracks, ruptures) or overstretching of the membrane. A
faulty membrane manifests itself in analyzer reading instability, high analyzer readings in the null solution and longer time of response during DOC measurement.
Unscrew and remove the protective bushing from the sensor as per Fig.2.3.
Remove the membrane assembly form the inner case and drain the electrolyte.
Check the teflon film for damage.
The film should be firmly pressed against the cathode, in a wrinkle-free man-
ner. Damaged film should be replaced.
Once the teflon film is removed, check the sensor electrode to see if they
look as follows:
platinum cathode 1 (Fig.1.1b) sealed in a glass tube should be clean;
silver anode 2, coiled over the tube should be gray.
If necessary, clean the electrodes with a wad of alcohol-soaked cotton.
IMPORTANT: NEVER use any abrasive for cleaning electrodes!
2.6.4.2 Damaged teflon film should be replaced with new one from spare
parts kit. To do this, place it on the cathode, press the film edges firmly against the
side surface of the glass tube and, holding the edges by hand, wind around 5 to 6
laps of caprone thread making 2 to 3 knots. Cut off with scissors surpluses of teflon
film not closer than 3-5 mm from caprone.
IMPORTANT: NO rupture or hole in teflon film in the platinum cathode
area are permissible!
Take a new membrane assembly from SPK and, holding the assembly vertically, fill electrolyte with it. Then carefully fit the assembly with electrolyte over the
bushing and place the protective bushing.
After membrane assembly/teflon film replacement, perform the steps detailed in para.2.3.3 and 2.3.4.
24
2.6.5 Platinum electrode cleaning
A need for platinum electrode cleaning in a special solution arises in
6-12 months after the first use. It is not recommended to clean the electrode before
this period expires.
To clean the electrode, prepare two solutions.
Solution composition:
Solution1: chlorohydric acid (concentrated) − 50 cm3,
distilled water up to 100 cm3;
Solution 2: acetic acid (80 to 100 %).
Pour the solutions into vessels making sure that the liquid level is up to
3 mm. Then proceed as follows:
remove the teflon film;
wash the sensor with distilled water;
place the sensor into a vessel with Solution 1 and hold it there for 1 hour;
wash the sensor with distilled water;
place the sensor into a vessel with Solution 2 and hold it there also for 1
hour;
IMPORTANT: NEVER PLACE the silver anode in the above solutions!
wash the sensor with distilled water.
Then proceed to para.2.6.4.2.
Note: After cleaning the platinum electrode and performing the steps as per
para.2.6.4.2 and 2.3.3, 2.3.4, the analyzer, when placed in the null solution, can
display low negative values over a period from 24 to 48 hours. For the analyzer to
resume its normal operation as soon as possible, replace the electrolyte after
24 hours.
2.6.6 Analyzer initial parameter setting
The instrument features a mode for setting the analyzer initial parameters of
shift (zero shift) and steepness corresponding to the averaged sensor. This mode
enables calibration to be always performed from the fixed initial conditions.
Use this mode when in doubt as to whether the analyzer has operated cor-
rectly in performing calibration modes.
25
2.6.6.1 Zero shift setting
1 Switch off the analyzer.
2 Press the CAL button and, keeping it pressed, switch on the analyzer. Af-
ter a sound signal release the CAL button. The screen will display с2.
3 Press the ENTER button. The donЕ capture will briefly appear on the
screen and the analyzer will go into the measurement mode. The display will indicate readings in mg/dm3 with zero shift.
2.6.6.2 Average steepness setting
1 Switch off the analyzer.
2 Press the CAL button and keeping it pressed, switch on the analyzer. Af-
ter a sound signal release the CAL button. The screen will display с2. Press the
CAL button again. The screen will display с3.
3 Press the ENTER button. The donЕ capture will briefly appear on the
screen and the analyzer will go into the measurement mode. The display will indicate readings in mg/dm3 corresponding to the average sensor steepness.
Once the analyzer initial parameters are set, proceed to para.2.3.4.
26
3 MAINTENANCE
Maintenance of the analyzer comprises:
analyzer calibration by outside air (para.2.3.4) to be carried out every 8
hours;
analyzer zero calibration (para.2.3.5) to be carried out every three
months;
sensor cycling (para.2.3.3.3) to be carried out when the analyzer has not
been in use for more than 24 hours. This operation ensures the highest response
rate of the instrument in DOC measurements.
When the conditions described in para.2.5 are fulfilled, the analyzer meets
the specifications listed in para.1.3.
4 DELIVERY SET
4.1 The delivery set is shown in Table 4.1.
Table 4.1
Description Quantity
1 MARK-302Т dissolved oxygen analyzer
(with sensor, cable length 2 m)
2 Flowing vat 1
3 Spare parts kit (to oxygen sensor) 1
4 Tool and accessory kit 1
5 Tool and accessory kit 1
6 Operation Manual 1
1
27
APPENDIX A
(reference)
Solubility of 100 % humidity air oxygen in distilled water, depending on the
temperature
Р
=101,325 кPa
atm
Table A.1 mg/dm
t, °С 0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9
0 14,62 14,58 14,54 14,50 14,46 14,42 14,38 14,34 14,30 14,26
1 14,22 14,18 14,14 14,10 14,06 14,02 13,98 13,94 13,90 13,87
2 13,83 13,79 13,75 13,72 13,68 13,64 13,60 13,57 13,53 13,49
3 13,46 13,42 13,39 13,35 13,32 13,28 13,24 13,21 13,17 13,14
4 13,11 13,07 13,04 13,00 12,97 12,93 12,90 12,87 12,83 12,80
5 12,77 12,74 12,70 12,67 12,64 12,61 12,57 12,54 12,51 12,48
6 12,45 12,41 12,38 12,35 12,32 12,29 12,26 12,23 12,20 12,17
7 12,14 12,11 12,08 12,05 12,02 11,99 11,96 11,93 11,90 11,87
8 11,84 11,81 11,79 11,76 11,73 11,70 11,67 11,64 11,62 11,59
9 11,56 11,53 11,51 11,48 11,45 11,42 11,40 11,37 11,34 11,32
10 11,29 11,26 11,24 11,21 11,18 11,16 11,13 11,11 11,08 11,06
11 11,03 11,00 10,98 10,95 10,93 10,90 10,88 10,85 10,83 10,81
12 10,78 10,76 10,73 10,71 10,68 10,66 10,64 10,61 10,59 10,56
13 10,54 10,52 10,49 10,47 10,45 10,42 10,40 10,38 10,36 10,33
14 10,31 10,29 10,27 10,24 10,22 10,20 10,18 10,15 10,13 10,11
15 10,08 10,06 10,04 10,02 10,00
16 9,87
17 9,66
18 9,47
19 9,28
20 9,09
21 8,91
22 8,74
23 8,58
24 8,42
25 8,26
26 8,11
27 7,97
28 7,83
29 7,69
30 7,56
31 7,44
32 7,33
33 7,22
34 7,10
35 6,99
36 6,82
37 6,71
38 6,61
39 6,51
9,85
9,64
9,45
9,26
9,08
8,89
8,73
8,56
8,40
8,25
8,10
7,95
7,81
7,67
7,54
7,44
7,32
7,21
7,09
6,98
6,81
6,70
6,60
6,50
9,83
9,62
9,43
9,24
9,06
8,87
8,71
8,55
8,39
8,23
8,08
7,94
7,80
7,66
7,53
7,43
7,31
7,19
7,08
6,97
6,80
6,69
6,59
6,49
9,81
9,60
9,41
9,22
9,04
8,86
8,69
8,53
8,37
8,22
8,07
7,92
7,78
7,65
7,52
7,42
7,30
7,18
7,07
6,96
6,78
6,68
6,58
6,48
9,79
9,58
9,39
9,21
9,02
8,85
8,68
8,51
8,36
8,20
8,05
7,91
7,77
7,63
7,50
7,41
7,29
7,17
7,06
6,95
6,77
6,67
6,57
6,47
9,98
9,77
9,56
9,37
9,19
8,01
8,83
8,66
8,50
8,34
8,19
8,04
7,89
7,76
7,62
7,49
7,39
7,28
7,16
7,05
6,94
6,76
6,66
6,56
6,46
9,96
9,75
9,54
9,36
9,17
8,99
8,81
8,64
8,48
8,32
8,17
8,02
7,88
7,74
7,61
7,48
7,38
7,26
7,15
7,04
6,93
6,75
6,65
6,55
6,45
9,94
9,73
9,52
9,34
9,15
8,97
8,80
8,63
8,47
8,31
8,16
8,01
7,87
7,73
7,59
7,46
7,37
7,25
7,14
7,03
6,92
6,74
6,64
6,54
6,44
9,92
9,71
9,50
9,32
9,13
8,95
8,78
8,61
8,45
8,29
8,14
7,99
7,85
7,71
7,58
7,45
7,36
7,24
7,13
7,01
6,90
6,73
6,63
6,53
6,43
9,90
9,69
9,49
9,30
9,11
8,93
8,76
8,60
8,43
8,28
8,13
7,98
7,84
7,70
7,57
7,44
7,35
7,23
7,11
7,00
6,89
6,72
6,62
6,52
6,42
3
28
Table A.1 (Continue) mg/dm3
t, °С 0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9
40 6,41
41 6,31
42 6,21
43 6,12
44 6,03
45 5,93
46 5,84
47 5,75
48 5,66
49 5,58
50 5,49
6,40
6,30
6,20
6,11
6,02
5,92
5,83
5,74
5,66
5,57
5,48
6,39
6,29
6,19
6,10
6,01
5,92
5,82
5,74
5,65
5,56
5,47
6,38
6,28
6,19
6,09
6,00
5,91
5,82
5,73
5,64
5,55
5,47
6,37
6,27
6,18
6,08
5,99
5,90
5,81
5,72
5,63
5,54
5,46
6,36
6,26
6,17
6,07
5,98
5,89
5,80
5,71
5,62
5,53
5,45
6,35
6,25
6,16
6,06
5,97
5,88
5,79
5,70
5,61
5,52
5,44
6,34
6,24
6,15
6,05
5,96
5,87
5,78
5,69
5,60
5,52
5,44
6,33
6,23
6,14
6,04
5,95
5,86
5,77
5,68
5,59
5,51
5,43
6,32
6,22
6,13
6,04
5,94
5,85
5,76
5,67
5,59
5,50
5,42
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