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TURBIDITY

 

WHAT IS TURBIDITY? 

Turbidity is an aggregate property of the solution, which is water in most 

cases. Turbidity is not specifi c to the types of particles in the water. 

The particles could be suspended or colloidal matter, and they can 

be inorganic, organic or biological. At high concentrations, turbidity 

is perceived as cloudiness, haze or an absence of clarity in the water. 

Turbidity is an optical property that results when light passing through 

a liquid sample is scattered. The scattering of light results in a change 

in the direction of the light passing through the liquid. This is most 

often caused when the light strikes particles in solution and is scattered 

backward, sideways and forward. If the turbidity is low, much of the light 

will continue in the original direction. Light scattered by the particles 

allows the particle to be ”seen” or detected in solution just as sunlight 

allows dust particles in the air to be seen.
In the past 10 years, turbidity has become more than just a measure 

of water clarity. Because of the emergence of pathogens such as 

Cryptosporidium and Giardia, turbidity now holds the key to assuring 

proper water fi ltration. In 1998, the EPA published the IESWTR (interim 

enhanced surface water treatment rule) mandating turbidities in 

combined fi lter effl uent to read at or below 0.3 NTU. By doing so, the 

EPA hoped to achieve a 2 log (99%) removal of Cryptosporidium. There 

is presently consideration to lower this to 0.1 NTU. The trend has been 

to check the calibration of on-line turbidimeters with hand-held fi eld 

units. The optical design and low detection limit of the 2020we/wi allows 

very accurate readings for such calibrations.
The meter also allows the user to choose the units of measure for 

expressing turbidity. While nephelometric turbidity unit (NTU) has 

been the standard for years, FNU (formazin nephelometric unit) and 

FAU (formazin attenuation unit) are now being used in ISO 7027 units. 

American Society of Brewing Chemists (ASBC) units and European 

Brewery Convention (EBC) units allow the brewing industry to check 

process waters.

 

HOW IS TURBIDITY MEASURED?

Turbidity is measured by detecting and quantifying the scattering of light 

in water (solution). Turbidity can be measured in many ways. There are 

visual methods and instrumental methods. Visual methods are more 

suitable for samples with high turbidity. Instrumental methods can be 

used on samples with both high and low levels of turbidity.
Two visual methods are the Secchi Disk method and the Jackson 

Candle method. The Secchi Disk method is often used in natural waters. 

A black and white Secchi Disk is lowered into the water until it can no 

longer be seen. It is then raised until it can be seen again. The average 

of these two distances is known as the “Secchi Depth”. The Jackson 

Candle method uses a long glass tube over a standard candle. Water 

is added or removed from the tube until the candle fl ame becomes 

indistinct. The depth of the water measured with a calibrated scale is 

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Summary of Contents for 2020we

Page 1: ...2020we wi 1970 EPA 1970 ISO...

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Page 3: ...t is Turbidity 13 How is Turbidity Measured 13 Turbidity Units 15 Taking Turbidity Water Samples 16 Sample Dilution Techniques 17 OPTIONS SETUP Factory Default Settings 17 Averaging 18 Turbidity Optio...

Page 4: ...erview 51 The Keypad 52 The Display and Menus 52 Negative Results 54 Tubes and Chambers 54 MAINTENANCE Cleaning 55 Repairs 55 Meter Disposal 56 4 Refer to the Quick Start Guide for simplified Calibrat...

Page 5: ...ater from wet tubes from entering the meter chamber NEVER PUT WET TUBES IN THE METER SAFETY PRECAUTIONS Read the label on all reagent containers Some labels include precautionary notices and first aid...

Page 6: ...9 NTU FNU Range 1 NTU FNU 110 4000 NTU FNU Range Accuracy From 0 2 5 NTU FNU the accuracy is 0 05 NTU FNU From 2 5 100 NTU FNU the accuracy is 2 Above 100 NTU FNU the accuracy is 3 Detection Limit 0...

Page 7: ...e analyte 1 Note that As Dr William Horwitz once stated In almost all cases when dealing with a limit of detection or limit of determination the primary purpose of determining that limit is to stay aw...

Page 8: ...independent of matrix glassware and other sample handling sources of error It is the detection limit for the optical system of the meter 1 CFR 40 part 136 appendix B 2 Statistics in Analytical Chemis...

Page 9: ...Standard 60 mL 1451 1454 Water Sample Bottle 60 mL 0688 0688 Tubes 6 Cable USB 3 ft 1720 1720 USB Wall Adapter 1721 1721 Accessories Code Description 1452 100 NTU Standard 60 mL EPA 1455 100 FNU Stand...

Page 10: ...2 years from the date of shipment If it should become necessary to return the instrument for service during or beyond the warranty period contact our Technical Service Department at 1 800 344 3100 fo...

Page 11: ...outlet Reinsert the USB port plug after charging To charge the battery from a computer plug the smaller end of the USB cable USB mini B connector into the meter and the larger end of the USB cable USB...

Page 12: ...he lithium ion battery used in this unit should last for many years with normal use When it no longer powers the unit long enough to meet testing requirements it will need to be replaced Lithium ion b...

Page 13: ...oridium There is presently consideration to lower this to 0 1 NTU The trend has been to check the calibration of on line turbidimeters with hand held field units The optical design and low detection l...

Page 14: ...ISO method are formazin nephelometric units FNU The 2020we meets the EPA specification and the 2020wi meets the ISO specification The nephelometric method is most useful for low turbidity The 2020we w...

Page 15: ...e light that is attenuated by high turbidity samples they may continue to report the results as NTU Recently there has been an effort to use the units of turbidity measurements to indicate which type...

Page 16: ...than 60 nm 180 detection 2020wi ISO 7027 ASBC American Society of Brewing Chemists 2020we wi Not applicable EBC European Brewery Convention 2020we wi Not applicable The 2020we and 2020wi each use two...

Page 17: ...L line with the sample and then transfer it to another container Add 10 mL volumes of deionized water to the container and mix Transfer 10 mL of the diluted sample to the colorimeter tube and follow t...

Page 18: ...iefly hold to turn the meter on The LaMotte logo screen will appear for about 3 seconds and the Main Menu will appear Main Menu Measure Data Logging Options Run PC Link 12 00 00 001 500 2 Press to scr...

Page 19: ...Press ENTER to save the selection The screen will display Storing for about 1 second and return to the Options Menu Options Menu Averaging Turbidity Options Set Clock Set PWR Save 12 00 00 001 500 NOT...

Page 20: ...ds and the Main Menu will appear Main Menu Measure Data Logging Options Run PC Link 12 00 00 001 500 2 Press to scroll to Options Main Menu Measure Data Logging Options Run PC Link 12 00 00 001 500 3...

Page 21: ...easurements will be made with the 180 detector only as indicated by AU attenuation units or FAU formazin anttenuation units on the display AU and FAU are numberically equivalent to NTU See page 15 for...

Page 22: ...Main Menu Measure Data Logging Options Run PC Link 12 00 00 001 500 3 Press ENTER to select Options Press to scroll to Turbidity Options Options Menu Averaging Turbidity Options Set Options Set PWR Sa...

Page 23: ...mazin Japan Standard 12 00 00 001 500 NOTE Stablcal standards below 50 NTU should not be used to calibrate the 2020we wi The diluent has a different refractive index than traditional formazin standard...

Page 24: ...00 3 Press ENTER to select Options Press to scroll to Set Clock Options Menu Averaging Turbidity Options Set Clock Set PWR Save 12 00 00 001 500 4 Press ENTER to select Set Clock The date is displayed...

Page 25: ...ER to select the final character The time and date will be saved and the screen will return to the Options Menu Options Menu Averaging Turbidity Options Set Clock Set PWR Save 12 00 00 001 500 25 Opti...

Page 26: ...l appear for about 3 seconds and the Main Menu will appear Main Menu Measure Data Logging Options Run PC Link 12 00 00 001 500 2 Press to scroll to Options Main Menu Measure Data Logging Options Run P...

Page 27: ...o scroll to desired setting Auto Shutoff Disable 5 Minutes 15 Minutes 30 Minutes 12 00 00 001 500 7 Press ENTER to save the selection The screen will display Storing for about 1 second and return to t...

Page 28: ...measurements to avoid interference from stray light NOTE The backlight feature uses a significant amount of power The longer the backlight is on the more frequently the battery will have to be charged...

Page 29: ...rol 10 Seconds 20 Seconds 30 Seconds 12 00 00 001 500 6 Press or to scroll to desired setting Backlight Time Button Control 10 Seconds 20 Seconds 30 Seconds 12 00 00 001 500 7 Press ENTER to save the...

Page 30: ...ging Options Run PC Link 12 00 00 001 500 2 Press to scroll to Options Main Menu Measure Data Logging Options Run PC Link 12 00 00 001 500 3 Press ENTER to select Options Options Menu Averaging Turbid...

Page 31: ...d return to the Options Menu To retain the current user level calibration settings press EXIT to abort the Factory Reset Options Menu Done Enter Continue 12 00 00 001 500 7 Press ENTER to return to th...

Page 32: ...Options Run PC Link 12 00 00 001 500 2 Press to scroll to Options Main Menu Measure Data Logging Options Run PC Link 12 00 00 001 500 3 Press ENTER to select Options Options Menu Averaging Turbidity...

Page 33: ...to the Options Menu Options Menu Set PWR Save aging Set Backlight Time Factory Reset Select Language 12 00 00 001 500 NOTE If the meter unintentionally switches to another language use the procedure...

Page 34: ...ter on The LaMotte logo screen will appear for about 3 seconds and the Main Menu will appear Main Menu Measure Data Logging Options Run PC Link 12 00 00 001 500 2 Press to scroll to Data Logging Main...

Page 35: ...01 500 6 Press EXIT to return to the Logging menu Press or to scroll to disable the logging options or erase the log Press ENTER to select the option The screen will display Storing for about 1 second...

Page 36: ...e used in the following examples For the most accurate results a user calibration should be performed The Japan Standard calibration mode as indicated by J in the Menu bar should be used only with Jap...

Page 37: ...mended that the meter be calibrated daily 1 Press and briefly hold to turn the meter on The LaMotte logo screen will appear for about 3 seconds and the Main Menu will appear Main Menu Measure Data Log...

Page 38: ...e most accurate results use the same tube for the blank and the sample l 6 Fill the tube to the fill line with the blank Pour the blank down the inside of the tube to avoid creating bubbles Cap the tu...

Page 39: ...lean tube 0290 or the same tube three times with the standard l 11 Fill the tube to the fill line with the standard Pour the standard down the inside of the tube to avoid creating bubbles Cap the tube...

Page 40: ...nt dark background with light characters will appear to indicate that the reading can be adjusted Turbidity WB F 0 99 NTU Scan Sample Calibrate 12 00 00 001 500 17 Press or to scroll to the concentrat...

Page 41: ...three times removing the tube from the chamber after each scan and reinserting the tube in the chamber with the same orientation The readings should be consistent Use the last consistent reading to c...

Page 42: ...the sample l 5 Fill the tube to the fill line with the sample Pour the sample down the inside of the tube to avoid creating bubbles Cap the tube 6 Wipe the tube thoroughly with a lint free cloth 7 Ope...

Page 43: ...ep is not as critical for samples above 10 NTU The meter should always be blanked before reading samples below 10 NTU 1 Press and briefly hold to turn the meter on The LaMotte logo screen will appear...

Page 44: ...d below 1 NTU the meter should be blanked with a 0 NTU Primary Standard or prepared turbidity free 0 1 NTU water For the most accurate results use the same tube for the blank and the sample l 6 Fill t...

Page 45: ...Done for about 1 second and then return to the Turbidity With Blank menu Turbidity WB F Scan Blank Scan Sample 12 00 00 001 500 10 Rinse a clean tube 0290 or the same tube three times with the sample...

Page 46: ...when diluted Turbidity Free Water The definition of low turbidity and turbidity free water has changed as filter technology has changed and nephelometric instruments have become more sensitive At one...

Page 47: ...ng at least two syringes full of deionized water through the filtering apparatus to remove foreign matter The first and second rinses should be discarded Turbidity free water as prepared with the foll...

Page 48: ...ace the filter and fill the syringe with approximately 50 mL of deionized water Filter the water into the storage container and save this turbidity free water 6 Repeat Step 5 until the desired amount...

Page 49: ...ow concentrations use the same tube for the blank and the sample 15 Always insert tube into the meter chamber with the same amount of pressure and to the same depth 16 Occasionally clean the chamber w...

Page 50: ...tside of acceptable range Dilute sample and test again Error1 High readings with 90 and 180 detectors Dilute sample by at least 50 and retest Lost in meter menus Reset to factory default settings Foll...

Page 51: ...le measurements The microprocessor and optics enable a dynamic range and auto ranging over several ranges Energy efficient LED light sources are used for ISO turbidity EPA turbidity uses a tungsten fi...

Page 52: ...ader displays the title of the current menu The footer line displays the time and the date the data logger status and the battery status The menu selection window is in the middle of the display betwe...

Page 53: ...t results or error messages or the LaMotte logo is displayed The top two lines of the display are used to display information in a large easy to read format The menus work in the same way as previousl...

Page 54: ...n indicate that the sample was at or near the detection limit This is a normal variation that results in a negative reading A large negative reading however is not normal and indicates a problem Some...

Page 55: ...ty in results Slight variations in wall thickness and the diameter of the tubes may lead to slight variations in the test results To eliminate this error the tubes should be placed in the chamber with...

Page 56: ...hazardous to health and the environment To avoid harm to the environment and natural resources the use of appropriate take back systems is recommended The crossed out wheeled bin symbol on the meter...

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Page 60: ...802 Washington Ave Chestertown Maryland 21620 USA 410 778 3100 800 344 3100 www lamotte com 1970 MN 02 01 12...

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