Hach-Lange 2100NIS User Manual

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DOC022.52.80204

2100N IS

08/2012, Edition 2

User Manual

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Table of Contents

Specifications..................................................................................................................................................................................5

General information.....................................................................................................................................................................6

Safety information..............................................................................................................................................................................6

Use of hazard information..................................................................................................................................................................6

Precautionary labels..........................................................................................................................................................................6

Certification........................................................................................................................................................................................7

Product overview...............................................................................................................................................................................7

Product components..........................................................................................................................................................................8

User interface..................................................................................................................................................................................9

Startup...............................................................................................................................................................................................10

Turn the instrument on.....................................................................................................................................................................10

Turn the keypad sound off (optional)...............................................................................................................................................11

Standard operation....................................................................................................................................................................11

Calibrate the turbidimeter with StablCal® Standards.......................................................................................................................11

Prepare the StablCal standards................................................................................................................................................11

Calibration notes.......................................................................................................................................................................11

StablCal calibration procedure..................................................................................................................................................12

StablCal standards storage......................................................................................................................................................13

Using Gelex secondary standards...................................................................................................................................................13

Gelex notes...............................................................................................................................................................................13

Measure the Gelex stray light standard....................................................................................................................................14

Measure the Gelex secondary turbidity standards...................................................................................................................15

Calibration verification..............................................................................................................................................................16

Optical system check................................................................................................................................................................16

Prepare a sample cell......................................................................................................................................................................16

Clean the sample cell...............................................................................................................................................................16

Indexing a single sample cell....................................................................................................................................................17

Matching sample cells..............................................................................................................................................................19

Prepare dilution water...............................................................................................................................................................20

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Table of Contents

Prepare the sample..........................................................................................................................................................................21

Prepare a representative sample..............................................................................................................................................21

Remove air bubbles from the sample.......................................................................................................................................21

Apply a vacuum.................................................................................................................................................................21

Use an ultrasonic bath.......................................................................................................................................................21

Apply heat..........................................................................................................................................................................21

Prevent condensation on a sample cell....................................................................................................................................22

Measure over-range samples...................................................................................................................................................22

Sample dilution..................................................................................................................................................................22

Turbidity measurement....................................................................................................................................................................23

Measurement notes..................................................................................................................................................................23

Turbidity measurement procedure............................................................................................................................................24

Measurement techniques.................................................................................................................................................................25

Manual or automatic ranging....................................................................................................................................................25

Signal averaging on or off.........................................................................................................................................................25

Using the air purge system.......................................................................................................................................................25

Using a flow cell........................................................................................................................................................................26

Install a flow cell................................................................................................................................................................26

Clean a flow cell assembly................................................................................................................................................26

Flow cell maintenance.......................................................................................................................................................27

Flow cell operation.............................................................................................................................................................27

Flow cell storage................................................................................................................................................................27

Using a manual flow cell....................................................................................................................................................27

Use a cell adapter.....................................................................................................................................................................27

Install a cell adapter...........................................................................................................................................................28

Remove a cell adapter.......................................................................................................................................................28

Connect to a printer or computer.....................................................................................................................................................28

Configure the printer output.............................................................................................................................................................28

Configure the RS232 connection.....................................................................................................................................................28

Computer (RS232) commands........................................................................................................................................................29

Advanced operation..................................................................................................................................................................29

Calibrate the turbidimeter with formazin standards..........................................................................................................................29

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Table of Contents

Prepare formazin standards.....................................................................................................................................................29

Calibration notes.......................................................................................................................................................................30

Formazin calibration procedure................................................................................................................................................31

Making 4000-NTU formazin stock solution...............................................................................................................................32

Calibrate the turbidimeter with user-selected formazin standards...................................................................................................32

Prepare formazin standards – user selected............................................................................................................................33

Change the calibration points...................................................................................................................................................33

Maintenance...................................................................................................................................................................................33

Clean the instrument........................................................................................................................................................................33

Replace the LED light source..........................................................................................................................................................33

Replace a fuse.................................................................................................................................................................................33

Troubleshooting..........................................................................................................................................................................34

Error codes .....................................................................................................................................................................................34

Diagnostic codes..............................................................................................................................................................................35

Delete calibration data.....................................................................................................................................................................35

Flashing 9s.......................................................................................................................................................................................35

Flashing 0s.......................................................................................................................................................................................35

Replacement parts and accessories...............................................................................................................................36

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Table of Contents

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Specifications

Specifications are subject to change without notice.

Specification Details

Measurement method Nephelometric

Regulatory Meets ISO 7027, DIN EN 27027, DIN 38404 and NFT

Light source Light-emitting diode (LED) at 860 ± 30 nm

Measurement modes FNU and NTU

Range FNU (manual range): 0–0.999, 0–9.99, 0–99.9, 0–

Accuracy1,

Resolution Turbidity: 0.001 FNU/NTU (on lowest range)

Repeatability ±1% of reading or 0.01 FNU, whichever is greater

Response time Signal averaging off: 6.8 seconds

Stabilization time Immediately

Reading modes Manual or auto range, signal averaging on or off

9033

ASTM D7315 - Standard Test Method for Determination of Turbidity Above 1 Turbidity Unit (TU) in Static Mode

ASTM D6655 - Standard Test Method for Determination of Turbidity Below 5 NTU in Static Mode

1000

FNU (auto range): 0–1000

NTU (manual range): 0–0.999, 0–9.99, 0–99.9, 0– 1000

NTU (auto range): 0–1000

±2% of reading plus 0.01 FNU/NTU from 0– 1000 FNU/NTU

(under reference conditions)

Signal averaging on: 14 seconds (when 10 measurements are used to calculate the average)

Specification Details

Power requirement 115–230 VAC, 50/60 Hz (automatic power selection)

28 W maximum

Pollution degree/installation category

Protection Class 1

Operating conditions Temperature: 0 to 40 °C (32 to 104 °F)

Storage conditions –40 to 60 °C (–40 to 140 °F), instrument only

Interface RS232C serial interface by way of DB9 subminiature

Air purge Dry nitrogen or instrument grade air (ANSI MC 11.1,

Sample cells Round cells 95 x 25 mm (3.74 x 1 in.) borosilicate

Sample requirements 25 mm sample cell: 20 mL minimum

Enclosure High-impact polycarbonate plastic

Dimensions 30.5 x 40 x 15.6 cm (12.0 x 15.7 x 6.1 in.)

2; II

Relative humidity: 0–90% at 25 °C, 0–75% at 40 °C, noncondensing

Altitude: 2000 m (6560 ft) maximum

Indoor use only

D-shell connector for data output to computer or printer, and data input (command). No handshaking.

1975)

0.1 scfm at 69 kPa (10 psig); 138 kPa (20 psig) maximum

Hose barb connection for 1/8-inch tubing

glass with rubber-lined screw caps

Note: Smaller sample cells (less than 25 mm) can be used when a cell adapter is used.

0 to 95 °C (32 to 203 °F)

Note: Refer to Use a cell adapter on page 27 for the minimum sample size when not using a 25 mm sample cell.

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Specification Details

Weight 3.8 kg (8.5 lb)

Certification CE, cETLus

Turbidity specifications identified using recently prepared formazin standard and matched 1-inch sample cells.

Intermittent electromagnetic radiation of 3 volts/meter or greater may cause slight accuracy shifts.

General information

In no event will the manufacturer be liable for direct, indirect, special, incidental or consequential damages resulting from any defect or omission in this manual. The manufacturer reserves the right to make changes in this manual and the products it describes at any time, without notice or obligation. Revised editions are found on the manufacturer’s website.

Use of hazard information

D A N G E R

Indicates a potentially or imminently hazardous situation which, if not avoided, will result in death or serious injury.

Indicates a potentially or imminently hazardous situation which, if not avoided, could result in death or serious injury.

Indicates a potentially hazardous situation that may result in minor or moderate injury.

Indicates a situation which, if not avoided, may cause damage to the instrument. Information that requires special emphasis.

W A R N I N G

C A U T I O N

N O T I C E

Safety information

N O T I C E

The manufacturer is not responsible for any damages due to misapplication or misuse of this product including, without limitation, direct, incidental and consequential damages, and disclaims such damages to the full extent permitted under applicable law. The user is solely responsible to identify critical application risks and install appropriate mechanisms to protect processes during a possible equipment malfunction.

Please read this entire manual before unpacking, setting up or operating this equipment. Pay attention to all danger and caution statements. Failure to do so could result in serious injury to the operator or damage to the equipment.

Make sure that the protection provided by this equipment is not impaired. Do not use or install this equipment in any manner other than that specified in this manual.

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Precautionary labels

Read all labels and tags attached to the instrument. Personal injury or damage to the instrument could occur if not observed. A symbol, if noted on the instrument, will be included with a danger or caution statement in the manual.

This symbol, if noted on the instrument, references the instruction manual for operation and/or safety information.

Electrical equipment marked with this symbol may not be disposed of in European public disposal systems after 12 August of 2005. In conformity with European local and national regulations (EU Directive 2002/96/EC), European electrical equipment users must now return old or end-of-life equipment to the Producer for disposal at no charge to the user.

Note: For return for recycling, please contact the equipment producer or supplier for instructions on how to return end-of-life equipment, producer-supplied electrical accessories, and all auxiliary items for proper disposal.

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Certification

Canadian Radio Interference-Causing Equipment Regulation, IECS-003, Class A:

Supporting test records reside with the manufacturer.

This Class A digital apparatus meets all requirements of the Canadian Interference-Causing Equipment Regulations.

Cet appareil numèrique de la classe A respecte toutes les exigences du Rëglement sur le matériel brouilleur du Canada.

FCC Part 15, Class "A" Limits

Supporting test records reside with the manufacturer. The device complies with Part 15 of the FCC Rules. Operation is subject to the following conditions:

1. The equipment may not cause harmful interference.

2. The equipment must accept any interference received, including

interference that may cause undesired operation.

Changes or modifications to this equipment not expressly approved by the party responsible for compliance could void the user's authority to operate the equipment. This equipment has been tested and found to comply with the limits for a Class A digital device, pursuant to Part 15 of the FCC rules. These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial environment. This equipment generates, uses and can radiate radio frequency energy and, if not installed and used in accordance with the instruction manual, may cause harmful interference to radio communications. Operation of this equipment in a residential area is likely to cause harmful interference, in which case the user will be required to correct the interference at their expense. The following techniques can be used to reduce interference problems:

1. Disconnect the equipment from its power source to verify that it is or

is not the source of the interference.

2. If the equipment is connected to the same outlet as the device

experiencing interference, connect the equipment to a different outlet.

3. Move the equipment away from the device receiving the interference.

4. Reposition the receiving antenna for the device receiving the

interference.

5. Try combinations of the above.

Product overview

The 2100N IS laboratory turbidimeter measures turbidity in FNU (Formazin nephelometric units) and NTU (nephelometric turbidity units). NTUs are calculated using the conversion factors of 1.0 NTU per

1.0 FNU.

The turbidimeter has an RS232 output for connection to a printer, data logger or computer.

Figure 1 Front overview

1 Keypad 4 Cover for the sample cell

compartment

2 Sample cell holder 5 Five-digit LED display

3 Light shield

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Figure 2 Back overview

1 Power cord connector 4 DB9 connector for RS232 cable

2 Fuse holder 5 Air purge fitting

3 Power switch

Product components

Refer to Figure 3 to make sure that all components have been received. If any of these items are missing or damaged, contact the manufacturer or a sales representative immediately.

Figure 3 Instrument components

1 2100N IS turbidimeter 5 StablCal® Calibration kit

2 Oiling cloth 6 Gelex® secondary turbidity

3 Six 1" sample cells (30 mL) with

caps

4 Silicone oil 8 Power cord

Supplied with 4790000 only.

standardization kit

7 Dust cover

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User interface

Figure 4 Keypad

1 ENTER key 5 UNITS AVG key key

2 EDIT (arrow) keys 6 SETUP key

3 RANGE key 7 PRINT key

4 UNITS/Exit key 8 CAL key

Table 1 Key descriptions

Key Description

Enters the value on the display. Starts the measurement of a calibration standard. Clears data from the buffer.

Changes the numbers and/or letters on the display. Steps through the calibration standards. The right arrow key moves the cursor to the previous or next digit.

Table 1 Key descriptions (continued)

Key Description

Turns signal averaging on or off.

Turns on Setup mode and starts the selection of the setup number.

Sends the data that is on the display to a printer or computer. Sends a calibration data report to a printer or computer when in Calibration mode. Sends diagnostic results to a printer or computer if held down when the instrument is turned on. Provides a print of the setup commands when in Setup mode.

Starts or completes a calibration.

Selects automatic or manual ranging.

Selects the unit of measure. Exits Calibration or Setup mode without saving changes.

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Figure 5 Indicator lights

1 NTU light 6 CAL? light

2 FNU light 7 UNITS AVG light

3 Lamp light 8 SETUP light

4 Manual Range light 9 S0–S3 lights

5 Auto Range light

Table 2 Light descriptions

Light Description

NTU Illuminated when the instrument is set for NTU unit of measure.

FNU Illuminated when the instrument is set for FNU unit of measure.

Illuminated when the instrument light source is on.

Flashes when there is not sufficient light for measurement.

Table 2 Light descriptions (continued)

Light Description

Manual

Illuminated when the instrument is in manual ranging mode.

Range

Auto

Illuminated when the instrument is in auto ranging mode.

Range

CAL? Turns on during a calibration if the calibration data is not within the

acceptable range.

Flashes when the instrument should be calibrated.

Note: The CAL? light applies when a 25-mm sample cell is used. Ignore the CAL? light if illuminated during calibration when a smaller sample cell is used. Push UNITS/Exit to start measurements.

UNITS

Illuminated when signal averaging is on.

AVG

SETUP Illuminated when Setup mode is selected.

S0–S3 Show the current calibration point standard that is in use during

calibration.

Startup

Turn the instrument on

C A U T I O N

Infrared Light Hazard. The infrared light produced by this instrument can cause eye injury. The infrared light source in this instrument only receives power when the sample cell cover is closed.

1. Put the instrument on a stable, level surface that is free of vibration.

Do not put in direct sunlight.

2. Make sure that there is air circulation around the instrument. Keep

the back and area below the instrument free of material that could decrease air flow through the vents.

3. Connect the power cord to the power plug on the back of the

instrument.

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4. Connect the power cord to a power socket with ground contact.

5. Push the power switch on the back of the instrument to turn the

instrument on.

Turn the keypad sound off (optional)

By default, the instrument makes an audible sound when a key is pushed. To turn the keypad sound off:

1. Push SETUP. The SETUP light turns on.

2. Use the arrow keys to select 00.

3. Push ENTER.

4. Use the arrow keys to select the sound option:

Option Description

BP An audible sound is made when a key is pushed.

BP OF No sound is made when a key is pushed.

5. Push ENTER.

6. Push SETUP.

Standard operation

Calibrate the turbidimeter with StablCal® Standards

Calibrate the turbidimeter before it is used for the first time using the StablCal® sealed vial standards provided. As an alternative, calibration can be done with recently prepared formazin standards. Refer to

Calibrate the turbidimeter with formazin standards on page 29.

Calibrate the turbidimeter at least every 3 months or as specified by the regulating authority when data is used for ISO 7027 reporting.

Note: Unknown results may occur if standards other than the recommended calibration points are used. The recommended calibration points (< 0.1, 20, 200 and 1000 NTU) provide the best calibration accuracy. Use of standards other than StablCal, or user-prepared formazin, may result in less accurate calibrations. The manufacturer cannot guarantee the performance of the instrument if calibrated with co-polymer styrenedivinylbenzene beads or other suspensions.

Prepare the StablCal standards

When received and at intervals:

1. Clean the exterior surface of the StablCal vials with laboratory glass

cleaning detergent.

2. Rinse the vials with distilled or deionized water.

3. Dry the vials with a lint-free cloth.

Note: Never shake or invert the < 0.1 NTU standard. If the standard has been mixed or shaken, do not move the vial for 15 minutes or more before using.

Note: Do not remove the caps from the sealed vials.

Make sure that the StablCal standards are at ambient instrument temperature before use (and no greater than 40 °C (104 °F)).

Mix the standards before use:

1. Open the case lid. Remove the < 0.1 NTU standard from the plastic

case.

2. Leave the other standards in the case. Close the case lid.

3. Shake the case vigorously for at least 10 seconds.

4. Let the standards stand with no movement for 3–5 minutes before

use.

Calibration notes

• Make sure that the instrument is in the same ambient conditions as where it is used.

• Make sure that the standards are at the same ambient temperature as the instrument before use.

• Use only the provided silicone oil. This silicone oil has the same refractive index as the vial glass and masks minor glass differences and scratches.

• Store the oiling cloth in a plastic storage bag to keep the cloth clean.

• If power is lost during calibration, the new calibration data is lost and the last calibration data is used. To exit a calibration and not save the new values, push UNITS/Exit.

• In Calibration mode, automatic range and signal averaging on are selected. When calibration is completed, all operational modes go back to the last settings.

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• All nephelometric (turbidity units of measure) calibrations are done at the same time.

• The 4000-NTU standard does not have to be measured during calibration if FNUs will be measured. Push CAL after the 1000 NTU standard is measured to complete the calibration procedure.

StablCal calibration procedure

• The FNU values of StablCal standards and formazin standards are calculated using the conversion factors of 1 FNU = 1 NTU.

1. Push CAL.

The S0 light turns on. The NTU value of the dilution water used in the last calibration is shown on the display.

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2. Get the < 0.1 NTU

vial. Clean the vial with a soft, lint-free cloth to remove water spots and fingerprints. Do not invert the vial.

3. Apply a small bead of silicone oil from the top to the bottom of the vial.

4. Use the oiling cloth to apply the oil equally to the surface of the vial. Remove the excess oil. Make sure that the vial is almost dry.

5. Put the vial in the sample cell holder with the triangle on the vial aligned with the reference mark on the sample cell holder. Close the cover.

6. Push ENTER.

The instrument display counts down, then measures the standard.

The next expected standard (e.g., 20.00) is shown. The S1 light turns on.

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7. Remove the vial from the sample cell holder.

8. Do steps 5–10 for the other StablCal vials (from lowest to highest NTU standard).

The S0 light turns on after the last vial is measured.

9. Push CAL.

The instrument saves the new calibration data and goes back to Measurement mode.

StablCal standards storage

• Do not move a StablCal standard to a different container for storage. Keep StablCal standards in the plastic case provided with the cover closed.

• Store at 5 to 25 °C (41 to 77 °F).

• For long-term storage (more than one month between use), keep at 5 °C (41 °F).

Using Gelex secondary standards

The Gelex secondary standards are used when a calibration check or an optical system check is done. Refer to Calibration verification on page 16 and Optical system check on page 16.

Gelex notes

• Measure the Gelex secondary standards on the instrument on which they will be used. The measured values can only be used for one

instrument due to small differences in glass and instrument optical systems.

• Do not keep a Gelex vial in the instrument for more time than is necessary to complete measurement. The heat from the lamp can change the turbidity value of a Gelex vial.

• Keep the Gelex standards at room temperature. Do not let Gelex standards freeze or become warmer than 50 °C (122 °F). High temperatures may cause Gelex suspensions to divide.

• Make sure that the Gelex standards are at ambient instrument temperature before measurement.

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Measure the Gelex stray light standard

Measure the Gelex stray light standard when the instrument is first received. Record the value on the Gelex vial with a permanent marker one time.

1. Clean the stray light standard with a soft, lint-free cloth to remove water spots and fingerprints.

7. Put the stray light standard in the sample cell holder with the triangle on the vial aligned with the reference mark on the sample cell holder. Close the cover.

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2. Apply a small bead

of silicone oil from the top to the bottom of the vial.

8. Read the value when stable. Remove the vial from the instrument.

3. Use the oiling cloth to apply the oil equally to the surface of the vial. Remove the excess oil. Make sure that the vial is almost dry.

9. Record the value on the white diamond space on the vial using a permanent marker.

4. Push RANGE to select automatic ranging.

The Auto Range light turns on.

5. Push UNITS AVG to turn signal averaging off.

The UNITS AVG light turns off.

6. Push UNITS/Exit to select the NTU measurement mode.

The NTU light turns on.

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Measure the Gelex secondary turbidity standards

Measure the Gelex secondary turbidity standards each time the instrument is calibrated and record the new values on the Gelex vials with a water soluble marker.

1. Clean the Gelex vials with a soft, lint-free cloth to remove water spots and fingerprints.

7. Put the 0–2 NTU Gelex vial in the sample cell holder with the triangle on the vial aligned with the reference mark on the sample cell holder. Close the cover.

2. Apply a small bead of silicone oil from the top to the bottom of the vial.

8. Read the value when stable. Remove the vial from the instrument.

3. Use the oiling cloth to apply the oil equally to the surface of the vial. Remove the excess oil. Make sure that the vial is almost dry.

9. Record the value on the white diamond space on the vial using a water soluble marker.

Record on the vial if Ratio was on or off when the vial was measured.

4. Push RANGE to select automatic ranging.

The Auto Range light turns on.

10. Do steps 7–10 for the other Gelex vials (but not the stray light standard). Measure from lowest to highest NTU.

5. Push UNITS AVG to turn signal averaging off.

The UNITS AVG light turns off.

6. Push UNITS/Exit to select the NTU measurement mode.

The NTU light turns on.

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Calibration verification

At intervals, measure the Gelex secondary turbidity standard that is closest in value to the turbidity range to be measured. Do the steps in

Measure the Gelex secondary turbidity standards on page 15, but do not

change the value that is recorded on the vial.

If the measured value is within ±5% of the value recorded on the Gelex vial, calibration is verified. If not, calibrate the instrument.

Note: The StablCal® primary turbidity standards can also be used to do a calibration check. Prepare the StablCal vials before use. Refer to Prepare the

StablCal standards on page 11. Do not use the < 0.1 NTU StablCal vial as it does

not have an accurately identified NTU value. The instrument is calibrated if the measured value is within ±5% of the StablCal value.

Optical system check

At intervals, measure the Gelex stray light standard to inspect the integrity of the optical system. Do the steps in Measure the Gelex stray

light standard on page 14, but do not change the value that is recorded

on the vial.

If the value measured is similar to the value recorded on the Gelex stray light standard (within ±0.02 NTU), the instrument works correctly. If not, contact Customer Service.

Prepare a sample cell

Use a clean sample cell(s) for sample measurement.

Note: As an alternative, a flow cell can be used for sample measurement. Refer to

Using a flow cell on page 26.

Clean the sample cell

C A U T I O N

N O T I C E

Do not air dry the sample cells. Always store the sample cells with caps on to prevent the cells from drying. For storage, fill the sample cell with distilled or demineralized water.

1. Clean the internal and external surfaces of the sample cell and cap

with a laboratory glass cleaning detergent.

2. Fully rinse the sample cell many times with distilled or deionized

water.

3. Clean the internal and external surfaces of the sample cell and cap

with 1:1 hydrochloric acid.

4. Fully rinse the sample cell many times with distilled or deionized

water.

Note: If the sample cell will be used to measure low range turbidity samples or dilution water, rinse with dilution water (not distilled or deionized water). Refer to Prepare dilution water on page 20.

5. Dry the external surface of the sample cell with a soft, lint-free cloth.

6. Fill the sample cell with distilled or deionized water.

Note: If the sample cell will be used to measure low range turbidity samples or dilution water, fill the sample cell with dilution water (not distilled or deionized water).

7. Immediately put the cap on the sample cell.

Note: Hold the sample cell by the top only to minimize dirt and fingerprints.

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Chemical exposure hazard. Obey laboratory safety procedures and wear all of the personal protective equipment appropriate to the chemicals that are handled. Refer to the current material safety data sheets (MSDS) for safety protocols.

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Indexing a single sample cell

When measuring very low turbidity samples, use a single indexed sample cell or a flow cell for all measurements to get precise and repeatable measurements. As an alternative, optically matched sample cells can be used. Refer to Matching sample cells on page 19. Matched sample cells do not provide as good of accuracy and precision as a single indexed sample cell that is used for every measurement or a flow cell.

1. Rinse a clean, empty sample cell two times with dilution water and drain to waste. Fill the sample cell to the line (about 30 mL) with dilution water and immediately put the cap on the sample cell. Refer to Prepare

dilution water

on page 20.

Let the sample cell sit for at least five minutes to degas.

2. Clean the sample cell with a soft, lint-free cloth to remove water spots and fingerprints.

3. Apply a small bead of silicone oil from the top to the bottom of the sample cell.

4. Use the oiling cloth provided to apply the oil equally to the surface of the sample cell. Remove the excess oil. Make sure that the sample cell is almost dry.

5. Put the sample cell in the sample cell holder. Close the cover.

Record the value when stable.

6. Remove the sample cell, turn it about 1/8 of a turn and put it in the sample cell holder again. Close the cover.

Record the value when stable.

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7. Repeat step 6 until

the lowest value is shown on the display.

8. Put an orientation mark on the marking band near the top of the sample cell where the lowest value is shown.

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Matching sample cells

To decrease the effects that optical differences among sample cells can have on turbidity measurements, measure samples in matched sample cells. It may not be possible to match all sample cells due to the differences in glass.

1. Rinse two or more clean, empty sample cells two times with dilution water and drain to waste. Fill the sample cells to the line (about 30 mL) with filtered dilution water and immediately put the cap on the sample cell. Refer to Prepare

dilution water

on page 20.

Let the sample cell sit for at least five minutes to degas.

2. Clean the sample cells with a soft, lint-free cloth to remove water spots and fingerprints. Do not invert the sample cell.

3. Apply a small bead of silicone oil from the top to the bottom of the sample cells.

4. Use the oiling cloth provided to apply the oil equally to the surface of the sample cells. Remove the excess oil. Make sure that the sample cells are almost dry.

5. Put the first sample cell in the sample cell holder. Close the cover.

Record the value when stable.

6. Remove the sample cell, turn it about 1/8 of a turn and put it in the sample cell holder again. Close the cover.

Record the value when stable.

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7. Repeat step 6 until

the lowest value is shown on the display.

13. Do steps 9– 12 again as necessary to match the other sample cells prepared in steps 1–4.

8. Record the value. Put an orientation mark on the marking band near the top of the sample cell.

9. Put the second sample cell in the sample cell holder. Close the cover.

Record the value when stable.

10. Remove the sample cell, turn it about 1/8 of a turn and put it in the sample cell holder again. Close the cover.

Record the value when stable.

11. Repeat step 10 until the value matches the first sample cell value within ±0.005 FNU.

12. Put an orientation mark on the marking band near the top of the sample cell where the lowest value is shown.

Prepare dilution water

Dilution water is used when indexing a sample cell or matching sample cells and to prepare formazin standards.

1. Collect at least 1000 mL of high-quality, low-turbidity water (i.e.,

distilled, demineralized or deionized water or filtered tap water).

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2. Measure the turbidity of the water using the turbidimeter. Refer to

Turbidity measurement on page 23.

3. If the turbidity of the water is greater than 0.5 NTU, filter the water

using the sample filtration and degassing kit. Refer to the user instructions provided with the sample filtration and degassing kit.

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Prepare the sample

Proper sampling techniques are important to get accurate measurements.

Prepare a representative sample

A representative sample accurately reflects the true condition of the water source from which the sample was taken.

To prepare a representative sample:

• Gently but fully mix every sample before collecting aliquots (sample portions). Mix by gentle inversion only. Do not shake.

• When collecting a sample from a water tap in a distribution system or treatment plant, turn the water on for at least five minutes, then collect the sample.

• When collecting a sample from a body of water (e.g., a stream or storage tank), collect at least one liter (1 quart) and fully mix before taking an aliquot for measurement. If the quality of the sample source is not constant, collect samples at many locations at different depths as necessary. Then, mix the samples together to prepare one sample for measurement.

Remove air bubbles from the sample

If readings are not stable, air bubbles may be the cause. Remove air or other gases from the sample before measurement even if no bubbles can be seen.

The methods typically used for degassing are:

• Let the sample stand for several minutes

• Apply a vacuum

• Use an ultrasonic bath

• Apply heat

Let the samples stand for several minutes, then gently invert two or three times before measurement.

In some cases, more than one method may be necessary to remove bubbles (e.g., the use of heat with an ultrasonic bath may be necessary in some severe conditions). Use care with these methods as sample turbidity can be changed if these methods are not used correctly.

Apply a vacuum

Apply a vacuum with any available, clean, oil-free vacuum source, such as the sample degassing kit, or an electric or hand-operated pump equivalent to those in Accessories on page 36. The vacuum lowers the atmospheric pressure above the sample letting trapped gas bubbles exit.

Vacuum works well with samples that are not viscous, such as water, and do not contain volatile components. Application of vacuum to viscous, volatile samples (i.e., paint resins) may cause volatile components to come out of solution, and increase the bubbles.

Use an ultrasonic bath

An ultrasonic bath removes gas bubbles from most samples, especially viscous liquids. The time necessary to remove bubbles may be a few seconds to a minute or more.

To identify the time necessary for ultrasonic treatment:

1. Apply ultrasound to the sample for a short period of time, then

measure turbidity. Record the value and the treatment time.

2. Do step 1 again until there is no change in the turbidity of the

sample.

Note: In some instances, the use of ultrasound may divide gas bubbles and make them more difficult to remove.

To use an ultrasonic bath:

1. Fill a clean sample cell with sample. Do not put the cap on the

sample cell.

2. Put 1/2 to 2/3 of the sample cell into the ultrasonic bath and let it stand

until visible bubbles are removed.

3. Remove the sample cell from the ultrasonic bath and put the cap on.

4. Fully dry the sample cell.

Apply heat

C A U T I O N

Make sure that the cap on the sample cell is loose. Increasing the temperature of a tightly-capped sample cell may cause an explosion. More caution should be taken when increasing the temperature of volatile compounds.

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If possible, do not use heat to accelerate degassing. Heat may change the properties of the suspended particles and cause volatile components to come out of the solution.

Gentle heat may be used to remove bubbles from very viscous samples when used with vacuum or ultrasound. If applying heat to the sample is necessary, do so only as much as is necessary to complete degassing. Before measurement, decrease the temperature of the sample to the initial temperature, then gently invert the sample.

Prevent condensation on a sample cell

Condensation may occur on the outside of the sample cell when measuring a cold sample in a warm, humid environment. This condensation or fogging of the sample cell interferes with turbidity measurement.

To prevent condensation:

• Make sure that the outside of the sample cell is dry before measurement.

• Use the air purge system as necessary. Refer to Using the air purge

system on page 25.

• If condensation occurs while using the air purge system, warm the sample slightly. Let the sample sit at room temperature or partially put the sample into a warm water bath for a short time. Gently invert the sample cell before measurement.

Note: Warming may change the sample turbidity. Measure the sample without warming when possible.

Measure over-range samples

The nephelometric method of turbidity measurement depends on light scattering from suspended particles. If turbidity is very high, significant amounts of light may be absorbed by the particles, and little light is available for scattering. This results in a negative interference causing the measured turbidity to be lower than the actual turbidity. This condition is called “going blind”.

Methods used to prevent the instrument from going blind include:

• If measuring in the FNU mode, change the measurement units to NTU by pushing UNITS/Exit. The NTU measurement mode (with Ratio on) increases the measurement range.

• Sample dilution. Refer to Sample dilution on page 22.

When too much light is absorbed by the sample, the lamp icon on the instrument display flashes.

Sample dilution

Use filtered sample, deionized water or distilled water for sample dilution. Measure sample dilutions soon after they are prepared.

To prepare filtered sample, use the sample filtration and degassing kit. Refer to the user instructions provided with the sample filtration and degassing kit.

If the filters in the sample filtration and degassing kit plug quickly, use a standard 47 mm filtration apparatus shown in Figure 6 with a membrane filter or use a glass-fiber filter. Refer to Accessories on page 36.

After dilution and measurement, calculate the actual turbidity as follows:

1. Calculate the total volume:

Total volume = sample + dilution water

Example: 20 mL of sample and 80 mL of dilution water

Total volume = 20 mL + 80 mL = 100 mL

2. Calculate the dilution factor:

Dilution factor = total volume ÷ sample volume

Example: Dilution factor = 100 ÷ 20 = 5

3. Calculate the actual turbidity:

Actual turbidity = measured value × dilution factor

Example: Measured value = 2450 NTU

Actual turbidity = 2450 × 5 = 12,250 NTU

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Figure 6 Prepare filtered sample using membrane or glass-fiber filter

1 Filter pump 4 Stopper 7 Filter

2 Hose 5 Filter holder

3 Filter flask 6 Tweezers

Turbidity measurement

W A R N I N G

Potential explosion and fire hazard. This instrument is for measuring water based samples. Do not measure solvent or combustible based samples.

For accurate turbidity readings use clean sample cells and remove air bubbles. Refer to Clean the sample cell on page 16 and Remove air

bubbles from the sample on page 21.

Measurement notes

Proper measurement techniques are important in minimizing the effects of instrument variation, stray light and air bubbles. For accurate and repeatable measurements:

Instrument

• Make sure that the instrument is on a level, stationary surface that is free of vibration during the measurement.

• Instrument stabilization is immediate. No warm-up time is necessary.

• Always close the sample compartment lid during measurement, calibration and storage.

• Remove the sample cell from the instrument and turn off the instrument if the instrument is stored for an extended time period (more than a month).

• Keep the sample compartment lid closed to keep dust and dirt out.

Sample cells

• Always cap the sample cell to prevent spillage of the sample into the instrument.

• Always use clean sample cells in good condition. Dirty, scratched or damaged cells can result in readings that are not accurate.

• Make sure that cold samples do not “fog” the sample cell. Refer to

Prevent condensation on a sample cell on page 22.

• Store sample cells filled with distilled or deionized water and cap tightly.

• For the best accuracy, use a single sample cell for every measurement or a flow cell.

Note: As an alternative, matched sample cells may be used for measurements but do not provide as good of accuracy or precision as a single indexed sample cell or flow cell. When using matched sample cells, align the orientation mark on the sample cell with the reference mark on the sample cell holder.

Measurement

• Measure samples immediately to prevent temperature changes and settling. Before a measurement is taken, always make sure that the sample is homogeneous throughout.

• Avoid sample dilution when possible.

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• Avoid instrument operation in direct sunlight.

Turbidity measurement procedure

1. Rinse a clean,

empty sample cell two times with the solution to be measured and drain to waste. Fill to the line (about 30 mL) with sample and immediately put the cap on the sample cell.

7. Read and record the value when stable.

Note: To send (via RS232) a measurement record, push PRINT.

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2. Clean the sample

cells with a soft, lint-free cloth to remove water spots and fingerprints.

3. Apply a small bead of silicone oil from the top to the bottom of the sample cells.

4. Use the oiling cloth provided to apply the oil equally to the surface of the sample cells. Remove the excess oil. Make sure that the sample cells are almost dry.

5. Gently and slowly invert the sample cell to fully mix the sample. Be careful not to add air bubbles.

6. Put the sample cell in the sample cell holder with the triangle on the sample cell aligned with the reference mark on the sample cell holder. Close the cover.

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Measurement techniques

Measurements may be made with different operation mode settings and optional accessories.

Calibrate the instrument whenever the sample cell pathlength is changed.

Manual or automatic ranging

The manufacturer recommends that ranging be set to automatic for most measurements.

The setting can be changed at any time during sample measurement.

Push RANGE repeatedly to step the instrument from automatic ranging to manual ranging and then scroll through the manual range settings.

The Manual Range light turns on when manual ranging is selected. The Auto Range light turns on when automatic ranging is selected.

Notes:

• When manual ranging is selected, the display flashes all 9s when the sample being measured is greater than the selected range. The display flashes all 0s when the sample measured is less than the selected range.

• When automatic ranging is selected, the display flashes 9s when the sample is greater than the maximum range of the instrument.Refer to

Measure over-range samples on page 22.

• When automatic ranging is selected, the display flashes all 0s when the measurement is less than the range of the instrument or a negative value. Calibrate the instrument.

Signal averaging on or off

Signal averaging corrects for reading fluctuations that are caused by random drifting particles in the sample. When signal averaging is on, an average reading is calculated every 3 seconds and shown on the display.The last ten measurements are used to calculate the average reading.

The manufacturer recommends that signal averaging be on for most measurements.

Push UNITS AVG to turn signal averaging on or off. The UNITS AVG light turns on when signal averaging is on.

Push ENTER when signal averaging is on to erase data in the signal averaging buffer and provide an immediate update on the display as necessary. This is especially useful when measuring samples with large differences in turbidity.

Using the air purge system

The air purge system is used to keep condensation off the external surface of the sample cell when cold samples are measured.

The air purge system pushes dry air through the optical compartment to keep the outside the sample cell dry. The connection is made at the air purge fitting on the back of the instrument Figure 2 on page 8.

Use dry nitrogen or instrument grade air (ANSI MC 11.1, 1975) at no greater than 138 kPa (20 psig). The manufacturer recommends an air consumption rate of 3 to 10 SCFH (standard cubic feet/hour).

When the sample temperature is about or less than 2 °C (35 °F), use a desiccant dryer and particle filter to make sure that the dew point of the air purge is less than the sample temperature. The air dryer contains silica gel desiccant that turns pink. Replace the desiccant when it turns pink.

If only shop air is available, use a coalescing filter with an automatic drain and a dryer and particle filter to get instrument quality air. Use a coalescing filter that typically operates for greater than 2000 hours. Replace the particle filter when the air dryer is replaced.

Figure 7 and Figure 8 show the methods for connecting the two types of

air supply to the instrument.

Note: The dryer and filter are not necessary if dry nitrogen is used.

Figure 7 Instrument quality air

1 Particle filter (Balston DFU 9933-

05-BQ or equivalent)

2 Air dryer (Balston DAU 9933-

05-101 or equivalent)

3 Pressure regulator

4 Instrument air

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Figure 8 Standard shop air

1 Particle filter 5 Filter (Balston 100-12-BX or

2 Air dryer 6 Auto drain (Balston 20-105 or

3 Coalescing filter/regulator (0–

30 psig)

4 Shop air

equivalent)

7 Filter housing (Balston

FR-920-30 or equivalent)

Using a flow cell

C A U T I O N

Do not use a flow cell with flammable samples or those that contain hydrocarbons, solvents, concentrated acids or concentrated bases that may damage wetted parts of the cells. Conduct tests before use of flow cells if sample compatibility is not known.

Note: Do not use a high pressure flow cell kit with this instrument.

Use a flow cell to increase the speed, accuracy and reproducibility of measurement. The manufacturer especially recommends using a flow cell for low turbidity measurements.

Install a flow cell

1. Fully clean and assemble the flow cell, tubing and stand. Refer to

Clean a flow cell assembly on page 26 and the user instructions

provided with the flow cell.

2. Fill the flow cell and tubing with water and make sure that there are

no leaks or air bubbles.

Note: Air bubbles collect in areas that are not cleaned fully.

3. Clean the exterior surface of the flow cell with a soft, lint-free cloth to

remove water spots and fingerprints.

4. Apply a small bead of silicone oil from the top to the bottom of the

flow cell.

Note: Use only the provided silicone oil. This silicone oil has the same refractive index as the flow cell glass and masks minor glass scratches.

5. Use the oiling cloth provided to apply the oil equally to the surface of

the flow cell. Remove the excess oil. Make sure that the flow cell is almost dry.

Note: Put the oiling cloth in a plastic storage bag to keep the cloth clean.

6. Install the flow cell in the sample cell compartment.

7. Push the inlet and outlet tubes in the slots on the top of the

instrument enclosure so the sample cell cover can be installed. Refer to the user instructions.

8. Put the flow-cell light cover over the flow cell.

Note: The standard sample cell cover of the instrument does not close when the flow cell is installed.

Clean a flow cell assembly

1. Disassemble the flow cell assembly.

2. Clean the inside and outside of the glass parts with a laboratory

glass cleaning detergent. Follow with multiple rinses with distilled or demineralized water.

Note: All tubing, flow cells, and caps in the flow cell assembly can also be steam sterilized.

3. If measuring low turbidity samples, clean the inside and outside of

the glass parts with 1:1 hydrochloric acid and rinse multiple times with dilution water.

4. Fill the sample cell with distilled or demineralized water and

immediately put the caps on the sample cell.

5. Clean the inside and outside of the plastic parts and tubing with

laboratory detergent and warm water.

Note: At intervals, replace the tubing as contaminants, including microbiological growths, are difficult to remove from the inside surface of the tubing.

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6. Air dry the parts after cleaning.

Flow cell maintenance

• Keep all parts of the flow cell assembly clean.

• At intervals, replace all the tubing to make sure that the system is clean. Keep the tubing as short as possible to minimize air locking and lag time of sample flow. Locate the instrument as close to the drain as possible.

Flow cell operation

• Do not use the flow cell for samples that contain large particles that may collect and stop the sample from flowing.

• Slowly put the sample down the interior edge of the inlet reservoir to prevent mixing of the sample, which can cause air bubbles. Air bubbles create a false positive interference in a turbidity measurement.

• If bubbles collect in the flow cell, gently tap the flow cell on a soft surface to remove the bubbles. If bubbles continue to collect in the flow cell, put the glass flow cell in liquid detergent for 24 hours and then rinse fully.

• When measuring many samples of different turbidity, measure the samples in order of the cleanest (lowest turbidity) to the dirtiest (highest turbidity) to prevent contamination from one sample to the next.

• Do not use greater than the recommended maximum sample pressure of 34 kPa (5 psig).

• Keep the drain tubing below the center line of the instrument. If the whole 152 cm (60 in.) length of drain tubing is used, make sure that the end of the drain tubing is at least 46 cm (18 in.) below the center line of the instrument.

• The flow-cell cover must be in place for the LED light source to function.

Flow cell storage

• Install the reservoir cover when the system is not in use to prevent contamination of the system by airborne particles.

• For short-term storage (a few hours), flush the system with distilled or deionized water and leave the flow cell full of the flush water to minimize air locks and build up of residue on the parts.

• For long-term storage, disassemble, fully clean and air dry all parts.

Using a manual flow cell

To set the flow rate, increase the height of the collection drain assembly on the support rod to decrease the flow rate. Make sure that the bottom of the collection drain assembly is no lower than 7.5 cm (3 in.) above the support stand base.

To flush the flow cell, lower the collection drain assembly to the support stand base to flush the flow cell.

Use a cell adapter

Many different test tubes, sample cells and ampules can be used to measure samples when a cell adapter is used. Use a cell adapter when the test tube, sample cell or ampule is less than 25 mm. Refer to

Accessories on page 36 for the available cell adapters.

Use only test tubes and sample cells that are free of significant scratches. Clean and apply silicone oil to all sample cells, test tubes and ampules used with the cell adapters. Refer to Clean the sample cell on page 16.

Note: Performance specifications may be different than shown in Specifications on page 5 when test tubes, sample cells or ampules less than 25 mm are used.

Use a cell adapter when:

• Only a small quantity of sample is available.

• The sample to be measured is in an ampule that cannot be opened.

Refer to Table 3 for minimum sample sizes.

Table 3 Minimum sample sizes

Test tube size Sample

12 mm 2.5 mL

13 mm 3.5 mL

16 mm 5 mL

19 mm 7 mL

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Install a cell adapter

1. Align the tab on the cell adapter toward the front of the instrument

(Figure 9).

2. Put the cell adapter in the sample cell holder.

3. Calibrate the instrument each time the sample cell diameter is

changed. Calibrate using sample cells of the same path length as the sample cell that will be used to measure samples.

Note: If test tubes are taller than the cover for the sample cell compartment, use the tall light shield provided with the cell adapter.

Figure 9 Install a cell adapter

Connect to a printer or computer

Use the serial interface (RS232) connector on the back of the instrument to transmit data from the instrument to a printer or a serial communication port on a computer. Refer to Figure 2 on page 8.

To connect a serial printer to the instrument, use a printer cable assembly that is terminated with a standard 25-pin D connector. A serialto-parallel converter can be used to print to a parallel printer. Data is transmitted to a printer as a 39-character string plus the line feed and carriage return.

To connect a computer to the instrument, use a serial communication cable with a DB9 connector.

Note: Use of the specified cable or equivalent is mandatory for CE compliance (a shielded cable assembly must be used).

Configure the printer output

1. Push SETUP. The SETUP light turns on.

2. Select 01 using the arrow keys.

3. Push ENTER.

4. Use the arrow keys to change the value—SL Pr (slow print,

2.5 second delay) or FS Pr (fast print).

5. Push ENTER.

6. Push SETUP.

Configure the RS232 connection

Remove a cell adapter

1. Carefully pull the cell adapter up until it is half out of the sample cell

holder.

2. Slowly turn the cell adapter 90 degrees counter-clockwise.

3. Pull the cell adapter up to remove it.

N O T I C E

Do not force the cell adapter out of the instrument as serious damage can occur.

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1. Push SETUP. The SETUP light turns on.

2. Use the arrow keys to select an option:

Option Description

10 Sets the baud rate (default=1200).

11 Sets the character length (default=8).

12 Sets the stop bit (default=1).

13 Sets the parity select (default=NONE).

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3. Push ENTER.

4. Use the arrow keys to change the value.

5. Push ENTER.

6. Push SETUP.

Computer (RS232) commands

A communication program (i.e., such as Window Terminal or ProComm Plus) is recommended for computer operation of the instrument. Configure the communication program to the RS232 connection settings. Refer to Configure the RS232 connection on page 28.

Table 4 shows the RS232 command set for the instrument.

Table 4 RS232 command set

Command Description

VAL Gets the current measurement with the measurement units.

LST Gets the calibration standards and coefficients.

DAT Gets the current date.

To change the date, enter DAT=MM/DD/YY (MM=month, DD=day, YY=year), then push Enter.

TIM Gets the current time in 24-hour format.

To change the time, enter TIM=HH:MM (HH=hour, MM=minutes), then push Enter.

RMN Gets the recorder minimum value.

To change the recorder minimum value, enter RMN=XXXXX (XXXXX=a number, minimum value=0), then push Enter.

RMX Gets the recorder maximum value.

To change the recorder maximum value, enter RMX=XXXXX (XXXXX=a number, maximum value=10,000), then push Enter.

RTN Gets the recorder trim minimum value.

To change the recorder minimum value, enter RTN=XXXXX (XXXXX=a number, minimum value=200), then push Enter.

Table 4 RS232 command set (continued)

Command Description

RTX Gets the recorder trim maximum value.

To change the recorder maximum value, enter RTX=XXXX (XXXX=a number, maximum value=4800), then push Enter.

SAV Gets the signal average buffer size.

To change the signal average buffer size, enter SAV=XX (XX=a number, maximum value=15, default=10), then push Enter.

Advanced operation

Calibrate the turbidimeter with formazin standards

The instrument may be calibrated using prepared formazin standards made from 4000-NTU formazin stock solution. Refer to Accessories on page 36.

Note: Use recently prepared formazin standards to get the accuracy specifications for turbidity in Specifications on page 5.

Prepare formazin standards

For the best accuracy and long-term data comparability, use formazin stock solution from Hach to make formazin standards.

Note: As an alternative, a 4000-NTU formazin stock solution that is prepared by the user may be used to make formazin standards. Refer to Making 4000-NTU

formazin stock solution on page 32.

Prepare formazin standards immediately before calibration in an environment that is at the same ambient temperature as the instrument. Discard after use.

Refer to Table 5 for the procedures to make the recommended calibration standards.

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Table 5 Formazin standard preparation

Standard Step 1 Step 2 Step 3

20 NTU Add 100 mL of

200 NTU Add 50 mL of dilution

1000 NTU Add 50 mL of dilution

dilution water to a clean 200-mL Class A volumetric flask. Refer to Prepare

dilution water

on page 20.

water to a clean 100mL class A volumetric flask.

With a TenSette Pipet, add 1.00 mL of well-mixed 4000-NTU formazin stock solution to the 200mL flask.

With a TenSette Pipet, add 5.00 mL of well-mixed 4000-NTU formazin stock solution to the 100mL flask.

With a TenSette Pipet, add 25.00 mL of well-mixed 4000NTU formazin stock solution to the 100mL flask.

Dilute to the mark with dilution water. Stopper and mix.

A class A volumetric pipet may be used in place of a TenSette Pipet.