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Conductivity Meter with mV and TDS Measuring (Auto-Hold)
Conductivity Meter with mV and TDS Measuring (Auto-Hold)

Conductivity Meter with mV and TDS Measuring (Auto-Hold)

ID: GT00YZ00ZE
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Overview

GAOTEK Conductivity Meter with mV and TDS Measuring (Auto-Hold) is designed to measure pH, mV, conductivity and TDS of the liquids with 12 optional Parameter. It has large backlit LCD with auto buffer recognition. It offers 1 to 5 points push button calibration.  It provides automatic electrode slope to remind the user about the time to replace the sensor along with linear or pure water compensation mode. The built in real-time clock complies with GLP standard.

Key Features

  • Accurate reading over the entire range with calibration due reminder to calibrate the meter regularly.
  • Auto hold function helps to freeze the reading for easy viewing and recording.
  • It has provision to manually correct the temperature deviation.
  • Two different (°C or °F) units to measure.
  • Automatic electrode shows the zero point offset and slope of the electrode.
  • Handy help messages for quick reference while working with the system.
  • 12 parameters can be preset.
  • Reset facility to bring all the parameters to factory default setting.
  • Has a memory which can hold upto 500 readings.
  • Built in clock to meet GLP standard.
  • USB interface to transfer the data to PC.

Technical Specifications

pH
Range -2.000 pH ~ 20.000 pH
Accuracy  ±0.002 pH
Resolution 0.1, 0.01, 0.001 pH, Selectable
Calibration Points 1 to 5 points
Calibration Solutions USA, NIST, DIN or User Defined
Temperature Compensation 32 °F ~ 212 °F (0 °C ~ 100 °C)
Compensation Mode Manual or Automatic
mV
Range -1999.9 mV ~ 1999.9 mV
Accuracy  ±0.2 mV
Resolution  0.1, 1 mV
Conductivity
Range  0 ~ 20.00, 200.0, 2000 µS/cm, 20.00, 200.0 mS/cm
Accuracy  ± 0.5 % F.S
Calibration Points  1 to 5 points
Calibration Solutions 10 µS/cm, 84 µS/cm,1413 µS/cm,

12.88 mS/cm,111.8 mS/cm

Temperature Compensation 32 °F ~ 212 °F (0 °C ~ 100 °C), Manual or Automatic
Temperature Coefficient 0.0  ~ 10.0 % /°C
Compensation Modes Linear or Pure Water
Cell Constant K=0.1, 1, 10 or User-defined
Normalization Temperature 68 °F (20 °C) or 77 °F (25 °C)
TDS
Range 0 ppt ~100 ppt (Max. 200 ppt, depending on factor setting)
Accuracy ±1 % F.S
TDS Factor 0.1~1.0 (Default 0.5)
Temperature
Range 32 °F ~ 221 °F (0 °C ~ 105 °C)
Accuracy ± 0.5 °C, ±0.9 °F
Resolution 32.18 °F (0.1 °C)
Calibration Points 32.18 °F (0.1 °C)
Calibration Range Measured value ± 50 °F (10 °C)
Others
Hold Function Manual or Automatic
Stability Conditions Low or High
Calibration Due 0 to 31 Days
Power Off Manual or Automatic(10,20, 30 Minutes)
Reset Function Yes
Memory Stores upto 500 datasets
Output USB communication Interface
Connector BNC, 6-pin Mini Plug
Display LCD 5.18 in x 4.33 in (130 mm × 110 mm)
Power Requirements  DC 5 V, using AC adapters, 220 V AC/50 Hz
Dimension 8.27 in x 7.40 in x 2.36 in (210 mm ×188 mm × 60 mm) (L x W x H)
Weight 3.31 lbs. (1.5 kg)

Additional Information

How it works:

Accessories:

  • pH Electrode
  • Conductivity Electrode
  • Temperature Probe
  • pH Buffer Pouches (pH4.01/7.00/10.01)
  • Conductivity Calibration Solutions (84µS/cm, 1413µS/cm, 12.88mS/cm)
  • USB Cable
  • DC5V Power Adapter

Display:

GAOTEK conductivity meter with mV and TDS measuring (Auto-Hold) has crystal clear LCD that a shows the measured values. In the display there is mode indicator and help message.

Keypad:

This meter has membrane keypad. Following are the name and symbols of various function in the keypad

Connectors:

GAOTEK conductivity meter with mV and TDS measuring (Auto-Hold) provides 5 connectors for connecting the various types of sensors. Below table shows the details of connectors.

Connecting the Electrode Holder

The meter comes with an easy-to-use holder for mounting a variety of electrodes and temperature probe. If necessary, please follow the steps below to install the electrode holder.

  1. The base of the electrode holder with an irregular round hole.

2. The electrode arm has a plastic rod.

3. Insert the plastic rod into the irregular round hole and swivel the electrode arm 90°. Electrode holder is now ready to swing into desired position.

Connecting the Sensor

Take out the applicable sensors from the packaging. Follow the steps below to place the electrode into left or right sides of the electrode arm.

For the pH Electrode:

Insert the BNC connector into the corresponding connector socket. Rotate and push the connector clockwise until it locks. After connection is completed, do not pull the sensor cord. Always make sure that the connector is clean and dry.

For the Connectivity Electrode:

Insert the 6-pin connector into corresponding socket and ensure the connector is properly connected

Preparing the pH Buffer Solutions

The instrument is packaged with three pH buffer packets required for calibration.

  • Open the pH 7.00 buffer packet, place the powder into a 250 ml volumetric flask. Pour distilled water 250 ml to scale line, mix the solution until reagent is completely dissolved.
  • Preparation of pH 4.01 and pH 10.01 standard buffer solutions are the same as above.
  • Prepared standard buffer solutions should be stored in hermetically sealed glass containers.

Prior to Use:

Remove the protective cap from the bottom of the sensor.

For the pH Electrode:

If the glass sensitive membrane on the electrode dries out, soak the electrode in 3M KCL solution or tap water for at least 15 minutes. DO NOT use distilled or deionised water, it will shorten the life of sensor.

For the connectivity Electrode:

Soak the electrode for a few minutes in tap water to remove dirt and oil stains on the electrode.

Power On/Off

  • Press MEAS key to turn on the meter, the display shows measured values, mode indicators and help messages.
  • Press and hold the MEAS key for 3 seconds, the meter will turn off.
  • If you do not press any key within the specified time period, the meter will turn off automatically.

ℹ To disable the auto-off function, please read the SETUP MENU section.

Setup Menu

GAOTEK conductivity meter with mV and TDS measuring (Auto-Hold) contains an integrated setup menu that allows you to customize each displayed option to meet measurement requirements. In the different modes, the meter will show the corresponding options. For the general options, once it is changed that will be applied to all modes.

SETTING THE DEFAULT PARAMETERS:

  1. If necessary, press MODE key until the display shows corresponding mode indicator (e.g., pH mode).

  1. Press and hold key for 3 seconds, the meter enters setup menu, the display shows selectable parameter and page number.

  1. Press orkey to scroll through menu, select the parameter you want to set.

  1. Press ENTER key to confirm, the display shows an option in the submenu.

  1. Press orkey to select the desired option.
  2. Press ENTER key to confirm, the meter returns to measurement mode. Setting is completed.

EXIT THE SETUP MENU:

During the setup mode, if you want to exit setup menu, press MEAS key, the meter will return to measurement mode immediately.

Setting the Date and Time

GAOTEK conductivity meter with mV and TDS measuring (Auto-Hold) has real time clock. This can be used to add time stamp the measured value and calibration data. Follow the below steps to set the time and date in the meter

  1. Press and hold key for 3 seconds to enter the setup menu.
  2. Press or key until the display shows “DATE” option.

3. Press ENTER key to confirm, the meter shows current year.

4. Press or key to set the year.

5. Press ENTER key to confirm, the meter shows current date and time.

6. Press or key to set the date and time.

7. Press ENTER key to confirm, the meter returns to measurement mode. Setting is completed.

Temperature Compensation

In order to get accurate measuring results, you need to enable the manual or automatic temperature compensation before measurement or calibration.

Automatic Temperature Compensation

  • Place the temperature probe into the circular hole of electrode arm.

  • Insert the connector of temperature probe into corresponding connector socket (Marked “ATC”).

  • The “ATC” indicator will show on the display, the meter is now switched to automatic temperature compensation mode.

Manual Temperature Compensation

  • DO NOT connect the temperature probe to meter.
  • Press and hold the °C key for 3 seconds to enter temperature setting mode.
  • Press or key to set the temperature value of sample.
  • Press ENTER key to confirm, the meter returns to measurement mode. Setting is completed.

ℹ In the temperature setting mode press or once to increase or decrease the value in steps of 0.1. Press and hold or keys to set increment or decrement value to 1

pH Calibration

The instrument allows up to 5 points calibration in the pH mode. The user is advised to perform at least 2 points calibration for high accuracy measurement. The meter will automatically recognize and calibrate to following standard buffer values.

USA Standard Buffer Options pH 1.68, 4.01, 7.00, 10.01, 12.45
NIST Standard Buffer Options pH 1.68, 4.01, 6.86, 9.18, 12.45
DIN Standard Buffer Options pH 1.09, 4.65, 6.79, 9.23, 12.75

If you have selected the user-defined option in the setup Menu the meter allows only 2 point calibration. Single point calibration should only be done in pH 7.00, 6.86 and 6.79. In the other values the single point calibration is not accepted.

Make sure the meter is attached with new electrode during first use. DO NOT use calibration solution after calibration because the solution contaminates the meter and eventually the accuracy of the measurement.

SINGLE POINT CALIBRATION:

  1. Make sure single point calibration in setup menu
  2. Rinse the electrode with distilled water
  3. Press CAL key the meter shows “pH7.00/CAL” or “6.86/CAL” or “6.79/CAL”

  1. Dip the electrode in any of “pH7.00/CAL” or “6.86/CAL” or “6.79/CAL” buffer solution. The tip of the electrode should be completely immersed in the buffer solution. Stir the solution gently to get homogenous solution.
  2. Press ENTER key the “calibration” indicator starts flashing. Wait for the value to stabilized and the display shows “END”. The meter returns to measurement mode automatically. Now the calibration is completed.

alibration is complete

MULTI-POINT CALIBRATION:

  1. Make sure that 2 to 5 point calibration is selected in the setup menu
  2. Rinse the electrode with distilled water
  3. Press CAL key the meter shows till the display shows “CAL2”. This prompts you to continue with second point calibration.

  1. Rinse the pH electrode with distilled water. Dip the electrode into to the next standard buffer solution with pH 4.01. The meter automatically senses the current calibration solution and begins calibrating. Calibration indicator begins flashing.

  1. Wait for the measured value to stabilize and to display “CAL3”. Now the meter is prompting you to continue with third point calibration.
  2. Repeat the step 4 until the display shows “END”. The meter returns to measurement mode automatically. Calibration is completed.

pH CALIBRATION WITH THE USER DEFINED BUFFERS:

  1. Make sure that you have selected “USER” option in the setup menu. Custom buffer solution values should be at least 1 pH unit apart from each other.

  1. Rinse the pH electrode with distilled water. Dip the electrode into the custom buffer solution. Stir the sensor gently. The meter shows the current measured value.
  2. Press ▲or▼key to increase or decrease the displayed value. Press ENTER to confirm. Now “calibration” indicator would be flashing.
  3. Wait for the measured value to be stabilized and starts showing “CAL2”. The meter is now prompting you to continue with second point calibration.
  4. Rinse the pH electrode in distilled water. Dip the electrode in next custom buffer solution.
  5. Press ▲or▼key to increase or decrease the displayed value. Press ENTER to confirm. Now “calibration” indicator would be flashing.
  6. Wait for the measured value to be stabilized and starts showing “END”. The meter automatically returns to measurement mode. Calibration is completed.

  • During the calibration process if you want to exit the calibration mode press MEAS key. The meter will return to measurement mode immediately
  • Electrode indicator shows average slope of the pH electrode after calibration. When the electrode or calibration result does not meet the measurement requirements, the indicator will disappear on the display

pH Calibration Report

This program lets you check the parameters of pH electrode for diagnostic purpose

  1. Press MR key in the pH measurement mode, the display shows “LOG/P-01”
  2. Press ▲or▼key until the meter shows “ELE/P-02”(Electrode Diagnosis)

  1. Press ENTER key to confirm, the meter shows the last calibration date(Format- mm-dd)

  1. Press▼ key, the meter shows “DFS” (Zero-point offset potential).

  1. Press▼ key again, the meter shows the slope of each pH buffer group

  1. After browsing the report, press MEAS key to exit the current mode.

ℹ If you are not calibrating the meter or the calibration is not successful press MR key, the display shows “—“

Conductivity Calibration:

GAOTEK conductivity meter with mV and TDS measuring (Auto-Hold) meter is capable of using the three types of conductivity electrodes. Before calibration or measurement, you need to select the different sensors as per your sample concentration. The below table shows available sensors and its effective measuring ranges.

Make sure that you selected all the cell constants between 0.1,1 and 10 in setup menu. If the current option is “USER”, the automatic calibration function will be disabled (Refer Setup Menu Section)

In the automatic calibration mode, the meter allows up to 5 points calibration. To ensure the higher accuracy, it is recommended that you perform 3 points calibration or select a standard value which approximately close to the sample value you are measuring. The meter automatically detect conductivity standard solutions and prompt the user to calibrate the meter. When the calibration is completed all new calibration values automatically override the existing data.

The following table shows the acceptable conductivity range of calibration solution for each measuring range

SINGLE POINT RANGE

  1. Press MODE key until meter shows Indicator

  1. Rinse the conductivity electrode with distilled water. Then rinse it with small amount of calibration solution.
  2. Press CAL key, the meters enters the calibration mode.
  3. Dip the conductivity electrode into the calibration solution, the meter automatically shows current calibration standard (e.g. 1413µS/cm)

  1. Press ENTER key to confirm. The calibration indicator begins flashing

  1. Wait for the measured value to be stabilized and the display should show “END”. The meter automatically returns to measurement mode automatically. Calibration is completed.

MULTI-POINT CALIBRATION

  1. Make sure that you have selected 2 to 5 points calibration in setup menu.
  2. Rinse the conductivity electrode with distilled water. Then rinse it with small amount of calibration solution.
  3. Press CAL key, the meters enters the calibration mode.

  1. Dip the conductivity electrode into the calibration solution, the meter automatically shows current calibration standard (e.g. 12.88mS/cm)
  2. Press ENTER key to confirm, “Calibration” indicator begins flashing.
  3. Wait for the measured value to stabilize, the display shows “CAL3”. The meter prompts you to continue with third point calibration.
  4. Repeat steps 4 to 5 until the display shows “END”. The meter returns to measurement mode automatically. Calibration is completed.

MANUAL CALIBRATION

GAOTEK conductivity meter with mV and TDS measuring (Auto-Hold) provides a quick manual calibration mode that allows user to easily calibrate the meter.

  1. Record the cell constant value on the electrode (e.g. K= 1.08)

  1. Press and hold key for 3 mins to enter into setup menu. The display shows “CELL” option

  1. Press ENTER key to confirm. The meter enters into cell constant setting mode

  1. Press ▲or▼key to select “USER” option

  1. Press ENTER key to confirm. The meter enters into User-Defined mode

  1. Press ▲or▼key to set each digit according the previous record.
  2. Press ENTER key to confirm until the setting values stop flashing. The meter returns to measurement mode automatically. Setting is completed.

 

  • During the calibration process if you want to exit the calibration then press MEAS key. The meter will return to measurement mode immediately
  • Performing the conductivity calibration will simultaneously calibrate the corresponding TDS value.

CONDUCTIVITY CALIBRATION REPORT

 

  1. This program check the calibration factor of conductivity electrode.
  2. Press MR Key in conductivity measurement mode. The display shows “LOC/P-01”
  3. Until the meter shows “ELE/P-02” (Electrode a)

  1. Press ENTER key to confirm. The meter shows the date (Format: mm-dd)

  1. Press▼ key. The meter shows calibration point and calibration factor.

  1. After the browsing press MEAS to exit the current mode.

TEMPERATURE CALIBRATION

During the measurement, when automatic temperature compensation is enabled, if the temperature reading displayed differs from that of an accurate thermometer, you need to calibrate the meter.

  1. Press and hold the °C key for 3 seconds to enter temperature calibration mode, the display shows current temperature reading.

  1. Press ▲or▼key to set the temperature value.
  2. Press ENTER key to confirm. Calibration is completed.

pH Measurement

  1. Press MODE key until the display shows indicator
  2. Rinse the electrode with distilled water to remove any impurities adhering to the probe body.
  3. Dip the electrode in sample solution and stir the sensor gently
  4. Wait for the reading to be stabilized record the measured value on the display

mV Measurement:

Press MODE key until the display shows measurement unit “mV”, the meter is now enters absolute millivolt measurement mode.

Conductivity /TDS Measurement

  1. Press MODE key until the meter shows (conductivity) or TDS indicator

  1. Rinse the electrode thoroughly with distilled water.
  2. Dip the electrode in the sample solution and stir the sensor gently.
  3. Wait for the reading to be stabilized. Record the measured value in the display.

HOLD FUNCTION

The meter contains two data hold modes. When the Auto-Hold function is enabled, the meter will automatically sense a stable endpoint reading and freeze it, “HOLD” indicator appears on the display. If the Auto-Hold function is disabled, press key, the meter will immediately freeze currently displayed value. Press the key again to resume measuring.

STORING AND RECALLING DATA FROM MEMORY

GAOTEK conductivity meter with mV and TDS measuring (Auto-Hold) allows upto 500 datasets to be stored and recalled

MEMORY INPUT

During the measurement process, press MI key to input measured value into the memory, “Memory” indicator appears on the display.

MEMORY RECALL

  1. Press MR Key in the measurement mode, the meter shows “LOC/P-01” (Data Log).

  1. Press ENTER key to confirm, the meter shows page number of the stored data.

  1. Press ▼key, the meter shows date and time of the stored data (Format: mm-dd)

  1. Press ▼key again to display the stored data

  1. After browsing, Press MEAS to exit the current mode.

COMMUNICATION

GAOTEK conductivity meter with mV and TDS measuring (Auto-Hold) provides a free Data Acquisition System that can be used to transfer data, receive the measuring values or import the data to Excel. Before using, ensure that Windows 7/8/10 operating system has been installed on your computer.

RECEIVING DATA:

  • Connect the USB cable to meter and computer. Click the DAS icon, the system will automatically scan an available communication port and show the message box

“Found a port on your computer”.

  • Click the OK button, the application starts.

  • Click the Connect button, the screen shows “Port is connected” indicate that communication between the meter and the computer has been established.
  • Click the OK button to confirm.
  • Click the Receive button, the stored data in meter will automatically send to computer.

INTERVAL RECORDING

This function helps you to record the measuring value within the specify time period.

  • Click the Interval Recording button and select a time option.
  • Click the Receive button, the measured value will automatically send to data sheet.

  • The first data need 1 minute to be shown on screen.
  • Do not press any key on meter during the Interval Recording mode, it will cause communication interruption.

GRAPH MODE:

This function helps you to view variations of the measured parameter continuously. Click the Graph button, the screen will immediately show curve graph. If you want to quit current mode, click the Back button.

CREATE THE EXCEL FILE

When the transfer is completed, click the “Save as Excel” button, the measured values in the data sheet will automatically convert to Excel file.

Warning

Once the software is closed, all received data will be lost and cannot be recovered.

pH ELECTRODE CARE AND MAINTENANCE

Since pH electrode is susceptible to dirt and contamination, clean as necessary depending on the extent and condition of use.

AFTER MEASURING:

Rinse the pH electrode in distilled water, store the electrode into the electrode storage solution.

CLEANING THE ELECTRODE

  • Salt deposits: Soak the electrode in warm tap water to dissolve deposits, then thoroughly rinse with distilled water.
  • Oil or Grease film: Wash the electrode bulb gently in some detergents and water. If necessary, using the alcohol to clean the electrode bulb, then rinse with distilled water. Place the sensor in the electrode storage solution for 30 minutes.
  • Clogged reference junction: Heat a diluted KCl solution to 60 °C to 80 °C. Place the sensing part of the electrode into the heated solution for about 10 minutes. Allow the electrode to cool in some unheated KCl solution.
  • Protein deposits: Prepare a 1% pepsin solution in 0.1M of HCL. Place the electrode in the solution for 10 minutes. Rinse the sensor with distilled water.

REACTIVATING THE ELECTRODE

If stored and cleaned properly, the electrode should be ready for immediate use. However, a dehydrated bulb may cause sluggish response. To rehydrate the bulb, immerse the electrode in a pH4.01 buffer solution for 10 to 30 minutes. If this fails, the electrode requires activation.

  • Soak the pH electrode in 0.1M HCl for 5 minutes.
  • Remove and rinse with deionised water, then place in 0.1M NaOH for 5 minutes.
  • Remove and rinse again, and soak in electrode storage solution for 30 minutes.

CONDUCTIVITY ELECTRODE CARE AND MAINTENANCE

  • Ensure that the conductivity electrode is thoroughly washed with distilled water after each use.
  • If there is a build-up of solids inside the measurement area of the cell, these should be removed very carefully with a cotton bud soaked in solvent, taking care not to touch the metal parts of the inner cell.

Troubleshooting

Optional pH Electrodes

GAOTEK conductivity meter with mV and TDS measuring (Auto-Hold) is equipped with general purpose pH electrode. If it cannot fully meet your measurement requirements, please refer to the table below to select an applicable sensor.

How to prepare the conductivity standard solutions

Place AR potassium chloride reagent in a 50mL beaker and dry in an oven for 3 to 5 hours at 105°C, then cool to room temperature in desiccators.

CALIBRATION SOLUTIONS REAGENT
84 µS/cm Accurately weigh out 42.35mg of KCL and dissolve in 1000ml deionised water
1413 µS/cm Accurately weigh out 745.9 mg of KCL and dissolve in 1000ml deionised water
12.88 µS/cm Accurately weigh out 7.45g of KCL and dissolve in 1000ml deionised water
111.8 µS/cm Accurately weigh out 74.5g of KCL and dissolve in 1000ml deionised water

Stir the solution until the reagent has thoroughly mixed.

How to calculate the temperature coefficient

To determine the temperature coefficient of sample solution use this formula:

Where:

TC=Temperature coefficient

CTA=Conductivity at Temperature A

CTB=Conductivity at Temperature B

TA=Temperature A

TB=Temperature B

  1. Press and hold the °C key for 3 seconds to enter temperature setting mode.
  2. Press ▲or▼key to set the temperature at 25°C
  3. Dip the electrode into sample solution A.
  4. Record the temperature value TA and conductivity value CTA.
  5. Repeat the steps above, dip the electrode into same sample solution B. Make sure both sample solutions have about 5oC to 10oC difference.
  6. Record the temperature value TB and conductivity value CTB.
  7. Calculate the temperature coefficient of sample solution according to the formula shown above.
  8. Enter the calculated temperature coefficient into the meter.

How to calculate the TDS conversion factor

To determine the TDS conversion factor use the following formula:

Where:

Actual TDS : value from the high purity water and precisely weighed NaCl or KCL reagent.

Actual Conductivity : the meter measured conductivity value.

For example: Dissolve 64g of potassium chloride reagent in 1L distilled water. If its conductivity value is 100mS/cm, then TDS conversion factor is 0.64.

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