EUTECH INSTRUMENTS WATERPROOF C401 COLORIMETER User manual

Instruction Manual
C401/301/201/102/101
Portable Colorimeter
Technolo
g
y
M
ade
E
a
s
y
.
.
.
68X357704 Rev. 0 08/04

Preface
This manual functions in two ways: first as a step by step guide to help
you operate the waterproof C401/301/201/102/101 Colorimeter; second, it
serves as a handy reference guide.
It contains basic instructions that you must follow during the operation,
care and maintenance of the instrument. The safety protection provided by
this equipment may be impaired if it is used in a manner not described in
this manual. It is recommended that all operators should read this manual
prior to working with this instrument.
Eutech Instruments/ Oakton Instruments cannot accept any responsibility
for damage or malfunction to the meter caused by improper use of the
instrument.
The information presented in this manual is subject to change without
notice as improvements are made, and does not represent a commitment
on the part of Eutech Instruments Pte Ltd/ Oakton Instruments.
Note: Eutech Instruments Pte Ltd/ Oakton Instruments reserves the
right to make improvements in design, construction, and appearance
of our products without notice.
Copyright © 2004 All rights reserved.
Eutech Instruments Pte Ltd
Oakton Instruments
Rev. 0 08/04

TABLE OF CONTENTS
1INTRODUCTION ..................................................................................................................1
1.1 UNPACKING C401/301/201/102/101 COLORIMETER AND ACCESSORIES ...........................2
1.2 DISPLAY ............................................................................................................................3
1.3 KEYS AND FUNCTIONS.......................................................................................................4
1.4 BATTERY INSTALLATION...................................................................................................5
2MEASUREMENT ..................................................................................................................6
2.1 GENERAL INFORMATION....................................................................................................6
2.2 PREPARATION OF SAMPLE VIAL ........................................................................................7
2.3 MEASUREMENT PROCEDURE .............................................................................................7
2.4 CHLORINE,FREE &TOTAL (0 –6PPM CL2)........................................................................ 9
2.4.1 Sample Collection...................................................................................................11
2.4.2 Sample Measurement.............................................................................................. 11
2.4.3 Interferences ...........................................................................................................12
2.4.4 Correcting for dilution............................................................................................13
2.4.5 Accuracy Check / User Calibration........................................................................13
2.4.6 Chemistry................................................................................................................14
2.5 CYANURIC ACID (5-90 PPM)............................................................................................ 15
2.5.1 Sample Collection...................................................................................................17
2.5.2 Sample Measurement.............................................................................................. 17
2.5.3 Interferences ...........................................................................................................17
2.5.4 Accuracy Check / User Calibration........................................................................17
2.5.5 Chemistry................................................................................................................18
2.6 PH(5.9-8.2 PHUNITS) .....................................................................................................19
2.6.1 Sample Collection...................................................................................................21
2.6.2 Sample Measurement.............................................................................................. 21
2.6.3 Interferences ...........................................................................................................21
2.6.4 Accuracy Check / User Calibration........................................................................21
2.6.5 Chemistry................................................................................................................22
3CALIBRATION....................................................................................................................23
3.1 CALIBRATION PROCEDURE ..............................................................................................23
3.2 CHLORINE,FREE &TOTAL ..............................................................................................24
3.3 CYANURIC ACID..............................................................................................................27
3.4 PH.................................................................................................................................... 30
3.5 RESTORING FACTORY CALIBRATION...............................................................................33
4TROUBLESHOOTING GUIDE.........................................................................................35
5ROUTINE MAINTENANCE..............................................................................................36
5.1 VIALS –HANDLING,CLEANING AND CARE .....................................................................36
6ACCESSORIES....................................................................................................................37
7SPECIFICATIONS ..............................................................................................................38
8WARRANTY ........................................................................................................................39
9RETURN OF ITEMS...........................................................................................................39

Introduction C401/301/201/102/101
1
1 INTRODUCTION
Thank you for selecting the waterproof portable C401/301/201/102/101
Colorimeter. Depending on the model selected, the C401/301/201/102/101
Colorimeter allows you to measure up to four parameters - namely the pH,
Cyanuric acid, Free Chlorine and Total Chlorine of an aqueous sample in
the field. You have one of the following models:
•C101: pH measurement
•C102: Cyanuric Acid measurement
•C201: Free Chlorine and Total Chlorine measurement
•C301: Free Chlorine, Total Chlorine and pH measurement
•C401: Free Chlorine, Total Chlorine, Cyanuric Acid and pH
measurement

Introduction C401/301/201/102/101
2
1.1 Unpacking C401/301/201/102/101 Colorimeter and
Accessories
The table below indicates the items that you should find in your
Colorimeter shipment.
Item Quantity
1. Field Portable C401/301/202/102/101Colorimeter with 4 “AAA”
batteries
1
2. Instruction Manual 1
3. Instrument Carrying Case 1
4. Empty Vial 4
5. pH Indicator (Phenol Red) Reagent Kit (Only for C101, C301, C401) 1
6. Cyanuric Acid Reagent Kit (Only for C102, C401) 1
7. Free Chlorine DPD Reagent Kit (Only for C201, C301, C401) 1
8. Total Chlorine DPD reagent Kit (Only for C201, C301, C401) 1
Remove C401/301/201/102/101 Colorimeter from the packing carton.
Carefully inspect all items to ensure that no visible damage has occurred
during shipment. If the items you received do not match your order, please
contact your nearest distributor immediately.
WARNING: Extra care should be taken when unpacking, opening, and
handling the sample vials. Surface scratches or finger smudges on the vial
surface may cause measurement errors. Handle these items by their caps
only.
Batteries provided with the meter package are to be installed prior to use.
See Section 1.4 Battery Installation on page 5.
In the next page, Figure 1 depicts the meter. The three main components
of the instrument are the sample well, the display, and the keypad. The
following sections will describe the functionality of the display and the
keypad. The proper use of the instrument will be discussed in later
sections.

Introduction C401/301/201/102/101
3
Sample Vial
Sample Well
Meter Index
Marking
Liquid Crystal
Display
Keypad
Figure 1: Parts of C401/301/201/102/101Colorimeter
1.2 Display
All the LCD segments and annunciators that can appear on the display are
shown in Figure 2. The display is used for reporting the colorimeter
reading, communicate error messages and provide guidance for the
operation of the instrument.
CAL
ppm
pH
14-segment Liquid Crystal Display
Battery Indicator
Calibration Mode
Annunciator
Units of
Measure
Figure 2: Customized LCD when switched on

Introduction C401/301/201/102/101
4
1.3 Keys and Functions
The keypad has four keys: ON/OFF, MODE, ZERO and READ/ENTER.
Keys Functions
ON/OFF -Powers on and shuts off the meter. With the auto switch-off feature
the meter automatically shuts off 10 minutes after last key press.
MODE -Selects the test to be performed.
-Selects the calibration point in an incremental circular manner during
calibration.
ZERO -Blanks the instrument (sets the meter to zero) before chemical
reagent is added.
-Initiates the calibration mode when used with the ON/OFF key.
-Aborts the calibration process without saving.
-Exits the calibration mode.
READ /
ENTER
-Initiates the measurement of the sample after the chemical reagent
has been added.
-Confirms the test selection.
READ
ENTER
ZERO
MODE
OFF
ON
WATERPROOF
Figure 3: C401/301/201/102/101 Keypad

Introduction C401/301/201/102/101
5
1.4 Battery Installation
Four AAA-sized batteries are included in your meter’s packaging:
1. Use a Philips screwdriver to remove the two screws holding the
battery cover. See Figure 4 : Battery Installation.
2. Remove the battery cover.
3. Insert the batteries. Follow the diagram inside the cover for correct
polarity.
4. Replace the battery cover onto its original position using the two
screws removed earlier.
5. The meter is now ready to operate.
Philips Screws
Battery cover
Four 'AAA'-sized batteries
Figure 4 : Battery Installation
NOTE: Dispose used batteries in accordance with your local regulations.

Measurement C401/301/201/102/101
6
2 MEASUREMENT
2.1 General Information
The waterproof C401/301/202/102/101Colorimeter allows you to measure
up to four parameters - namely the pH, Cyanuric acid, Free Chlorine and
Total Chlorine of a sample and reports the results in appropriate units
(ppm or pH). Each specific measurement has its own range as listed in the
specifications.
The meter will go through a power sequence as shown below.
Meter’s Model Number Meter’s Revision Number Measurement Mode Selection
Figure 5: Power Up Sequence
An accurate colorimeter measurement depends on good measurement
techniques. Factors such as clean sample vials, positioning of vial in the
sample well, covering the vial with the light shield cap, meter calibration,
handling of meter, and others, have to be taken into consideration.
NOTE: Do not pour liquid directly into the sample well of the instrument.
Always use a vial. The instrument will only accurately measure the sample
when vials sealed with the black caps are used. The black cap serves as
both seal and a light shield.
NOTE: Do not attempt to clean the sample well. The optics may be
damaged.
NOTE: This instrument is designed to measure solutions contained in the
custom made glass vials and therefore the use of other type of sample vials
or sample cells may result in inaccurate measurements.

Measurement C401/301/201/102/101
7
2.2 Preparation of Sample Vial
1. Obtain a clean and dry sample vial (Figure 6).
2. Take care to handle the sample vial by the top.
3. Rinse the vial with approximately 10 ml of the sample
water, capping the vial with the black screw cap and gently
inverting it several times. Discard the used sample and
repeat the rinsing procedure two more times.
4. Fill the rinsed vial with the remaining portion (approximately
10 ml) of the grab sample up to the mark indicated in the
vial. Cap the vial with the supplied black screw cap.
5. Wipe the vial with a soft, lint-free cloth. Ensure that the outside of the
vial is dry, clean and free from smudges.
6. You are now ready to place the vial into the meter for measurement.
2.3 Measurement Procedure
1. Place C401/301/202/102/101Colorimeter on a flat and level surface.
2. Place the sample vial inside the sample well and align the vial’s mark
with the meter’s index mark. See Figure 8.
Align index mark on
the sample vial with
the index mark on
the colorimeter and
push till it is fully
snapped in
IMPORTANT :
Place meter on a flat
and level surface.
DO NOT hold it on
hands while operating
the meter. It may lead to
inaccurate readings
Figure 8: Sample vial index alignment to the meter's index mark
3. Push the vial until it is fully snapped in.
4. Turn on the meter by pressing the ON/OFF key. The display will
Figure 6:
Sam
p
le Vial

Measurement C401/301/201/102/101
8
indicate the last test performed
5. Select the desired test to be performed by pressing the MODE key.
6. Press the READ/ENTER key to confirm your selection. The meter will
display [STbY] indicating it is ready to accept a measurement or a
blanking.
7. Press the ZERO key to perform the blanking of the meter. If the user
chooses to skip this step, the meter will use the last value of the
blank for the next calculation.
8. Remove the sample vial used for blanking from the instrument and
add the appropriate reagent to it. Cap the vial and follow the
appropriate instructions (including the time required to develop the
color) for each type of reagents.
9. Place the vial with the developed color into the sample well and align
the ▼mark on the vial with the ▲mark on the instrument, and press
it down until it snaps fully into the optical holder.
10. Press the READ/ENTER key. The meter will display the reading in
appropriate units within 3 seconds.
11. To repeat the measurement of the same sample, repeat steps 7-11.
Ideally, step 7 should not be skipped, but the user may do so if
testing the same sample.

Measurement: Chlorine, Free & Total C401/301/201/102/101
9
2.4 Chlorine, Free & Total (0 – 6ppm Cl2)
•DPD method1for Free Chlorine - applicable to water, treated water,
estuary water and seawater.
•DPD method1for Total Chlorine - applicable to water, treated
water, wastewater, estuary water and seawater.
The DPD Method is USEPA accepted for reporting drinking water
analyses (Free and Total Chlorine) and wastewater analyses2(Total
Chlorine only).
Note: 1 Adapted from “Standard methods for the Examination of Water and
Wastewater.”
Note: 2Procedure is equivalent to USEPA method 330.5 for wastewater and
Standard Method 4500-Cl G for drinking water.
1. Switch the meter on by pressing the ON/OFF key.
2. Press the MODE key repeatedly until [CL – F] is displayed (for Free
Chlorine determination) or [CL – T] is displayed (for Total Chlorine
determination).
3. Press the READ/ENTER key to confirm the desired test parameter.
The meter will read [STbY] indicating it is in stand-by mode, waiting
for either blanking or measurement.
READ
ENTER
4. Select a clean and dry vial, un-screw the cap and fill with sample
water to the line on the vial. Replace the cap, ensuring it is screwed
on finger tight to the vial.
5. Ensure the outside of the vial is clean, dry and absent of any marks
or finger-prints. Gently push the vial fully into the sample well of the
instrument, whilst aligning the ▼mark on the vial with the ▲mark on
the meter.
6. Press the ZERO key to initiate blanking of the meter. The display will
show [ZERo] while blanking is taking place.
Note: The meter will store and use the last blanking (or zero) value, even if it
is turned off, or if the batteries are removed.
Blanking
Sample
ZERO
ppm

Measurement: Chlorine, Free & Total C401/301/201/102/101
10
7. Remove the vial from the meter and add into it the content of one
DPD Free sachet (for Free Chlorine determination) or the content of
one DPD Total sachet (for Total Chlorine determination).
8. Replace the cap, ensuring it is screwed on finger tight to the vial.
Invert the vial repeatedly for approximately 20 seconds, until the
powder has dissolved.
Note: A small amount of the powder may remain un-dissolved in the vial, but
this will not affect the measurement.
Add content of one DPD Free sachet
(for Free Chlorine determination) or
one DPD Total sachet (for Total
Chlorine determination).
Invert vial approximately
20 seconds until powder
dissolves
9. Gently push the vial back fully into the sample well of the meter,
whilst again aligning the ▼mark on the vial with the ▲mark on the
meter.
10. For Free Chlorine determination, press the READ/ENTER key within
two minutes from the time the DPD Free reagent was added to the
vial.
11. For Total Chlorine determination, wait for two minutes and then press
the READ/ENTER key within four minutes from the time the DPD
Total reagent was added to the vial.
12. The meter will flash either [CL-F] or [CL-T], depending on which test
is being performed, whilst the measurement is taken. It will then
display the Chlorine concentration in parts per million (ppm) Cl2.
Free
Chlorine
Sample
READ
ENTER
ppm

Measurement: Chlorine, Free & Total C401/301/201/102/101
11
2.4.1 Sample Collection
Chlorine determination must take place as soon as possible after the
sample is taken or else low results may be obtained.
Plastic containers should not be used to collect the sample because these
may have a high chlorine demand which will lead to low reading results. It
is advisable to wash the container with sample water before the sample is
collected.
Avoid agitating the sample excessively as this may also result in low
results.
2.4.2 Sample Measurement
If the pink color forms and then rapidly fades, this is an indication that the
chlorine concentration may be very high. If this is the case, dilute the
sample with de-ionized water and retest. Multiply the result by the dilution
factor used.
Example: if the sample was diluted 2:1 with de-ionized water (i.e. 1 part
sample water to 1 part de-ionized water), the result is multiplied by 2 to
give the true concentration of the original sample.
Note: Results obtained by this method will not be as accurate as stated in
this manual because some chlorine will be lost in the dilution process.
After use, the vial should be cleaned thoroughly to avoid contaminating the
next sample. Do not use household cleaners as these may have a
chlorine demand which will lead to low results on subsequent tests.
After testing Total Chlorine give extra attention to cleaning the vial as any
residual reagent will affect any subsequent Free Chlorine tests. It is
advisable to use separate vials for Free and Total Chlorine.
Chlorine, Free & Total
Measuring Hints & Tips

Measurement: Chlorine, Free & Total C401/301/201/102/101
12
2.4.3 Interferences
Acidity:
Greater than 250ppm CaCO3 may cause interference. To remove this
interference, neutralise a separate sample to pH6-7 using 1N Sodium
Hydroxide. Record the volume used and add the same volume of 1N
Sodium Hydroxide to the sample before carrying out the above test
procedure. Use a multiplication factor to correct for the dilution of the
sample.
Alkalinity:
Greater than 250ppm CaCO3 may cause interference. To remove this
interference, neutralise a separate sample to pH6-7 using 1N Sulphuric
Acid. Note the volumes used and add the same volume of 1N Sulphuric
Acid to the sample before carrying out the above test procedure. Use a
multiplication factor to correct for the dilution of the sample.
Hardness:
No effect at less than 2000ppm CaCO3.
Monochloramine:
Monochloramine will cause a gradual increase in the Free Chlorine result
over time. Take the test result within 1 minute of adding the reagent
sachet to avoid these errors.
Oxidants, including Bromine, Chlorine Dioxide, Iodine and Ozone:
These will interfere with the test method at all levels. It is recommended
that an alternative test method is used if these species are present.
Oxidised Manganese or Oxidised Chromium:
All levels will cause interference. To remove this interference:
1. Test a 10ml sample as described in the above procedure.
2. Adjust the pH of a separate 10ml sample to pH6-7 using 1N Sodium
Hydroxide or 1N Sulphuric Acid.
3. Add 1 drop of 20% Potassium Iodide Solution; swirl to mix and then
wait 60 seconds.
4. Add 3 drop of 5g/l Sodium Arsenite Solution and swirl to mix.
5. Use this as the sample in the above test procedure and make a note
of the result. Use a multiplication factor to correct for the dilution of
the sample.

Measurement: Chlorine, Free & Total C401/301/201/102/101
13
6. Subtract the result obtained in step 5 from the result obtained in step
1 to give the true result.
2.4.4 Correcting for dilution
To correct for any reagent added to the sample to neutralise it, a dilution
correction factor must be used:
Final Volume ÷ Initial Sample Volume = Correction Factor
The final volume can be calculated by adding together the initial sample
volume and the volume of neutralising reagent used:
Final Volume = Initial Sample Volume + Volume of Neutralising Reagent.
The result from a test can then be multiplied by the Correction Factor to
give the true result.
If reagents are added from the supplied dropper bottles, then 25 drops is
equal to 1ml.
Example:
50ml sample is neutralised using 50 drops of 1N Sulphuric Acid,
and each drop is 0.04 ml.
Initial Sample Volume = 50ml
Volume of Neutralising Reagent added = 50drops X 0.04 ml= 2ml
Final Volume = 50ml + 2ml = 52ml
Correction Factor = 52/50 = 1.04
A test result of 1.00ppm would then become 1.00ppm X 1.04 = 1.04ppm
2.4.5 Accuracy Check / User Calibration
Producing chlorine standards is a difficult procedure that should only be
attempted by trained laboratory staff. Details of preparation techniques are
not provided in this document.
The prepared chlorine standard may be used to check the accuracy of the
meter or to re-calibrate the meter. In almost all cases it is recommended
to use the default factory calibration.
To check the accuracy of the meter: Prepare a standard in the range 0-
6ppm (it is advisable to check a standard at near the concentration usually
tested for using the meter). Use this standard in place of the sample water
in the above test method. Repeat the measurement 5-7 times with
different sachets and average the results. The result obtained should be
approximately the value of the standard used (please refer to instrument’s
specifications for data on meter precision and accuracy).

Measurement: Chlorine, Free & Total C401/301/201/102/101
14
To re-calibrate the meter: All instruments are factory calibrated and user
calibration is not recommended. However, if a Chlorine standard can be
prepared, measured accurately and qualified by a different method
(titration, for example) or another instrument of higher precision and
accuracy, then a Chlorine standard in the 4.1-5.0 ppm Cl2range can be
used. Please refer to Section 3.2 Chlorine, Free & Total, for details.
2.4.6 Chemistry
Chlorine exists in water as Un-Combined (Free) Chlorine and Combined
Chlorine. The concentration of Free Chlorine can be determined directly
and the concentration of Combined Chlorine may be calculated by
subtracting the concentration of Free Chlorine from that of Total Chlorine.
In the Free Chlorine test method Un-Combined Chlorine reacts directly
with DPD (N,N-diethyl-p-phenylenediamine) in a conditioned sample to
give a pink color. In the Total Chlorine test method Combined Chlorine
reacts with potassium iodide to form tri-iodide ions. The tri-iodide ions and
the Free Chlorine present react with DPD in a conditioned sample to give
a pink color.
The depth of the pink color produced is proportional to the concentration of
Chlorine. The amount of 525nm light absorbed by the pink color is
accurately measured by the meter and then converted into the Chlorine
concentration.

Measurement: Cyanuric Acid C401/301/201/102/101
15
2.5 Cyanuric Acid (5-90 ppm)
•For water and treated water
1. Switch the meter on by pressing the ON/OFF key.
2. Press the MODE key repeatedly until [CYNA] is displayed.
3. Press the READ/ENTER key to confirm the test parameter. The
meter will read [STbY] indicating it is in stand-by mode, waiting for
either blanking or measurement.
READ
ENTER
4. Select a clean and dry vial, un-screw the cap and fill with sample
water to the line on the vial. Replace the cap, ensuring it is screwed
on finger tight to the vial.
5. Ensure the outside of the vial is clean, dry and absent of any marks
or finger-prints. Gently push the vial fully into the meter, whilst
aligning the ▼mark on the vial with the ▲mark on the meter.
6. Press the ZERO key to blank the meter to that vial; the meter will
read [ZERo] whilst this is taking place.
Note: The meter will store the last zero value it took between tests, even if it
turns off or if the batteries are removed.
Blanking
Sample
ZERO
ppm
7. Remove the vial from the meter and un-screw the cap. Select a
Cyanuric Acid reagent sachet. Open the sachet and tip the contents
into the vial.
8. Replace the cap, ensuring it is screwed on finger tight to the vial.
Shake the vial for 1 minute.
Note: a small amount of the powder may remain un-dissolved in the vial, but
this will not affect the reading.

Measurement: Cyanuric Acid C401/301/201/102/101
16
Add content of one
Cyanuric Acid sachet
Shake for
1 minute
9. Gently push the vial back fully into the sample well of the instrument,
whilst again aligning the ▼mark on the vial with the ▲mark on the
meter.
10. Wait for two minutes and then press the READ/ENTER key within
five minutes from when the sachet was added to the vial.
11. The meter will flash [CYNA] whilst the measurement is taken. It will
then display the Cyanuric Acid concentration in parts per million
(ppm).
Cyanuric
Acid
Sample
READ
ENTER
ppm

Measurement: Cyanuric Acid C401/301/201/102/101
17
2.5.1 Sample Collection
Samples may be collected in either plastic or glass bottles. It is advisable
to wash the container with sample water before collecting the sample.
Do not store the sample for more than 24 hours before conducting the
analysis.
2.5.2 Sample Measurement
Due to the nature of the test method, concentrations less than 5 ppm
Cyanuric Acid are not detectable.
Clean the vial immediately after taking and recording a reading. Do not
leave the sample with added reagent into the vial for more than few
minutes after measurement. The test will cause the build up of a cloudy
layer on the inside wall of the vial. It is important to thoroughly clean the
vial after use to remove this layer because subsequent test results may be
affected.
2.5.3 Interferences
Sample Turbidity:
Turbid samples should be filtered prior to analysis.
2.5.4 Accuracy Check / User Calibration
A stock solution of 1000ppm Cyanuric Acid may be produced by dissolving
exactly 1g of Cyanuric Acid in 1 litre of de-ionised water (check the purity
of the Cyanuric acid being used; if less than 100%, adjust the amount
used accordingly).
The stock solution may then be diluted to give a Cyanuric Acid standard.
To do this take a portion of the stock solution and make up to 1 litre using
de-ionised water (for example, 50ml of stock solution will produce a
50ppm standard).
To check the accuracy of the meter: Prepare a standard in the range
20-80 ppm (it is advisable to check a standard at near the concentration
usually tested for using the meter). Use this standard in place of the
sample water in the above test method. The result obtained should be
approximately the value of the standard used (please refer to instrument’s
specifications for data on meter precision and accuracy).
To re-calibrate the meter: All instruments are factory calibrated and user
calibration is not recommended. However, if a Cyanuric Acid standard can
Cyanuric Acid
Measuring Hints & Tips