Global Water
800-876-1172 • globalw.com
Global Water
Instrumentation, Inc.
151 Graham Road
P.O. Box 9010
College Station, TX 77842-9010
Telephone : 800-876-1172
International : (979) 690-5560, Fax : (979) 690-0440
e-mail : globalw@globalw.com
Turbidity Sensor
WQ750
Publication Number 39150712
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Manual Number : DFG005 Rev. C
Global Water
800-876-1172 • globalw.com
Congratulations on your purchase of a Global Water WQ750 Turbidity
Sensor. This instrument has been quali ty tested and approved for
providing accurate and reliable measurements. We are confident that you
will find the logger to be a valuable asset to your applications. Should you
require assistance, our technical staff will be happy to help.
Table of Contents
I. Checklist: 3
II. Inspection: 3
III. Warranty: 3
IV. WQ750 Specifications: 4
V. Introduction 5
VI. Electrical Connections 6
VII. Requirements: 6
VIII. Maintenance: 6
IX. Troubleshooting: 7
X. Customer Support: 7
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Copyright Global Water Instrumentation, Inc. 2012
I. Checklist:
a. WQ750 Turbidity Sensor
b. Wiper Timer Assembly
II. Inspection:
a. Your Turbidity Sensor was carefully inspec ted and certified by our
Quality Assurance Team before shipping. If any damage has occurred
during shipping; please notify Global Water Instrumentation, Inc . and
file a claim with the carrier involved.
III. Warranty:
a. Global Water Instrumentation, Inc. warrants that its products are
b. The warranty begins on the date of your invoice.
Global Water
800-876-1172 • globalw.com
free from defects in material and workmanship under nor m al us e
and service for a period of one year from dat e of shipm ent from
factory. Global Water’s obligations under this warranty are
limited to, at Global Water’s option: ( I) replace or (II) repair; any
products determined to be defective. In no case shall Global
Water’s liability exceed the produc ts original purchase price.
This warranty does not apply to any equipment that has been
repaired or altered, except by Global Water Instrumentation, Inc.,
or which has been subject to misuse, negligence or accident. It
is expressly agreed that this warr anty will be in lieu of all
warranties of fitness and in lieu of the war r anty of
merchantability.
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Copyright Global Water Instrumentation, Inc. 2012
Global Water
800-876-1172 • globalw.com
IV. WQ750 Specifications:
Turbidity S ensor:
Power: 10 VDC to 24 VDC
Current Draw: ~220mA @ 12 VDC
Operating Temperature 0ºC to 50ºC (32ºF to 122ºF)
Analog Sensor Output: 4-20mA Isolated
Signal Filter - 10 Seconds
Measurement Mode: 90º scattered light with pulsed infrared light,
according to ISO 7027 (DIN 38404)
Range: 1 – 1,000 NTU/FNU
Resolution: 12-bit
Operating Pressure: 6 bar (87 PSI) maximum
Timer Module:
Power Requirements: 10 VDC to 24 VDC, 50 mA
Operating Temperature: 0ºC to 50ºC (32ºF to 122ºF)
Sensor Housing:
Material: Housing: 316 SS
Wiper: Rubber
Sensor Window: Quartz glass
Dimensions: Diameter: 38 millimeters (~1.5 inches)
Length: 146 millimeters (~5.75 inc hes )
Process Connection: 1” BSPP
Weight: 0.7kg (1.4 lbs) without cable
Cable:
Conductors: 7 each 22 AWG
Shield: Aluminum foil/tinned copper wire
Cable length: 13 meters (~42.5 feet)
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Copyright Global Water Instrumentation, Inc. 2012
Global Water
800-876-1172 • globalw.com
V. Introduction
The WQ750 Turbidity Sensor is a sensor capable of m onitoring turbidity in water.
The turbidity sensor employs the 90 degr ee pulsed scattered light method with a
measuring frequency in the near-infrar ed light range of 880 nm, according to ISO
7027 (DIN 38404). Reflections from stationary objects in the area of the probe (e.g.
casing, wall, ground, etc.) c an aff ec t t he pr obe’s m eas ur ements at low turbidity
levels, causing the probe to falsely measure higher turbidity values. It is import ant to
take this into account when performing control measurements in small vessels. T he
distance between the probe and the next object should be large enough to avoid
reflections.
The sensor processes an analog 4 – 20 mA signal, which is s upplied by the sensor
electronics, after compensation of temperature and ambient light. A mechanical
cleaning wiper helps to prevent contam ination of the measuring windows.
An external timer module, which is included with the sensor, controls the wiper cycle.
The timer cycles the wiper for the first seven-sec ond per iod after the sensor is
requested to take a sample. The recommendat ion is to use a 15-second delay or
warm-up time to allow the wiper to complete its cycle before a sample is read.
Some potential applications for this sensor could be:
o Water Quality Monitoring
o Wastewater Plant Effluent Monit or ing
o Surface Water Monitoring of Lakes, Riv er s and Str eams
o Wastewater Recycle & Discharge
o Fish Farming
o Filtrate Monitoring
o Industrial Quality Control
o Condensate Monitoring
o Industrial Water Monitoring
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Copyright Global Water Instrumentation, Inc. 2012
VI. Electrical Connections
VCC
Input Voltage
GN
Ground
GN
Ground
WP
Wiper
VCC
GND
GND
WPR
Global Water
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VII. Requirements:
a. Power supply capable of delivering 10 VDC to 24 VDC (~ 270 m A
when sampling)
b. Logger or other equipment necessary to record sample data.
VIII. Maintenance:
a. Clean the sensor housing using clean water and a small, soft brush to
remove any debris.
b. Clean the quartz lenses with alcohol and a cotton swab.
Timer
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Copyright Global Water Instrumentation, Inc. 2012
Troubleshooting:
Issue: Sensor is reading incor r ec tly.
c. Verify the battery supply has enough voltage. T o oper ate properly, the
sensor must have a minimum of 10 volts.
d. Verify the sensor calibration is correc t
e. Clean the sensor windows to remove any cont am ination.
IX. Customer Support:
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 Email:
globalw@globalw.com.
When calling for tech support, have the following information ready:
1. Model number
2. Unit serial number.
3. P.O.# the equipment was purchased on.
4. Global Water sales number or the invoice number .
5. Repair instructions and/or specific 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.
In the event that the equipment needs to be returned t o the factory for any
reason, please call to obtain an RMA# (Ret ur n Material Authorization). Do
not return items without an RMA# displayed on the outside of the
package. Include a written statement desc ribing the problems.
Global Water
800-876-1172 • globalw.com
Send the package with shipping prepaid to our factory address. Insure
your shipment as Global Water’s w ar r anty does not cover damage
incurred during transit.
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Copyright Global Water Instrumentation, Inc. 2012
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