Ele 521-050 User manual

Dissolved Oxygen Meter
521-050
1 9907X0046 Issue 1
OPERATING INSTRUCTIONS
Dissolved Oxygen Meter
521-050
ELE International
Chartmoor Road, Chartwell Business
Park
Leighton Buzzard, Bedfordshire, LU7
4WG England
phone: [phone]
fax: [phone]
email: [email protected]
http://www.ele.com
ELE International, a division of Hach Lange Ltd.
Distributor:
ELE International
Soiltest Product Division
PO Box 389, Loveland, CO 80539
USA
phone: [phone]
fax: [phone]
email: [e-mail]
http://www.eleusa.com
In the interests of improving and updating its equipment, ELE reserves the right to alter
specifications to equipment at any time ELE International 2006 ©

Dissolved Oxygen Meter
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Contents
Section Page
1 Introduction 3
2 Specification 3
3 Installation 3
4 Displays 4
5 Controls 5
6 Preparation for Use 5
7 Operation 6
8 Calibration 6
9 Performing Measurements 8
10 Data Storage 8
11 Good Practice Guidelines 9
12 Maintenance 10
13 Troubleshooting Guide 11
14 Battery Replacement 13
15 Auto Shut Off 13
16 Health & Safety 13
17 EC Declaration of Conformity 14
WEEE Directive

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1 Introduction
The 521-050 is a general purpose, hand held Dissolved Oxygen Meter
allowing accurate measurement with ease of use. The custom liquid crystal
display simultaneously shows percentage dissolved oxygen or oxygen
concentration (mg/l) and temperature. The dissolved oxygen reading is
automatically corrected for temperature. Corrections for pressure and salinity
can be entered manually. The instrument is housed in a robust,
ergonomically designed case. An indication of battery life is also
permanently shown on the display. An automatic switch off facility helps to
conserve battery life.
2 Specification
DO2Ranges:
-5 to 199%
-5 to 25.0%
-5 to 19.99 mg/l
Resolution:
1% / 0.1% / 0.01 mg/l
Accuracy:
±2% within 10°C of calibration temperature
Temperature Ranges:
-10 to +105°C / 14 to 220°F
Resolution:
0.1°C / 1°F
Accuracy:
±0.5°C / ±1°F
ATC Range:
0 to +60°C / 32 to 140°F
Power:
2 AA cells
Size:
175(l)x75(w)x35(d)mm
Weight:
250g
3 Installation
Unpack the instrument and ensure the following items are present:
A. DO2Meter
B. DO2/Temperature Probe
C. 2 x AA alkaline batteries (fitted)
D. Membranes & KCI
E. Zero salts

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4 Displays
4.1 Primary display - 3½ digit display providing direct readout of %
oxygen saturation, % air saturation, mg/l oxygen. Underrange (-1)
and Overrange (1) symbols will be displayed if the instrument is
reading outside the ranges as shown below:
Primary Ranges:
% oxygen saturation
-5 to 25.0%
% air saturation
-5 to 199%
mg/l oxygen
-5 to 19.99mg/l
4.2 Secondary display –4 digit display showing temperature (manual
temperature compensation value if used with a non-standard sensor,
or ATC temperature using the standard probe) in °C or °F.
Manually adjusted pressure values (Bar) and salinity values (g/l) will
be shown when the relevant mode is selected.
4.3 CAL annunciator –indicates when a calibration is being performed.
4.4 Battery Life Indication –4 levels will be shown ranging from 25%, 25-
50%, 50-75% and 75-100%. Sensor calibration data and user
parameters are retained during battery replacement.
4.5 Mode annunciator –indicates which mode of operation is selected.
4.6 MAN –this is displayed to indicate when manual temperature
compensation (only operates with non-standard probes or if the
temperature sensor in the probe is defective), salinity or pressure
value adjustment is being performed.
4.7 RCL annunciator –this indicates that the displayed reading is a
stored value recalled from internal memory.

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5 Controls
STO RCL
STO stores the current data reading.
RCL enters recall mode to view the stored readings.
I:O
Switches the instrument on and off. This key should
be pressed and held for 1-2 seconds to operate.
The instrument will automatically switch off after 30
minutes if no key is pressed.
Back light. Pressing this key will illuminate the back
light for 10 seconds. it should be noted that, if used
excessively, this will degrade battery life.
▲ ▼
Enables manual setting of DO2 calibration values
when performing a calibration, and adjustment of
the manual temperature compensation value,
pressure and salinity.
CAL
This key is used to select and perform DO2
calibration.
MODE
This key changes the primary measurement
parameter from %DO2 to mg/l, as required. When
temperature is displayed, holding this key for 3
seconds changes the display to read in °C or °F.
6 Preparation for Use
NOTE: Prior to using the chemicals listed, please refer to the Health &
Safety information at the rear of the manual.
The probe is delivered with the membrane module detached. Prior to use the
membrane module must be fitted to the probe body. A protective sheath is
also supplied. This should be fitted to the probe when not in use. The
sponge contained within the sheath should be wetted with deionised water
prior to fitting. This covers the membrane and keeps it wet, thus preventing
the electrolyte filling from drying out.
a. Remove the protective sheath from the probe.
b. Take a membrane module and hold in the vertical position. Fill with
the electrolyte solution (5% KCI) supplied with the instrument. Ensure
no air bubbles are trapped in the bottom of the membrane cap.

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c. Whilst still holding the module upright, screw the probe slowly down
onto the thread, allowing the excess electrolyte to escape through the
screw thread. Ensure no air bubbles are present and that the
membrane is not creased.
d. The probe should be connected to the instrument and left for 30
minutes to polarise, with the tip immersed in a beaker of water.
To maintain polarisation and to enable immediate use, it is recommended
that the sensor should be permanently connected to the instrument.
If the sensor is to be kept in extended storage, the membrane cap should be
removed and rinsed with water, and the sensor tip cleaned. The probe
should be stored dry without the wetting sheath fitted.
7 Operation
Connect the DO2probe to the instrument. Switch the instrument on by
holding down the I/O key for 1-2 seconds. All display segments will be
illuminated for approximately 2 seconds. An internal self check routine is run
during this display and on successful completion normal operating mode is
activated. The display will either power up in %DO2or mg/l mode depending
upon previous usage.
7.1 %DO2mode
This gives a direct readout of the %DO2of the sample under test as either %
oxygen saturation or % air saturation. When the instrument is calibrated to a
value of <25.0% the resolution will automatically increase to 0.1%.
8 Calibration
Prepare a zero oxygen solution by dissolving the contents of the vial
of sodium sulphite supplied with the instrument in 150mls of water.
Allow to stand for a few minutes prior to use.
Press the CAL key. Immerse the probe in the zero solution and stir gently for
approximately 2 minutes. Once the reading has stabilised press the Cal key.
The instrument automatically detects the zero solution and will calibrate the
reading to zero % dissolved oxygen, which will cause the primary display to
read zero. Remove the probe from the zero solution and rinse thoroughly
with deionised water.

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8.1 Air saturation
This will directly assign a percentage dissolved oxygen to air saturated
water and further readings are then given as a percentage of this air
saturated water sample. All measurements in this range are given to a
resolution of 1%.
Calibrate the probe in zero solution as above.
Fill a suitable container with a sample of clean water. Press the Cal key.
Hold the probe so that the membrane is close to, but not touching, the
surface of the water (approximately 1 cm above).
Once the reading has stabilised press the Cal Key.
This will cause the primary display to read 100% DO2.
8.2 % Oxygen saturation
This will give a reading of 20.9% in air where 20.9% is the amount of
oxygen as a percentage of oxygen in air and will give a reading
directly as a percentage of oxygen in the sample. All measurements in
this range are given to a resolution of 0.1%. Calibrate the probe in
zero solution (see section 8).
Fill a suitable container with a sample of clean water. Press the CAL key.
Use the ▲▼ keys to adjust the primary display to read 20.9%. The MAN
annunciator will be displayed. Hold the probe so that the membrane is close
to, but not touching, the surface of the water (approximately 1 cm above).
Once the reading has stabilised press the CAL key. The instrument
measures the manually entered value (20.9%). Once a calibration value is
set manually the instrument will automatically calibrate to this value until an
alternative value is entered.
8.3 mg/l
If measurements are to be performed in mg/l it will be necessary to
enter the current barometric pressure and salinity values.
8.4 Barometric pressure
Press the MODE key until the secondary display shows
the BAR annunciator for barometric pressure.
Adjustment to the correct value can be made by using
the ▲▼ keys.

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Fill a suitable container with a sample of clean water. Press the Cal
key. Hold the probe so that the membrane is close to, but not
touching, the surface of the water (approximately 1 cm above).
Once the reading has stabilised press the Cal key. This will cause the
primary display to read 100% DO2.
Press the Mode key to display pressure corrected mg/l readings.
8.5 Salinity
The oxygen dissolved in water decreases with increasing salinity when
making measurements in mg/l. If measurements are made in %
saturation then no correction is required.
Press the Mode key until the secondary display
shows the g/l annunciator for salinity. Adjustment
to the correct value can be made by using the
▲▼ keys.
The instrument is now ready to perform sample
measurements.
9 Performing Measurements
Select the mode required and immerse the probe in the sample to be
measured (40mm depth minimum). A flow rate of 15cm/min in the sample
is required to avoid errors due to oxygen starvation at the membrane. If
the flow rate is insufficient then the sample should be stirred (either by a
gentle stirring action with the probe or by use of a magnetic stirrer).
10 Data Storage
The dissolved oxygen meter can store up to 32 readings. Storage is
initiated by manual key press.
10.1 Storing data
Pressing the STO key stores the current reading in the next available data
location. The storage location is indicated by Sto and a number (1-32)
momentarily displayed prior to the data point. The results are stored
sequentially until the memory is full. When all 32 data locations are filled,
the next stored reading will overwrite the result previously stored in
position 1. The stored data is retained in the event of battery failure and
during battery replacement.

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10.2 Recalling data
Pressing the RCL key recalls the last stored reading onto the display.
The instrument is now in RCL mode, indicated by the RCL annunciator
at the top of the display.
The ▲▼ keys are used to select previously stored data. The storage
location is indicated by rCL and a number (1-32) momentarily
displayed prior to the data.
To clear all readings press and hold the CAL key (>3 seconds) while in
RCL mode. When all stored readings are cleared the display will
momentarily show CLr ALL. The instrument will then return to the
main operating mode.
If storage locations are empty and the RCL key is pressed, the display will
show ALL CLr.
NOTE: It is not possible to delete individual stored readings.
11 Good Practice Guidelines
a. Ensure the membrane is kept wet at all times. When not in use
the probe should be stored with the tip in a beaker of deionised
water. For longer periods (overnight) the protective sheath
should be fitted, with the sponge insert soaked in distilled
water. This will prevent the electrolyte fill solution from drying
out due to loss of water through the porous membrane.
b. Ensure the probe is polarised prior to use. It is essential to perform
this procedure after replacement of the membrane or probe. A 30
minute period of polarisation is required.
c. When replacing the membrane ensure no air bubbles are trapped in
the electrolyte fill solution and that the membrane is not creased or
damaged after fitting. If the probe response is sluggish, or the readout
is unstable after membrane replacement, clean the anode and
cathode (refer to Maintenance in Section 12).
d. The probe is fitted with a temperature compensating element. This is
housed underneath the silver ring on the probe body. Always ensure
the probe is immersed in solution to a depth suitable to cover this
ring. Allow sufficient time for these to respond if measuring samples
with varying temperatures or where sample temperature is
significantly different to ambient temperature.

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e. Ensure the sample is moving across the membrane at a speed
greater than 15cm/min to avoid oxygen starvation at the membrane. If
the flow rate is insufficient then the sample should be stirred (eg.
either by a gentle stirring motion with the probe or with a magnetic
stirrer).
f. When using the probe in liquors, sludges or polymers a coating may
be deposited on the membrane, causing slow response or drifting.
This can be reduced by rinsing the probe in deionised water, or a
suitable solvent for the sample, followed by a rinse with deionised
water after each test.
g. Ensure the probe is rinsed in deionised water after each test.
h. When measuring in mg/l (ppm) results are pressure dependent and
determinations carried out at pressures other than 760mm/Hg will
need to be compensated.
i. When measuring in mg/l (ppm) results obtained from saline samples
will need to be adjusted for salinity.
12 Maintenance
Although the oxygen probe is supplied in a clean and tested condition
it may, after some time, become sluggish or erratic due to
contamination of the gold cathode, silver anode or membrane.
12.1 Membrane replacement
a. Hold the probe in a vertical position and carefully unscrew the
membrane module.
b. Take the new membrane module and holding it in a vertical position,
fill with electrolyte (5% KCI).
c. Still holding the module in a vertical position, screw the probe slowly
down onto the thread, allowing excess electrolyte to escape through
the screw thread. Ensure no air bubbles are present and the
membrane is not creased.
12.2 Cathode and anode cleaning
The gold cathode tip can be re-polished using a fine abrasive (“crocus
paper”) material. Lay the abrasive sheet on a flat surface, hold the
probe in a vertical position and gently polish by moving the tip over the
sheet in a circular motion.
A toothbrush dipped in diluted ammonia solution will remove any deposits
from the silver anode. For stubborn deposits a very fine abrasive similar to
that used for cleaning gold connectors in electronics may be used sparingly.

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Rinse with deionised water prior to re-assembly. If the probe is not to be
used for 24 hours, store with the protective sheath fitted to prevent the
electrolyte from drying out due to evaporation through the membrane, which
is porous to water vapour as well as oxygen. If the probe is disconnected
from the unit or a new membrane has been fitted, it will be necessary to
allow the probe to polarise before stable readings can be obtained.
Polarisation will normally be achieved within 30 minutes.
13 Troubleshooting Guide
FAULT
PROBABLE CAUSE
ACTION
No power
Battery failure
Replace batteries
Battery polarity
incorrect
Refit batteries
Unstable display
DO2 probe defective
Replace DO2 probe
Probe not fitted
correctly
Check connections
Calibration to 100%
with zero solution
Repeat zero calibration
procedure with fresh zero
solution. Calibrate the probe
to 100% in air
Display
permanently
Intermittent or no
connection
Check electrode connection
to instrument
under or over
range
DO2 probe defective
Replace DO2 probe
Contaminated solutions
Replace solutions
Calibration on low
oxygen concentration
Recalibrate with the probe in
air
Temp. value
incorrect
DO2 probe defective
Replace DO2 probe
I/O switch not
working
I/O key not held down
long enough
Retry holding key for 2
seconds
Batteries not fitted
Fit batteries
▲▼ keys not
working
Operating in incorrect
mode
Refer to operation section of
manual
Back light not
on/goes out
10 second time
elapsed/ normal
function
Recheck

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FAULT
PROBABLE CAUSE
ACTION
Unable to adjust
manual
temperature
Incorrect mode of
operation
Reselect mode
Unable to
calibrate -
Sensor tip may be
tarnished (Ag or Au)
Clean the tip, replace
membrane module
Erratic or slow
response
Air bubbles inside the
membrane cap
Refill or replace membrane
Membrane damaged
Replace membrane
Coating of membrane
due to use in oils or
slurries, strong
solvents, acids or
alkalis
Replace membrane
DO2 probe defective
Replace DO2 probe
Inaccurate
calibration -
Zero solution will
absorb oxygen if left
Use fresh zero solution and
recalibrate
Erratic or slow
response
open
Measurement
Incorrect salinity
Reset salinity values
errors
Calibration error
Recalibrate instrument
Contaminated solution
Replace solution
Incorrect standards
Replace standards
Incorrect barometric
pressure
Reset barometric pressure
Unable to
calibrate to 100%
Calibrating to
previously set value
Manually reset value to
100%
Permanently
Membrane not fitted
Fit membrane
reading zero
Membrane damaged
Replace membrane
Membrane not filled
with KCI
Fill or replace membrane
DO2 probe defective
Replace DO2 probe
If a fault is identified during the start up self check routine, an error
code will be displayed. This indicates an internal hardware or software
problem. In the event of this, please contact the ELE Service
Department.

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14 Battery Replacement
Switch the unit off using the I/O key.
To fit new batteries; loosen the battery compartment cover (the screws
are captive in the cover), remove and carefully discard the used
batteries. Fit the new batteries, type R6, AA or AM3, ensuring the correct
polarities are observed, as indicated on the moulding. Refit the battery
compartment cover, ensuring that the fixings are secured into place, but
are not overtightened.
15 Auto Shut Off
This will occur after 30 minutes if no key is pressed.
16 Health & Safety Information
16.1 PRODUCT: Potassium Chloride Solution
HEALTH HAZARD –May be harmful if ingested in quantity,
causing nausea, vomiting and diarrhoea. May irritate eyes.
FIRST AID
Eyes: Irrigate thoroughly with water. If discomfort persists
OBTAIN MEDICAL ATTENTION.
Lungs: Remove from exposure.
Skin: Wash off thoroughly with soap and water.
Mouth: Wash out mouth thoroughly with water. In severe cases
OBTAIN MEDICAL ATTENTION.
16.2 PRODUCT: Sodium Sulphite Anhydrous
HEALTH HAZARD –If ingested in quantity can cause gastric
irritation, colic, diarrhoea, central nervous system depression
and death, due to liberation of sulphur dioxide. Irritating to skin,
eyes and respiratory system. Used in controlled quantities as a
food preservative and antioxidant.
FIRST AID
Eyes: Irrigate thoroughly with water for at least 10 minutes. If
discomfort persists OBTAIN MEDICAL ATTENTION.
Lungs: Remove from exposure, rest and keep warm. In severe
cases OBTAIN MEDICAL ATTENTION.
Skin: Wash off thoroughly with water. Remove contaminated
clothing and wash before re-use. In severe cases OBTAIN
MEDICAL ATTENTION.
Mouth: Wash out mouth thoroughly with water and give plenty
to drink. In severe cases OBTAIN MEDICAL ATTENTION.

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EC Declaration of Conformity
The 521-050 Dissolved Oxygen Meter complies with the following
European Standards:
EN 50081-1:1992 Electromagnetic compatibility –Generic emission
standard
EN 61326:1998 Electrical equipment for measurement, control and
laboratory use –EMC requirements.
EN 61010-1:1993 Safety requirements for electrical equipment for
measurement, control and laboratory use.
Following the provision of:
EMC Directive –89/336/EEC and
Low Voltage Directive –73/23/EEC


DIRECTIVE ON WASTE ELECTRICAL & ELECTRONIC EQUIPMENT
(WEEE)