Global Water
800-876-1172 • globalw.com
Publication Number 38900512
Global Water
Instrumentation, Inc.
151 Graham Road
P.O. Box 9010
College Station, TX 77842-9010
T: 800-876-1172
Int’l: (979) 690-5560, Fax: (979) 690-0440
E-mail : globalw@globalw.com
Turbidity Meter: WQ770
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Global Water
800-876-1172 • globalw.com
Congratulations on your purchase of the Global Water WQ770
Turbidity Meter. This instrument has been quality tested and
approved for providing accurate and reliable turbidity
measurements. We are confident that you will find the WQ770 to
be a valuable asset for your application. Should you require
assistance, our technical staff will be happy to help.
Table of Contents
I. Checklist • • • • • • • Page 3
II. Inspection • • • • • • 3
III. WQ770 Operation • • • • • 4
IV. Battery Life and Replacement • • • • 5
V. Maintenance • • • • • • 5
VI. Troubleshooting • • • • • • 6
VII. Warranty • • • • • • • 7
VIII. Appendix A: WQ770 Calibration Procedures • • 8
IX. Appendix B: Turbidity Standard Solutions • • 11
* Copyright Global Water Instrumentatio n, I nc. 2012
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I. WQ770 Checklist
a. Turbidity Meter
b. Turbidity Sensor
c. 9V Lithium Battery (Inside Turbidity Meter Enclosure)
d. WQ770 Manual
The Turbidity Meter has been calibrated and ver ified at Global Water’s
facility prior to shipping, ther e is no need to recalibrate the meter until the
recommended maintenance period has elapsed.
II. Inspection
The Turbidity Meter was carefully inspect ed and c er tified by our Quality
Assurance Team before shipping. If any signific ant damage has occurred
during shipping, please notify Global Water Instrumentation, Inc . and f ile a
claim with the carrier involved.
Use the checklist to ensure that you hav e r ec eived every thing needed to
operate the WQ770.
Global Water
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III. WQ770 Operation
a. Before turning the unit on, make sur e that the sensor cable has
correctly been attached to the display. Push the cable connector
gently into the meter’s connector. The outer connector ring can be
turned and locked into place so the cable will not detach from the
meter during use.
b. Remove the battery cover fr om the meter and verify that a 9V lithium
battery is installed in the unit. Replace t he battery cover.
c. P r es s the Menu/On Button. This brings up the display that shows the
output from the turbidity sensor.
d. Press and hold the Menu/On button for 3 seconds to display the
Range menu. Use the Up/Down arrow buttons t o s elec t either the
0-50 or the 0-1000 NTU range then press Save.
Global Water
800-876-1172 • globalw.com
e. Press the Menu/On button again and use the Up/Down arrow keys to
select units of NTU or ppm then press Save. Pressing the Menu/On
button 6 more times returns to normal display m ode. The other menu
items are used for calibration and are described in Appendix A.
f. Place the sensor in the water to be tested. The meter will display the
turbidity of the water. Warning: Air bubbles in the water or under the
sensor shield will cause errors in the r eadings . These air bubbles
must be avoided when placing the sensor in the wat er .
g. The Turbidity Meter will automatically shut off after 6 minutes. To
continue reading the display past this time press the Menu/On button
prior to the meter shutting off.
h. Prolonged immersion in hot wat er will c aus e acceler ated aging of the
sensor optics and seals. Warning: Do not expose the sen sor to
water exceeding 50°C.
IV. Battery Life And Replacement
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Global Water
800-876-1172 • globalw.com
a. Battery life is dependent on m any v ar iables . Extreme heat and
extreme cold will shorten the life of a battery. A WQ770 in an
environment that has a sustained temperature of 23°C will run 5%
longer than a unit that has a sustained t em per ature of 0°C. Store your
WQ770 at room temperature and disconnect the battery when not in
use for long periods of time.
b. The Turbidity Meter battery will oper ate for 15 hours. The meter will
automatically shut off after 6 minut es .
c. The Turbidity Meter comes with a 9V Lithium batt er y . To replace the
battery, remove the battery com par tment cover on the back of the
meter. The battery can be removed using your finger s or gently using
a flat head screwdriver being careful not t o dam age the battery.
Ensure that the replacement batter y is cor r ec tly installed with the plus
terminal going to the plus side of the batter y c ompartment.
V. Maintenance
a. Global Water recommends check ing the calibration after the first
month of use, then checking every 6 months.
b. The optics of the sensor will develop deposit s ov er time and should be
cleaned once a week. The windows can be cleaned using lint free
cotton swabs and rubbing alcohol.
c. The meter will show the letters BAT in the lower left side of the display
when the battery voltage goes below an acceptable level. See the
Battery Life and Replacement section for more information.
VI. Trouble Shooting
Issue: Meter reading incorrectly
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Global Water
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a. Clean the sensor windows using a lint free cotton swab and rubbing
alcohol.
b. Verify there are no air bubbles under the sensor shield.
c. C hec k the meter’s calibration.
Other issues
d. Call Global Water for tech support: 800-876-1172 or ( 979) 690-5560
(many problems can be solved over the phone). Fax: (979) 690-0440
or E-mail:
globalw@globalw.com.
When calling for tech support, please have the following information
ready;
1. Model #.
2. Unit serial number.
3. P.O.# the equipment was purchased on.
4. Our sales order number or the invoice number .
5. Repair instructions and/or s pec ific problems relating to the
product.
Be prepared to describe the problem you are experiencing including
specific details of the application, installation, and any additional
pertinent information.
e. In the event that the equipment needs to be returned to the factory for
any reason, please call to obtain an RMA# (Return M aterial
Authorization). Do not return items without an RMA# displayed on the
outside of the package.
Clean and decontaminate the WQ770 if necessary.
Include a written statement describing the problems.
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VII. Warranty
a. Global Water Instrumentation, Inc. warrants that its products are free
b. The warranty begins on the date of your invoic e.
Global Water
800-876-1172 • globalw.com
Send the package with shipping prepaid to our factory address. Insure
your shipment, Global Water’s warr anty does not cover damage
incurred during transit.
from defects in material and workmanship under normal use and
service for a period of one year from date of shipment from factory.
Global Water’s obligations under this w ar r anty are limited to, at Global
Water’s option: (I) replacing or (II) repairing; any products determined
to be defective. In no case shall Global Water ’s liability exceed the
products original purchase price. This w ar r anty does not apply to any
equipment that has been repaired or altered, ex c ept by Global Water
Instrumentation, Inc., or which has been subject to misuse, negligence
or accident. It is expressly agreed that this warranty will be in lieu of
all warranties of fitness and in lieu of the warr anty of merchantability.
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Global Water
800-876-1172 • globalw.com
VIII. Appendix A: Turbidity Meter Calibration
Note: The following steps show how to calibrate the WQ770 Turbidity
Sensor using suspended polymer turbidity standards only.
General
a. The Turbidity Sensor is measuring turbidity in liquids by using a 90
degrees scatter nephelometer where a foc us ed beam is dir ec ted into
the monitored water. The principle is based on rec ommendations of
the international guideline IS O
7027. Two detectors receive light from
a source emitting 880 nm infrared light in a puls ed m ode. One
detector is placed opposite the sourc e, receiving the transmitted light,
and the other detector is placed at an angle of 90 degrees to the
incident light beam measuring side-sc attered light. The detected light
intensity is directly proport ional to the turbidity of the water.
b. The following supplies are required:
Stand with rod and clamp
Beakers, 500 or 1000 ml
1000 NTU Turbidity Standard
50 NTU Turbidity Standard
0.0 NTU Turbidity Standard
Distilled Water
The preferred and recommended turbidity standards are suspended
polymer solutions. These are EPA approved, non-toxic, and require
no mixing or stirring. Other types of standar ds such as Formazin can
also be used, but these require thorough mixing and m us t be used
with low speed stirring plates during t he c alibr ation process.
All the necessary turbidity standard solutions are available from Global
Water, contact the sales department for more information. See
Appendix B.
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Preparation:
a. Set up a test stand with a rod and clamp to hold the s ensor. Beakers
will be placed underneath the clamp so the sensor can be ins er ted into
the liquid.
b. The sensor must have the stainless st eel s ec tion of the body in contact
with the test solution. Install the sensor s o that the end of the sensor
is at least 3 inches from the bottom. If the sensor is too close to the
bottom, infrared light may be reflected from t he glass and ef fect the
measurements.
c. The lenses must be gently cleaned with a cotton swab and isopropy l
alcohol before each calibration step.
d. Fill a large beaker with distilled water . This will be used to rinse
solution from the sensor in between steps .
e. Fill three more beakers with 0.0 NT U Standard, 50 NTU Standard and
1000 NTU Standard. These beakers must be at least 500 m l in s iz e or
the end of the sensor will be too close to the bott om for accurate
calibration. This generally requires solution volumes of at least 500ml.
f. The calibration process should not be done in bright light if possible.
While not generally required, the ex tra step of covering the outside of
the beakers with a non-transparent mater ial m ay help to prevent stray
light from the outside affecting the readings .
Note: The sensor is factory calibrated and will pr ov ide output currents
of 20mA at the maximum turbidity values; however, some small drift in
this output current can occur over time. These adjustments are done
internally, access to these settings are not available to the user. The
sensors should never be disassembled. The following process
describes how to re-calibrate the meter and sensor to compensate for
any drift.
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Global Water
800-876-1172 • globalw.com
Calibration
a. If the sensor is not connected to t he met er , push the cable connector
gently into the meter’s connector. The outer connector ring should be
turned and locked into place so the cable will not detach from the
meter during use.
b. To enter the meter’s calibration scr eens hold the Menu/On button for
3 seconds. The first menu screen is for select ing the range. Use the
Down arrow key to select 50 NTU then press the Save button.
c. P r es s the Menu/On button to display the units available. Use t he
Up/Down arrow keys to select NTU (nephlom etric turbidity units).
Press the Save button to record the unit s elec tion. Press the Menu/On
button to move to the next menu.
d. The LoSig screen shows a number with NTU. This is not an indication
of the real NTU reading. This value includes meter offsets and other
variables.
e. You may use a lint free bent cotton swab t o remove any air bubbles
from underneath the detector window, ens ur ing that there are no
bubbles on the lenses is critical. Place the sensor into the distilled
water. Press the Save button until the display r eads “saved”. This
step may need to be repeated to ensure that an accurate reading is
taken. Press the Menu/On button t o move to the next menu.
f. The HiSig screen shows a number with NTU. This is not an indication
of the real NTU reading. This value includes meter offsets and other
variables.
g. Place the sensor in the clamp above the 50 NTU solut ion. Lower the
clamp and dip the sensor into the solution. Wipe t he detector window
with a cotton swab to remove any air bubbles. Press the S av e butt on
until the display reads “saved”. This step may need to be repeated to
ensure that an accurate reading is taken. P r ess t he M enu/O n button
to move to the next menu.
h. The LoLab screen displays the c or r ec t NT U reading f or the solution
used in the LoSig calibration step. For dis tilled water press the arrow
keys until the display reads 0 NTU. Pres s the Save but ton to record
the LoLab unit. Press the Menu/On button to move to the next menu.
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i. The HiLab screen displays the correct NTU reading for the solut ion
used in the HiSig calibration step. For 50 NTU solution, press the
arrow keys until the display reads 50 NTU. Press t he S av e butt on to
record the HiLab unit. Press the Menu/On button to move to the next
menu.
j. The delay screen indicates the time the meter will take to average
sensor readings. This should be set 5 seconds f or the best results.
Press the Menu/On button to return to the initial measuring screen.
k. Repeat steps b-j to calibrate the 1000 NTU range using the 1000 NTU
solution and distilled water. Use the Up arrow button to select the
1000 NTU range in step b and set the HiLab value to 1000 in step i.
IX. Appendix B: Turbidity Standard Solutions
The following turbidity standards ar e av ailable from Global Water, contact the Sales
Department or Technical Support for more information.
These are EPA approved primary standards that are safe, non-toxic and disposable.
They are easy-to-use with no dilution or re-suspension needed. Their inherent
stability means they do not settle from s us pens ion and r equir e no s tirring. The
convenient submicron polymer s us pens ions ar e non-toxic primary calibration
standards approved by the US EPA for drinking wat er analy s is for turbidity, and
preferred by the U. S. Geological Survey f or turbidity and sediment transport
analysis.
Part Number Description 02-003 0.0 NTU Turbidity Standard
02-004 50 NTU Turbidity Standard 02-005 100 NTU Turbidity Standard 02-006 1000 NTU Turbidity Standard
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