GREISINGER GOX 20 User manual

H43.0.01.6C-11
GHM Messtechnik GmbH • Standort Greisinger
Hans-Sachs-Str. 26 • D-93128 Regenstauf
+49 (0) 9402 / 9383-0 +49 (0) 9402 / 9383-33 [email protected]
Oxymeter
Measuring device for dissolved oxygen in liquids
Operating Manual GOX 20
WEEE-Reg.-Nr. DE93889386

H43.0.01.6C-11 Operating Manual GOX 20 Page 2 of 6
CONTENTS
1GENERAL NOTE....................................................................................................................................................2
2SAFETY...................................................................................................................................................................2
2.1 INTENDED USE ...................................................................................................................................................2
2.2 SAFETY SIGNS AND SYMBOLS ..............................................................................................................................2
2.3 SAFETY GUIDELINES............................................................................................................................................3
3PRODUCT SPECIFICATION..................................................................................................................................3
3.1 SCOPE OF SUPPLY..............................................................................................................................................3
3.2 OPERATION AND MAINTENANCE ADVICE................................................................................................................3
4OXYGEN MEASUREMENTS..................................................................................................................................4
5CALIBRATION IN AIR............................................................................................................................................4
6THE OXYGEN ELECTRODE..................................................................................................................................5
7SPECIFICATION.....................................................................................................................................................6
8RESHIPMENT AND DISPOSAL.............................................................................................................................6
8.1 RESHIPMENT......................................................................................................................................................6
8.2 DISPOSAL INSTRUCTIONS....................................................................................................................................6
1 General Note
Read this document carefully and get used to the operation of the device before you use it. Keep this document
within easy reach near the device for consulting in case of doubt.
Mounting, start-up, operating, maintenance and removing from operation must be done by qualified, specially trained
staff that have carefully read and understood this manual before starting any work.
The manufacturer will assume no liability or warranty in case of usage for other purpose than the intended one, ig-
noring this manual, operating by unqualified staff as well as unauthorized modifications to the device.
The manufacturer is not liable for any costs or damages incurred at the user or third parties because of the usage or
application of this device, in particular in case of improper use of the device, misuse or malfunction of the connection
or of the device.
The manufacturer is not liable for misprints..
2 Safety
2.1 Intended Use
The safety requirements (see below) have to be observed.
The device must be used only according to its intended purpose and under suitable conditions.
Use the device carefully and according to its technical data (do not throw it, strike it, …)
Protect the device from dirt.
2.2 Safety signs and symbols
Warnings are labelled in this document with the followings signs:
DANGER
Caution! This symbol warns of imminent danger, death, serious injuries and
significant damage to property at non-observance.

Attention! This symbol warns of possible dangers or dangerous situations
which can provoke damage to the device or environment at non-
observance.
Note! This symbol point out processes which can indirectly influence opera-
tion or provoke unforeseen reactions at non-observance.

H43.0.01.6C-11 Operating Manual GOX 20 Page 3 of 6
2.3 Safety guidelines
This device has been designed and tested in accordance with the safety regulations for electronic devices.
However, its trouble-free operation and reliability cannot be guaranteed unless the standard safety measures and
special safety advises given in this manual will be adhered to when using the device.
1. Trouble-free operation and reliability of the device can only be guaranteed if the device is not subjected to any
other climatic conditions than those stated under "Specification".
If the device is transported from a cold to a warm environment condensation may cause in a failure of the func-
tion. In such a case make sure the device temperature has adjusted to the ambient temperature before trying a
new start-up.
2. If there is a risk whatsoever involved in running it, the device has to be switched off immediately
and to be marked accordingly to avoid re-starting.
Operator safety may be a risk if:
- there is visible damage to the device
- the device is not working as specified
- the device has been stored under unsuitable conditions for a longer time.
In case of doubt, please return device to manufacturer for repair or maintenance.
3. When connecting the device to other devices the connection has to be designed most thoroughly as internal
connections in third-party devices (e.g. connection GND with protective earth) may lead to undesired voltage po-
tentials that can lead to malfunctions or destroying of the device and the connected devices.
4. Do not use these products as safety or emergency stop devices or in any other application where
failure of the product could result in personal injury or material damage.
Failure to comply with these instructions could result in death or serious injury and material dam-
age.
5. Caution, acid! The electrode contains KOH. KOH can cause severe chemical burns! If leaking,
avoid contact.
If there was contact:
- to skin: flush contacted area with large amounts of water for several minutes.
- to clothing: remove contaminated clothing.
- to eyes: flush with large amounts of water for several minutes, obtain medical treatment.
After swallowing:
- give large volumes of water. DO NOT induce vomiting!
- obtain medical treatment.
3 Product Specification
3.1 Scope of supply
The scope of supply includes:
Device, incl. 9V-battery block
Operating Manual
3.2 Operation and maintenance advice
•Battery operation:
If ‘bAt’ is shown in the lower display the battery has been used up and needs to be replaced. However, the device
will operate correctly for a certain time. If ‘bAt’ is shown in the upper display the voltage is too low to operate the
device; the battery has been completely used up.
The battery has to be taken out, when storing device above 50 °C.
We recommend taking out battery if device is not used for a longer period of time.
•For measuring remove the protective flask of the electrode.
•Please note: the electrode measurement is sensitive against shocks!
By stirring of the electrode in the measured liquid be careful that the electrode does not hit the container. A vibra-
tion of the electrode has a effect to the measured value.
•Store the oxygen electrode always in water, either in the protective flask, or directly in a vessel filled with dechlo-
rinated water. For storage in the protective flask first push the cap oh the electrode second the o-ring and thereaf-
ter put the electrode in the flask and screw the cap down the flask.
Note: for measuring remove the protective flask!
If the diaphragm has dried up the electrode must be soaked in water for approx. 2 h prior to measuring start-up.
Then a calibration can be carried out without any problems.
_DANGER
_DANGER

H43.0.01.6C-11 Operating Manual GOX 20 Page 4 of 6
4 Oxygen measurements
Please observe the following rules when measuring dissolved oxygen:
- As it is subject to an ageing process the electrode needs to be calibrated at regular intervals. To do so the elec-
trode has to be adjusted according to the oxygen content of the atmospheric air. We recommend that a calibra-
tion is carried out before a new measuring series is started.
- The electrode temperature has to be identical to those of the liquid to be measured. This can be checked as fol-
lows:
Switch device to temperature display mode and stirr electrode in water till the temperature display shows
a steady measuring value.
- To obtain accurate oxygen measuring results the electrode needs to be stirred with at least 30cm/s.
A sufficient flow speed is achieved by moving the electrode by hand or by means of a stirring hardware. The
minimum required flow speed is achieved when an even quicker movement of the electrode does not result in an
increased value being displayed.
How to carry out measurements:
1. Switch on device and set to temperature display.
2. Place electrode in object to be measured and wait for the temperature display to become steady.
3. Switch over device to oxygen measuring. Generate flow speed required by stirring. Read-off measuring value as
soon as it is steady.
5 Calibration in air
Each device has been tested and calibrated in our works.
As mentioned above the oxygen electrode is subject to ageing; we, therefore, recommend to check calibration prior
to starting a new measuring series:
-Clean membrane with a soft cloth. Put electrode on table wrapped in Kleenex or a towel to protect it from
draughts.
-Switch over to temperature measurements and wait for the electrode to adopt the ambient temperature (approx.
15 minutes). Make sure that electrode is not subjected to any external heat sources (e.g. lamp etc).
-As soon as the temperature is steady, switch over device to oxygen measuring and compare the oxygen con-
centration shown with the values given in the table below.
If the value displayed on the GOX 20 differs from the one given in the table, it may be adjusted by means of the
„slope-knob“.
If it can no longer be adapted to the values given, the oxygen electrode needs maintenance or is used up and needs
to be replaced.
GOX 20 can also be calibrated in water. We, nevertheless, recommend air calibration as, without additional equip-
ment, it is quite difficult to determine if the water used for calibration is oxygen saturated or not.
Air temp.
O2-value
Air temp.
O2-value
Air temp.
O2-value
( °C )
( mg/l )
( ° C )
( mg/l )
( °C )
( mg/l)
0
14,1
11
11,1
22
9,1
1
13,8
12
10,9
23
9,0
2
13,5
13
10,7
24
8,9
3
13,2
14
10,5
25
8,7
4
12,9
15
10,3
26
8,6
5
12,6
16
10,1
27
8,5
6
12,3
17
9,9
28
8,3
7
12,1
18
9,8
29
8,2
8
11,8
19
9,6
30
8,1
9
11,6
20
9,4
31
8,0
10
11,3
21
9,3
32
7,9

H43.0.01.6C-11 Operating Manual GOX 20 Page 5 of 6
6 The oxygen electrode
The oxygen electrode is an active electrode consisting of a silver cathode and a
lead anode using potassium hydroxide (KOH) as an electrolyte. In case of oxygen
being present it will be reduced at the silver cathode and the electrode produces
electric current. In case of no oxygen being present not current will be produced.
Both the silver cathode and the lead anode will be used up during oxygen measur-
ing. The electrode ages. We, therefore, recommend regular maintenance of the
electrode at monthly intervals (p.r.t. ‘Electrode maintenance’).
When is electrode maintenance required:
•Unless it is used the electrode is to be stored in the protective flask filled with
water or directly in a vessel filled with dechlorinated water.
•Residues of bacteria, fungi or algae must be removed prior to measuring using a
soft paper towel.
•If a calibration can no longer be carried out or if the membrane is damaged the
electrode needs maintenance.
•In the course of the time air bubbles may accumulated underneath the mem-
brane. As long as they are small and do not affect the silver cathode the meas-
urements will not be influenced. If, however, there is a large ring of air bubbles
underneath the membrane covering the silver cathode, the electrode needs
maintenance.
Safety advice:
! Attention during maintenance is required as the electrolyte is highly
corrosive!
Use disposable gloves during maintenance, if available, or rinse hands thoroughly
with water.
Electrode maintenance:
1. Prepare liquid absorbing paper towel.
2. Remove membrane cap and wipe off electrolyte solution with paper cloth.
3. Clean silver cathode using sand paper (grain size 240). Do not shine silver cathode as its surface needs to be
rough so that the electrolyte can be dispersed evenly. Remove any dust from grinding.
4. Take out replenishing screw and top up with electrolyte till it is spilling out (e.g. using a disposable syringe). Put
back replenishing screw.
5. Put new membrane cap on the paper towel and fill up with electrolyte making sure there are no air bubbles.
6. Put electrode into cap vertically from above till the thread catches. Then take up cap with paper towel and screw
onto electrode from underneath. Electrolyte will be displaced from the membrane head, flowing over.
7. Mop up excess electrolyte using paper towel.
8. Turn electrode around and check for air bubbles. If there are no air bubbles or only tiny ones the maintenance
has been completed. If there are large air bubbles the process has to be repeated.
If O-ring has been damaged, it has to be replaced.
Please note: Prior to its being calibrated again the electrode needs to be lying on a table for at least 3 hours.
If electrode can no longer be calibrated although it has been properly maintained, the electrode needs to be returned
to manufacturer for check up and may have to be replaced.
Replenishing hole
Electrode shaft
O-ring
Membrane cap

H43.0.01.6C-11 Operating Manual GOX 20 Page 6 of 6
7 Specification
Measuring range
Oxygen 0.0 ... 20.0 mg/l O2
Temperature 0.0 ... 40.0 °C
Resolution
Oxygen 0.1 mg/l O2
Temperature 0.1 °C
Accuracy (at nominal temperature) ±1digit)
Oxygen ± 2 % of meas. value ± 0.2 mg/l
Temperature ± 0.3 °C (ranging from 0-30°C)
Electrode: active type. electrode dia front: approx. 12mm, length: approx. 220mm (incl. anti-
buckling protection), cable, approx. 2m long, permanently connected to measuring de-
vice
Response time: 95% in 10sec., depending on temperature.
Service life: 3 years or more depending on proper maintenance
Operating pressure: max. 3 bar.
Temperature compensation : automatically via temperature sensor integrated in electrode.
Calibration: electrode may be calibrated quite simply in atmospheric air.
Display: 3½-digit, 13mm high LCD-display
Nominal temperature: 25°C
Operating conditions: 0 to 50°C, 0 to 95%RH (non condensing)
Storage temperature: -20 to 70°C
Power supply: 9 V-battery, type IEC 6F22 (included)
Power consumption: max. 1mA
Low battery warning: „BAT“ will be displayed automatically at the left hand corner of the display as soon
as battery is low .
Dimensions: 106 x 69 x 30 mm. shock-resistant ABS housing.
Weight: approx. 250 g (cpl. with battery and probe)
EMC: The device corresponds to the essential protection ratings established in the Regu-
lations of the Council for the Approximation of Legislation for the member countries
regarding electromagnetic compatibility (2004/108/EG)
additional fault: <1%
8 Reshipment and Disposal
8.1 Reshipment
All devices returned to the manufacturer have to be free of any residual of measuring media and other
hazardous substances. Measuring residuals at housing or sensor may be a risk for persons or envi-
ronment
Use an adequate transport package for reshipment, especially for fully functional devices. Please
make sure that the device is protected in the package by enough packing materials.
8.2 Disposal instructions
Batteries must not be disposed in the regular domestic waste but at the designated collecting points.
The device must not be disposed in the unsorted municipal waste! Send the device directly to us (suffi-
ciently stamped), if it should be disposed. We will dispose the device appropriate and environmentally
sound.
_DANGER