Transcript
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Turbidity SensorTS100
Edition 3.0
User
Manual
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Greenspan Customer Service+61 7 4660 1888
Technical Support When You Need ItThe correct choice of sensor should be supported by professional advice to ensure long termsuccess in the field. Greenspan Technical Services is dedicated to customer support andprovides assistance in the selection, installation, deployment and commissioning of sensors with afull range of consulting services.
A full technical support and field advice service can be accessed by ringing Customer Service on+61 7 4660 1888 between 8am - 6pm, 5 days a week.
All requests for information will be serviced within 24 hours.
All Greenspan products are designed, developed and manufactured in Australia and can besupplied at short notice.
Warranty Details
Greenspan warrants all new Greenspan products against defects in materials and workmanshipfor 12 months from the date of invoice. During the warranty period, we will repair or, at ouroption, replace at no charge a product that proves to be defective provided that it is returned,shipping prepaid, to Greenspan Technology Pty Ltd.
Greenspans liability and obligations in connection with any defects in materials andworkmanship are expressly limited to repair or replacement, and the sole and exclusive remedy inthe event of such defects shall be repair or replacement. Greenspans obligations under thiswarranty are conditional upon it receiving prompt written notice of claimed defects within thewarranty period and its obligations are expressly limited to repair or replacement.
This warranty does not apply to products or parts thereof which have been altered or repairedoutside of the Greenspan factory or other authorised service centre, or products damaged by
improper installation or application, or subjected to misuse, abuse neglect or accident. Thiswarranty also excludes items such as reference electrodes and Dissolved Oxygen membranes thatmay degrade during normal use.
Greenspan Technology Pty Ltd will not be liable for any incidental or consequential damage orexpense incurred by the user due to partial or incomplete inoperability of its products for anyreason whatsoever or due to inaccurate information generated by its products.
All Warranty service will be completed as soon possible. If delays are unavoidable customers willbe contacted immediately.
The sensors should not be dismantled unless under instruction from Greenspan. Incorrecthandling will void the warranty.
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Contents
1. INTRODUCTION
Overview 1Theory of Turbidity 1
Turbidity and Suspended Solids 2
Stream Water Turbidity 2
2. TURBIDITY MEASUREMENT
Formazin Definition 3
Calibration Considerations 3
3. THE HARDWARE
Overview 4
Sensor Design 5
4. INSTALLATION
Connection 6
General Methods of Installation 7
Typical Locations 7
Option 1: Non Turbulent Conditions 8
Option 2: High Turbulent Conditions 8
Other Considerations 8
Turbidity Deployment 9
5. CLEANING AND MAINTENANCE 11
6. QUICK CALIBRATION CHECK METHODChecking Calibration Using Calibration CupsTR100 12
Calibration of Turbidity Cups 13
7. FORMAZIN CALIBRATION METHOD
Test Setup 15
Formazin Standards from Ref Stock Suspension 16
Preparation of Formazin Standard 16Materials 17
Procedure 17Checking Standard Against a Hach Turbidimeter (Optional) 17Calibration Method 18
Preliminary Setup 18
Zero Checking 18
Full Scale Checking 18
8. REFERENCES 20
9. SPECIFICATION and CERTIFICATE of CONFORMANCE 21
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10. APPENDIX
Errors in Measurement 23
Bench Testing 23
Noise 23Offsets 23
Bubbles 23
Algae 23
Colour 23
Turbidity Sensor Cleaning Pump TP100 24Function 24
Installation 24
TP100 Specification 26
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INTRODUCTION 1
Overview
The Greenspan TS100 Turbidity Sensor utilises a high gain infrared optical
system to detect the back-scatter intensity of suspended particles
by transmitting a beam of 880nm wavelength and measuring the received
intensity of reflected light.
Advanced digital filtering techniques are used to eliminate ambient light and
stray signals from the measurement of data.
A current loop output of 4 - 20mA is provided on the TS100 Series Sensor.
The external optical surface is coated with a special polymer which resistsfouling from algae growth. It does not eliminate the problem but increases the
time between cleaning.
The sensor is packaged in a 316-grade stainless steel or Acetal co-polymer tube,
with
O ring sealed Acetal co-polymer end fittings. The design is rugged and well
proven and can withstand the harsh conditions found in any field environment
Theory of Turbidity
Turbidity is the term used to describe the reduction in water clarity or
"cloudiness" as perceived by the human eye caused by the scattering of light due
to particulate matter suspended in solution. The greater the turbidity, the more
cloudy the water. Increases in turbidity reduce the transmission of light.
Because most aquatic plant growth and marine organisms depend upon natural
light radiation for survival, and light penetration in water is dependent on the
clarity of the water, the measure of turbidity is useful for assessment of water
quality.
Due to the effects of erosion within catchment areas, tiny particles of clays, silts
or small organic particles are washed into water bodies. Industrial wastes and
sewerage can also contribute particles.
Oceanographers, Engineers and Geomorphologists who are studying the
movement of suspended sediments find turbidity a useful factor in defining
relative changes in sedimentation between sites.
The rate at which the water is moving limits the amount of suspended solids it
can carry.
The inherent simplicity of turbidity measurement allows for the continuous in-
situ gathering of data. This is very useful when monitoring rapidly varying
turbidity conditions, and it is the main advantage compared with the laboratory
sample method.
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Turbidity and Suspended Solids
Suspended particles in the water are the principle source of turbidity.
Assuming that the turbidimeter has been calibrated to give a linear response to
standards (such as Formazin) varying only in concentration, the relationship
between suspended solids concentration and turbidity depends mostly onparticle size, composition and particle concentration. Even in streams that
transport sand during storm event runoff, strong relationships between
suspended solids and turbidity have been observed. In such cases, the
turbidimeter is responding less to the coarse fraction, but because the
concentration of the fine fraction (the main source of turbidity) increases
proportionately with the concentration of the coarse fraction, the turbidity is an
adequate index of the total suspended load. The relationship between turbidity
and total suspended solids in this case is non-linear. A linear relationship
should only be expected in cases where the particle size, shape and composition
do not vary through time. (Ref: Gippel, AJSWC, 1994)
Stream Water TurbidityIf turbidity is established as an index of suspended solids, then considerable
savings will result from reduced labour costs for field sample collection and
laboratory analysis. Stream water turbidity is likely to reflect catchment
condition, so a catchment-wide network of continuously recording instruments
could be used in a surveillance role to identify areas of landslips, stream bank
disturbance, or inappropriate land use practices. (Ref: Gippel, AJSWC, 1994)
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TURBIDITY MEASUREMENT 2
Greenspan turbidity sensors are of the back scattering type and respond to theaverage volume scattering of particulate matter over a defined angular range.
Both particle size and concentration affect readings.
Output is calibrated in terms of NTU (Nephelometric Turbidity Units).
The instrument does not measure in absolute terms but relative to a Formazin
standard, (see below). A comparison is made of the intensity of scattered light by
a sample and the intensity of scattered light by a standard reference.
Formazin Definition
Formazin is a white insoluble polymer formed by the condensation reaction
between hydrazine sulphate and hexamethylenetetramine, (Ref: Gippel,
AJSWC, Nov 1994). It forms a mono disperse dispersion of approximately 2.5
m geometric mean volume particles (Gippel, 1988a ).
Formazin reference solution is supplied as 4000 NTU primary standard and is
diluted with high quality distilled water to lesser concentrations for calibration.
Secondary standards of Formazin are available from various manufacturer's,
often as a gel suspension or sealed latex suspension, and are stable for up to 1
year when properly stored.
Secondary standards provided with reference test equipment are usually used tostandardise the instrument before each reading. (Ref: Standard Methods, 1995)
Calibration ConsiderationsVarious Turbidity units have been used to reference turbidity measurement.
(JTU, NTU, FTU, EBC, CNU, FAU, FNU) they are not all equivalent and they
should not be confused with mass concentration.
ISO 7027 recommends the adoption of FNU (Formazin Nephelometric Units)
and FAU (Formazin Attenuation Units), (Ref: Gippel, AJSWC, Nov 1994)
The most recognised and widely adopted reference standard is Formazin,
one FNU is equivalent to one NTU, (Nephelometric Turbidity Units) so NTU
has been adopted by Greenspan for turbidity calibration.
Derived standards are only stable for a few days and therefore have to be
prepared each time the instrument is checked.
Proper laboratory handling is essential as Formazin is a suspected
carcinogen. A simplified method not requiring Formazin is provided
in this manual using Greenspan Turbidity Reference Cups TR100.
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THE HARDWARE 3Overview
The TS100 turbidity sensors utilise an infra-red optical system to measure
scattered reflected radiation across an angle of 30. Infra-red transmission is
used because light of this frequency is heavily attenuated in water, therefore the
beam penetration is reduced to practical limits and infra-red interference from
sunlight is also reduced with depth.
The sensor is constructed of environmentally inert materials, 316 stainless steel
and Delrin plastic. The form is cylindrical with the following dimensions:
Transmission LEDs
B. Reception Photodiode30
C. Infra-red Lens
Optical Head
A.A
B
C
C
Side ViewFront View
275
*44.4
25
TS100 Turbidity Sensor
All dimensions in mm
*47mm max for Delrin
Alignment Mark
A
Alignment Mark
Figure 1. Overview
The standard package includes:
1 316 stainless steel body- Delrin optional
2 Delrin sensor head
3 Delrin cable gland.
4 Optical filter lens
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Sensor Design
A digital synchronous detector system is used to eliminate common mode carrier
signals and effectively provide a narrow band limited signal path. This method
ensures minimal interference from stray light frequencies (ambient light) and
maximum reception of signal strength.
The optical system is embedded in epoxy compound for stability and
waterproofing and ensures an ambient light proof, mechanically robust
mounting.
Quality electronic components are used throughout for reliable long term
operation and boards can be easily accessed and serviced.
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INSTALLATION 4ConnectionThe TS100 is designed as a three wire 4-20mA current system and is nominally
powered by 12V DC. The sensor is normally supplied with open ended bare
wires for connection to power and external data logger.
The following diagram illustrates the wiring arrangement for the TS100.
50 ohm
o
o
9 27VDC,
typically +12V
Ground
Blue
Red
Green
Load or m A meter
Output
Power
TS
Figure 2. Connection
The input voltage range is 9-27V and it should be noted that as the quiescent
current is 80mA and at full scale the output current is 20mA the total is
1000mA. The resistance of the cable is 9 ohms per 100 metres, therefore a 25m
length of cable will give a voltage drop of :
100mA x 9 x 25 = 0.225V for the active red wire
100
This is duplicated for the return green wire:
0.225 + 0.225 = 0.450V
Therefore, approximately 0.45 volts less is developed across the sensor. That is, a
12V supply with 25m of cable will effectively provide 11.55V at the sensor.
The sensors are protected against reverse voltage occurrences and against
voltages of 2KV such as may occur during lightning storms. However, if using in
areas prone to lightning activity it is recommended that lightning arresters be
fitted to all input cables.
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General Methods of InstallationThe Greenspan Range of Water Quality Sensors can be installed into a variety
of applications including:
Rivers, Lakes and streams Bore Hole and groundwater wells
Tanks and Reservoirs
Wet Wells for Water and Sewer Systems
In all field applications, mechanical, electrical and physical protection of the
Sensor, cabling and associated fittings must be provided.
Consideration needs to be given for the protection against vandalism, animal
damage, theft and extreme weather conditions.
There are a many ways of positioning sensors in the field in order to ensure the
continuous collection of data and the safety of the device.
Some methods commonly in use are:
1. Floating Buoy for use at sea, can be installed with telemetry/cell phone
communications.
2. Suspended Sensor attached to a guide wire and winch board, which is
useful for profiling applications.
3. Fly wire across stream/river, sensor tethered to fly wire and fully
immersed.
4. Installed in PVC conduit with sensor emerging from the immersed end.
5. Sealed waterproof, self contained vessel including batteries and
continuous logging equipment. Excellent for concealment.
6. Strapped to pylon or post in areas that become submersed, cabled to
bank. Ensuring 100mm clearance from post.
7. Hand operation for spot readings.
Typical Locations
1. Edge of river/stream/lake embankment.
2. Side of boat/vessel.
3. Mounted within a stilling well off stream from main flow.
4. Mounted within drainage channels/pipes.
5. Suspended from dam walls.
6. Sensor anchored to bed of lake/stream.
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Field Installation must ensure:
The sensor is anchored or held in position or located so it is not subject to
any movement during normal operations.
Sensor is protected from direct sunlight to avoid high temperature
fluctuations Sensor is protected against high turbulence and possible debris loading
during flow events
Option 1: Non Turbulent Conditions
Where there is no possibility of the sensor being affected by turbulence it can be
suspended into the water body using a stainless steel hanger cable. For
example where the sensor is installed into a large water storage tank. The
sensor will hang vertically into the tank and not be subject to movement from
water movements. The stainless steel wire prevents loading of the sensor cable.In Sewer Wet Well and Water Tank applications where high turbulence and
debris loading may affect the sensor, the following minimum installation
standards must be followed:
Option 2: High Turbulent Conditions
Where turbulence and water movement will act on the sensor it is recommended
to mount the sensor in a stilling well or mounting cradle attached to the side of
the well. This could simply be a length of PVC pipe bolted to the well wall in
which the sensor is located or could be an extension pole with a sensor cradle at
the lower end. Potential ragging and debris build up on the sensor & cableshould be overcome by extending the stilling well to above the high water level
or by cable tying the sensor cable up the cradle mounting arm. The movement
of the sensor must be eliminated such that the sensor is not subject to twisting
motion from swirling water during pumping, or from sideways movement due to
ragging of the sensor.
In all sewer wet well applications regardless of the mounting system used it is
recommended to also utilise a stainless steel hanger cable* to prevent loading
the sensor cable during installation, removal and maintenance. The stainless
steel wire must be securely connected to the sensor using the hanger hook and
the sensor cable should be cable tied at regular intervals up the stainless wire.
An outer sheath of hose or tubing can be fitted over both cables to reduce
ragging and debris build up on the cables. At the top of the well the stainlesswire can be attached to a bolt or mounting point.
*Note, the stainless steel suspension, hanger cable can be provided by
Greenspan. (Part No 7SK-100)
Warning:Under no circumstances must the sensor be installed such that it can
collide with the sides of the well, or other solid objects within the well.
Sensor installation under these circumstances will lead to sensor
damage that will not be covered under our normal warranty
conditions. In these cases the sensor must be mounted into a cradle or
stilling well as per Option 2.
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Other Considerations
Environmental compatibility should be checked before using the sensors and
advice sought from Greenspan if any doubt exists. The 316 stainless body can be
used in a majority of situations but care should be taken against possible
corrosion in high Chloride, Sulphate or Ferric solutions.The body should always be totally immersed under the water to ensure that the
sensor is at water temperature and to also avoid any possible anodic/cathodic
action taking place on the stainless body at the water-air interface. At some
sites it has also been noticed that clamps used to support the sensor made of a
dissimilar metal to the 316 stainless body can cause spot corrosion due to
electrolysis.
Turbidity DeploymentWhen mounting turbidity sensors in water ensure a minimum clearance around
the optical head of 50 mm and approximately 250 mm forward to reducereflection from non-data surfaces. Note that reflection errors increase the closer
the transmit LED is to a reflective surface. Therefore in tight installations it is
preferable to rotate the sensor so that the Alignment Mark is furthest from the
reflective surface. The Alignment Mark on the head is positioned adjacent to the
transmit LEDs, see Diagram 1, page 4.
When installing in very shallow water immerse to at least 250-300 mm
minimum to prevent infra-red radiation from natural sunlight affecting
readings. It is preferable to point the sensor face down or at an angle.
Alternatively, process the resultant data file so that only data recorded in non
daylight periods is accepted.
When installing directly into a flowing medium, angle the sensor head such that
it is inclined at an angle of at least 45 to the horizontal and such that the
sensor lens is facing downstream. This will minimise the damage to the lens as
a result of impact from travelling particulate matter.
If using the model TP100 lens cleaning pump it is important to ensure pump is
primed prior to positioning sensor at depth. This can be achieved at just below
surface level by manually triggering the pulse line or driving it from a logger,
and checking for correct pump operation and then lowering sensor to the desired
depth.
To manually check the pump operation, press the test button located inside theTimer Controller unit or briefly connect the trigger wire from the pump to
ground, (negative pulse) or to +ve supply (positive pulse).
When the cleaning pump is activated the force of the water creates artificial
turbulence and if left untethered, can cause slight displacement of sensor
position. It is preferable that the logged readings do not coincide with the pump
activation cycle, which may lead to errors. To minimise this, do not start the
recording logger at the same time as the pump timer and tether the sensor.
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Most sediment transport occurs during storm events and flood conditions.
Protection from floating debris damage is an important consideration along with
adequate tethering of sensors.
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CLEANING AND MAINTENANCE 5
Protection of the lens surface is vital to maintain the accuracy of the calibration.
The prevention of algal growth and marine encrustations on the lens (and body
in general) is desirable. Both the polymer and Turbidity Cleaning Pump assist
in this process. Please refer to Appendix for further information on the Lens
Cleaning Pump.
The lens may be cleaned using warm soapy water, a soft cloth and a gentle
rubbing action.
WARNING
DO NOT USE METHYLATED SPIRITS or ALCOHOL on LENSSURFACE
If scratches are evident on the lens which cannot be removed through polishing
please contact Greenspan. It may be possible to recalibrate the offset to
eliminate the effects of the damage. Alternatively, the lens/head can be replaced
and the unit re-calibrated.
Note that regular cleaning of the lens will, in time, remove the polymer coating
applied during manufacture. Please contact Greenspan if you wish new coatings
to be applied.
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QUICK CALIBRATION METHOD 6
There are two methods in this manual for checking the calibration. The firstuses TR100 calibration cups and the second uses Formazin reference solution.
CHECKING CALIBRATION USING CALIBRATION CUPS TR100
To enable quick and easy checking of sensor calibration Greenspan can supply
calibration cups (TR100) matched to the particular sensor. There are two cups,
one for zero and one for full scale. These are simply slid over the sensor head
and the reading obtained should match the recorded reading taken when the
sensor was newly calibrated. Any difference will indicate that calibration has
changed.
NOTE: An individual cup will not measure the same turbidity value on
different sensors. The cup must be calibrated and matched to an
individual sensor prior to use. See Calibration of Turbidity Cups.
Method
1. Gently remove any debris which may have accumulated on the sensorhead with a moist soft cloth, avoid scratching the turbidity lens. Dry the
lens.
2. Remove the protective cap on the high and low turbidity calibration cupsand pour 2.5ml or 1/2 teaspoon of silicone oil into each and allow them to
form a level, bubble free layer over the calibration suspension in the base
of the cups.
3. Slide the low value turbidity calibration cup over the sensor head until itreaches the bottom, (some silicone oil may overflow). Rotate the cup,
while keeping firm contact on the bottom, to line up the alignment mark
on the cup with the mark on the sensor head.
4. Once the cup and sensor are in place and aligned, remove your handsfrom the sensor and allow the assembly to stand in a vertical position
(with the cup on the bottom) while taking the reading.
NOTE: Air bubbles trapped between the sensor lens and the
calibration suspension will cause high and erratic readings. Be
sure to use an adequate amount of silicone oil to prevent this
from occurring and ensure no air bubbles are present prior to
installing the cup. It is also important not to break contact with
the interface prior to reading the calibration point.
5. Connect the sensor output to a milliammeter. Check that the reading is
equivalent to the recorded value assigned to that sensor for that
calibrator cup.
6. Repeat steps 3-5 for the high calibration cup.
7. If the output reading is not within 3% of expected reading (value markedon Reference Table for that sensor) the sensor is out of calibration.
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8. Remove the cup and wipe the sensor head clean of oil with a soft cloth.
9. If re-calibration is necessary, contact a Greenspan authorised agent for
re-calibration.
CALIBRATION OF TURBIDITY CUPS
Function
Each cup and sensor must be matched prior to use in checking. If this was not
done at the factory, then the matching can be performed by the customer on the
bench using the following procedure. Note that this assumes that the sensor has
been accurately calibrated recently. Once matched the pair should remain
stable indefinitely.
Method
1. Gently remove any debris which may have accumulated on the sensor
head with a moist soft cloth, avoid scratching the turbidity lens. Dry the
lens.
2. Ensure that the sensor has been accurately calibrated, if not, return the
unit to a Greenspan authorised agent for re-calibration.
3. Engrave a permanent alignment mark laterally, anywhere along the
sensor head. Be careful not to scratch the sensor lens.
Alignment Mark
4. Clean and dry the sensor head with a soft cloth.
5. Remove the protective cap on the high and low turbidity calibration cups
and pour 2.5mL or teaspoon of silicone oil into each and allow them to
form a level, bubble free layer over the calibration suspension in the base
of the cups.
6. Slide the low value turbidity calibration cup over the sensor head until it
reaches the bottom, (some silicone oil may overflow). Rotate the cup while
keeping firm contact on the bottom, to line up the alignment mark on the
cup with the mark on the sensor head.7. Once the cup and sensor are in place and aligned, remove your hands from
the sensor and allow the assembly to stand in a vertical position (with the
cup on the bottom) while taking the reading.
NOTE: Air bubbles trapped between the sensor lens and the
calibration suspension will cause high and erratic readings. Be
sure to use an adequate amount of silicone oil to prevent this
from occurring and ensure no air bubbles are present prior to
installing the cup. is also important not to break contact with the
interface prior to reading the calibration point.
8. With the sensor output connected to a milliammeter. Record the reading ofthe sensor onto the Turbidity Reference Table in the calibrator kit, using a
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waterproof pen. Also, record the serial numbers of the turbidity sensor and
turbidity cup. These may be changed or removed later with methylated
spirits if the calibration is redone.
9. Repeat steps 6-8 for the full scale calibrator cup.
10. Remove the cup and wipe the sensor head clean of oil with a soft cloth.
Note that the same cup may be used on different sensors of the same range with
correspondingly different readings being obtained. Each reading is valid for that
particular sensor and all are recorded on the Turbidity Reference Table provided
in the TR100 kit.
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FORMAZIN CALIBRATION METHOD 7
Test Setup
A test setup such as the one described below is recommended for both zero and
full scale calibration checking. It is recommended the solution is kept moving
with a magnetic stirrer mounted underneath the full scale vessel to minimise
contact with solution.
The full scale calibration suspension using Formazin is prepared according to
Table 1. Allow a few minutes settling time for the Formazin to be evenly
distributed through the test vessel. See figure 3.
Magnetic stirrer mounted
underneath F/S vessel.
Clear Filtered WaterCalibration Suspension
5L Test Vessel F/S Set 20L Test Vessel Zero Set
oo- +
mA
Sensor Power Supply
Sensor
+12V, RED
Output, BLUE
Ground, GREEN
Can use magnetic stirrer for
minmum solution contact
Figure 3. Calibration Checking Setup TS100 Turbidity sensors
It must be considered that the validity of diluted Formazin Solution is time
dependant. For example, both "Standard Methods for Examination of Water and
Waste Water" and the US E.P.A recommend that 400 NTU suspension not be
used for longer than 30 days, and a 40 NTU value suspension no longer than 7
days if affected by light and temperature.
A sealable container of 5 litre capacity may be used for storage of Formazin and
calibration. The sensor should be held in the centre by means of a clamping
arrangement to eliminate side wall reflections. Ensure that the container used
for Formazin Calibration is a minimum size of 5 litres and has a diameter at
least 8 inches.
The zero solution should preferably be in a 20 litre container painted matt blackinside and well filtered water must be used.
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Materials
Hydrazine Sulphate (reagent grade) 5.000g
Hexamethylenetetramine (reagent grade) 50.00g
Procedure1. Set oven to 25C.
2. Transfer hydrazine sulphate to a 5000ml volumetric flask and add de-
ionised water to almost the mark. Stir to dissolve, then fill to the mark
with de-ionised water.
3. Transfer hexamethylenetetramine to a 5000ml volumetric flask and add
de-ionised water to almost the mark. Stir to dissolve, then fill to the mark
with deionised water.
4. Place both flasks in the 25C oven and allow to reach temperature.
5. Transfer all the contents of the hydrazine sulphate flask to a 10 litre
container equipped for magnetic stirring.
6. Slowly transfer all the contents of the hexamethylenetetramine flask to the
10 litre flask while stirring continuously.
7. Stop stirring when both solutions are mixed. Seal the 10 litre container
and allow to stand at 25C for 24 hours.
Checking Standard Against a Hach Turbidimeter (Optional)Mix the Formazin standard to be checked by making sure the lid is on tight and
then tumbling the canister several times (10 sec). Fill a clean Hach turbidity cell
with the standard, wipe the walls with silicone oil, and place it in a Hach 43900
Ratio/XR Turbidimeter. Record the readings when it is stable, (15 sec). Write
the value and date on the canister label. If the value has changed by more than
10% from its value at preparation, then prepare a new standard. Use the
standard within three days of checking.
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CALIBRATION METHOD
Preliminary Setup
Connect the sensor to +12V (red wire) and ground (green wire) and connect
current meter, (+), between blue and power supply common (-) green. See fig. 3.
Zero Checking
1. With power applied to the unit, place the sensor in the zero NTU bath at a
sufficient depth to cover the optical head and let the temperature
equilibrate for approximately 1/2 hour.
NOTE: Air bubbles trapped between the sensor lens and solution
will cause high and erratic readings. To reduce this, immerse the
sensor at an angle and if necessary gently rotate the sensor until
all bubbles surface.
2. If output reading is not within 3% of 4.00mA, contact a Greenspan
authorised agent for re-calibration.
3. After checking the zero value, rinse the sensor in clean water, wiping with
a tissue to remove excess water.
4. If zero reading is correct go to next section.
Full Scale Checking
1. Apply power to the magnetic stirrer and allow at least 15 min to give
circulation of the suspension.
Great care is necessary handling Formazin as it is a suspected
carcinogen.
2. Place the sensor into the test vessel prepared with a full scale NTU
Formazin solution. If there is any doubt about the accuracy of the solution
it is recommended it is checked on a Hach Turbidimeter. Ensure sensor is
in bath at a sufficient depth to cover the optical head. Ensure there areno trapped air bubbles by tilting the sensor slightly whenimmersing.
3. The expected reading can be calculated as follows:
Output (mA) = ( ( b x 16 ) + 4 )mA
a
where:
a = Full scale range of instrument (NTU)
b = Full Scale reading of Formazin Standard as measured by
laboratory instrument such as Hach Turbidimeter
for example:
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If sensor is a 500 NTU range and the Standard is 490 NTU
output (mA) = ( ( 490 x 16 ) + 4 ) mA = 19.68mA
500
4. If the output reading is not within 3% of the calculated value then re-
calibration is required. Contact a Greenspan authorised agent for re-
calibration.
5. After checking the full-scale value, rinse the sensor in clean water, wiping
with a tissue to remove any suspension material.
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REFERENCES 8
GIPPEL, C.J., 1989. The Use of Turbidity Instruments to Measure StreamWater Suspended Sediment Concentration. pp 12, Ch 2.
GIPPEL, C.J., 1988. Comparison of fine particle size determination by Coulter
Counter Model TA11 and Horiba CAPA-300. pp 11, Ch2.
GIPPEL, C.J., 1994. Monitoring Turbidity Of Stream Water, Australian Journal
of Soil and Water Conservation Vol. 7, No 4, pp 41.
Waterwatch Queensland Technical Manual., State of Qld, Department of
Primary Industries 1994. pp. 16.
STANDARD Methods for the Examination of Water and Wastewater, 19th
Edition 1995, 2130 Turbidity, 2-8 to 2-11
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SPECIFICATION and CERTIFICATE of CONFORMANCE 9
Specification Model TS100
Standard Ranges available 0-100NTU
0-250NTU
0-500NTU
0-1000NTU
Other ranges available on request.
-------------------------------------------------------------------------------------------------------------
Linearity 0-50NTU 3.0%
0-100NTU 3.5% or 3.0%*
0-250NTU 4.0% or 3.0%*
0-500NTU 9.0% or 3.0%*0-1000NTU 11.0% or 3.0%*
0-2000NTU 12.0% or 3.0%*
*NOTE: A linearity performance oftypically 3% for all ranges may be achieved by the use of
algorithmic data correction. Contact Greenspan Technology for further information .
-------------------------------------------------------------------------------------------------------------
Accuracy 3% FS (with algorithm)
--------------------------------------------------------------------------------------------------------------
Supply Voltage 9-27VDC
Reverse polarity protected
Surge protected to 2kV
--------------------------------------------------------------------------------------------------------------Quiescent Current 80mA
--------------------------------------------------------------------------------------------------------------
Warm up time to stable reading 2 Seconds
--------------------------------------------------------------------------------------------------------------
Output 4-20mA, 0-1V, 0-2.5V
--------------------------------------------------------------------------------------------------------------
Dimensions length 275mm,
44.5mm OD Stainless Steel
47mm OD Acetal co-polymer
--------------------------------------------------------------------------------------------------------------
Wetted Materials 316 Stainless Steel,Acetal co-polymer
--------------------------------------------------------------------------------------------------------------
Weight (potted) 735g, 316 Stainless Steel
605g, Acetal co-polymer
--------------------------------------------------------------------------------------------------------------
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TURBIDITY
SENSOR
22 Palmerin Street, Warwick 4370 Qld Australia.
Tel: 0746 601888 Fax: 0746 601800
CERTIFICATE of CONFORMANCE
Model No TS100
Customer:
Ref:
ProductDetail Serial No. 010410
Range 0 - 500 NTU
Output FS 20.00mA
Zero 4.00mA
Accuracy +/- 3 % of FS(with algorithm)
Linearity See User Manual
Cable Length 60 metres
Supply Voltage 9 - 27 VDC
Supply Current 80 mA
Connection: +ve Red
gnd Green
o/p Blue
Connection Code BW3
For further connection detail please refer toConnector Chart supplied.
User
Notes 1. The sensor is protected against reverse polarity.
2. Do not attempt to dismantle the sensor as it will void the warranty. Contact your agentfor technical advice.
2. The lens cover has been coated with an anti-fouling polymer to prevent marine growthaffecting accuracy.
3. The calibration instrument utilises a flow-through cell within a Hach Ratio Turbidimeterreferenced against Formazin solutions.
Inspected By ............ / /
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APPENDIX 10
ERRORS IN MEASUREMENT
Error variations can occur in data due to a number of factors:
1. Bench Testing The sensor is designed for intermittent sampling while fully
immersed. Therefore any readings taken in air are not valid.
They may only be used to indicate functional operation.
2. Noise Environmental transients greater than the mean signal
contribute to the background noise level. Also signal drift not
associated with the actual flow conditions is considered to be
noise. These can be caused by large floating debris, aquaticlife (fish) and installation lines obscuring the optical path
briefly.
3. Offsets Reflections from nearby surfaces of conduit, sea floor and
river bed can offset readings, allow a clearance of at least
250mm forward and 50mm to each side of the optical system.
4. Bubbles Trapped air bubbles on the filter lens. Can be removed by
tilting or stirring the sensor, positioning away from turbid
water inlets and using lens cleaning pumps.
5. Algae Algal growth will cause significant errors in as little as 35
hours in extreme conditions, if allowed to accumulate on the
lens. Regular cleaning and maintenance is essential, how
often this is required is dependent on the severity of the
micro-organism activity in the particular environment. A trial
period should be allowed initially to determine the cleaning
regime.
6. Colour Stream water in forested Australian catchments is often
coloured with Gilven. This component is leached from the
leaves of trees, particularly in areas dominated by barked
Eucalyptus. Gilven reduces Nephelometric turbidity by up to10%. Light sources with a wavelength of greater than 600 nm
are insensitive to Gilven such as the Greenspan
turbidimeters. (Ref Gippel 1989a).
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TURBIDITY SENSOR CLEANING PUMP TP100
FunctionTo maintain the optical cleanliness of the Turbidity Sensor by preventing
fouling due to algal growth. A high pressure jet of filtered water is periodically
forced across the lens dislodging any buildup of algae. When used in conjunction
with the non stick polymer an efficient method of cleaning is produced. This
system is particularly suitable for long term unattended data collection
situations.
InstallationThe unit conveniently clamps onto the TS100 sensor for easy installation and
removal. The power cable is strapped to the sensor cable and brought to the
surface for connection to the Timer Controller and battery.
The Controller unit can be programmed for various Intervals and turn-on
Durations by settings within the box. Please refer to the table below for settings
available.
Table 2.
Switch Setting Interval (Hours) Duration (Seconds)
0 1 2
1 2 5
2 3 10
3 6 154 12 30
5 24 60
6 48 120
7 72 240
The duration chosen can easily be tested by momentarily pressing the TEST
button located internally, this will activate the pump motor.
A positive or negative going 5-12V input trigger from an external logger or
Smart Sensor can also be fed to the Controller where a relay switched and timed
pulse of power is generated. Smartcom software can be programmed to pulse thepump at regular intervals. Background Sampling can be selected in Sampler
mode and is independant of the normal logged record interval. If the Smart
Sensor is used as the trigger source, a negative going pulse is output from the
sensor - please refer to the Smart Sensor user manual for connections.
Greenspan recommends the customer establishes a cleaning regime dependant
on environmental site conditions bearing in mind that the more often the pump
is turned on the shorter the lifetime of the battery. An initial interval of 3 hours
and a duration of 10 seconds is suggested as a starting point.
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If possible, it is preferable to test the assembled pump mounted on the sensor by
immersing near the surface prior to deployment at depth to verify operation and
pump priming.
The clamp can be removed from the sensor by undoing the two Allen key bolts
and sliding the assembly off the turbidity head. When repositioning, ensure thatthe dispersal nozzle vent hole is forward of the optical head lens to maintain the
water jet across the lens face.
The pump filter cap is a push fit onto the motor body and is easily removed for
cleaning.
Pump Motor
FilterInlet
Powe r Cable toCont rol Box
Optical Head
Disp ersal
Nozzle
Turbid ity Sensor
TP100Pump Clam p
Figure 4. Pump Installation
Note that the pump clamp has been designed to fit the optical head to allow for
the differences in outside diameter of the sensor tube depending on whether
Delrin body or stainless steel is used. When assembling the pump to the optical
head, push the sensor all the way to the end stop and tighten the locating
screws with a 2mm Allen key.
The power supplied to the Timer Control unit is internally regulated to
maintain timing consistency. The pump can be submerged to depths of up to
50m, with cable lengths up to 70m maximum. It is suggested cable ties are usedto attach the pump cable to the sensor cable.
It is recommended that a separate battery be used for the pump due to the
greater power required and the switching transients that may be present. It is
necessary however, to ensure a common ground between the pump power supply
and the sensor supply.
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SPECIFICATION TP100
Specification Model TP100
Connections Power +ve Red wire
Power Ground Black wire
Trigger Input User option, connections
internal
Supply line is protected internally with an
automatically reset polyfuse.
--------------------------------------------------------------------------------------------------------------
Dimensions 115 x 90 x 55 (mm)--------------------------------------------------------------------------------------------------------------
Power requirements 12 - 15VDC, typically 3 Amps. Supplies power to
both Timer Control unit and pump motor
--------------------------------------------------------------------------------------------------------------
Cable Maximum length 70 metres, with 12VDC supply
--------------------------------------------------------------------------------------------------------------
Supplied with 1 x Pump cable
1 x Pump filter cap
1 x Timer Control unit, providing a variable timed
pulse to the pump motor as well as an external
trigger pulse capability.
--------------------------------------------------------------------------------------------------------------
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