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GAOTek PH Meter with mV (2 Point Calibration, High Accuracy)
GAOTek PH Meter with mV (2 Point Calibration, High Accuracy)

PH Meter with mV (2 Point Calibration, High Accuracy)

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Overview

GAOTek PH Meter with mV (2 Point Calibration, High Accuracy) is designed using 2 point calibration mode and has manual temperature compensation function to enhance the measurement accuracy of upto 0.05 pH. It has the electrode slope display which helps the user to decide to replace the pH electrode or not. This high performance pH meter is equipped with a white backlit LCD display that is used to show measured values and mode indicators.This device can be used in Educational applications and in Laboratory use.

Key Features

  • Manual temperature compensation improves the measurement accuracy of meter.
  • Electrode slope display helps the user to decide to replace pH electrode.
  • 2 points push-button calibration with auto-buffer recognition.
  • Easy -to-use basic pH meter is equipped with a white backlit LCD display.

Technical Specifications

pH
Range 0.00 pH ~ 14.00 pH
Resolution 0.01 pH
Accuracy ±0.05 pH
Calibration Solutions USA (pH 4.01/7.00/10.01) or NIST (pH 4.01/6.86/9.18)
Calibration Points 2 points
Compensation Mode Manual
Temperature Compensation 32 °F ~ 212 °F (0 °C ~ 100 °C)
mV
Range -1999.9 mV ~ 1999.9 mV
Resolution 1 mV
Accuracy ±10 mV
Others
Connector BNC
Power Requirements DC 9 V, using AC adapter, 220 V AC/50 Hz
Dimensions 8.26 in × 8.07 in × 2.55 in(210 mm × 205 mm × 65 mm)
Weight 3.30 lbs (1.5 kg)

Additional Information

ACCESSORIES:

  • pH Electrode
  • pH Buffer Pouches (pH 4.01/7.00/10.01)
  • DC 9 V Power Adapter

Display

The pH meter is equipped with a clear and bright LCD display that is used to show measured values and mode indicators. The following table describes the meaning of each indicator.

Keypad

The meter has a succinct membrane keypad, names and symbols describe the each function key controls.

 

KEY FUNCTION
ON Turn on the meter. Press and hold the key for 5 seconds to turn off meter.
CAL Press the key to enter calibration mode.
pH Press the key to enter pH measurement mode.
mV Press the key to enter mV measurement mode.
°C Press the key to set the temperature value.
 ◄ Press the key to increase the setting value.
ENTER Confirms the calibration or setting value.
 ► Press the key to decrease the setting value.

Connectors

The device provides 3 connectors that are located on the rear panel. Listed below are the details of these connectors.

INDEX:

CONNECTOR DESCRIPTION
ELECTRODE For connecting the pH or ORP electrode.
POWER For connecting the DC9V power adapter.

Connecting the Electrode Holder

The meter comes with an easy-to-use holder for mounting the pH electrode. If necessary, follow the steps below to install the electrode holder.

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

 

  1. The electrode arm has a plastic rod.

  1. 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.

Adjustment of Electrode Arm

After installation, if the electrode arm automatically rises or falls, you need to adjust the screws until arm locate at any position.

  1. Remove the plastic cover from the electrode arm.

  1. Use the screwdriver to tighten the screw moderately.
  2. Insert the plastic cover to previous position. Installation is completed.

Connecting the pH Electrode

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

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

Connecting the Power Adapter

  1. Before plugging in the power adapter, ensure that its voltage matches your local main voltage.
  2. Insert the power connector into corresponding connector socket (Marked “Power”), the meter is now ready for use.

Power On/Off

  1. Press ON key to turn on the meter, the display shows measured values.
  2. Press and hold the ON key for 5 seconds, the meter will turn off.

Prior to Use

  • Remove the protective cap from the bottom of the pH electrode.
  • If the glass sensitive membrane on the electrode dries out, soak the electrode in 3 M KCL solution or tap water for at least 15 minutes. Do not use distilled or deionized water, it will shorten the life of sensor.

Preparing the pH Buffer Solutions

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

  1. Open the pH7.00 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.
  2. Preparation of pH 4.01 and 10.01 standard buffer solutions are the same as above.
  3. Prepared standard buffer solutions should be stored in hermetically sealed glass containers.

Temperature Compensation

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

MANUAL TEMPERATURE COMPENSATION:

Use a high-accuracy thermometer to measure the temperature of sample.

  1. Press °C key to enter the temperature setting mode.

  1. Press ▲or▼ key to set the temperature value of the sample.
  2. Press ENTER key to confirm, the meter returns to measurement mode. Setting is completed.

pH Calibration

The pH meter can perform 2 points calibration. First calibration point must use pH 7.00 (or pH 6.86) buffer solution. If your sample belongs to acidic substances, second calibration point use the pH4.01 buffer solution, alkaline substances use the pH 10.01 (or pH 9.18) buffer solution. The meter will automatically recognize and calibrate to following standard buffer values.

  • USA Standard Buffer Options: pH4.01, 7.00, 10.01
  • NIST Standard Buffer Options: pH4.01, 6.86, 9.18

The meter must be calibrated prior to first use or new electrode replaced. To ensure accuracy, regular calibration is recommended. Do not reuse calibration solution after calibration, contaminants in solution will affect the calibration and eventually the accuracy of the measurement.

  1. Rinse the pH electrode with distilled water.
  2. Press CAL key, the meter enters calibration mode, the display shows required calibration solution (e.g., pH 7.00).

  1. Dip the pH electrode into the pH7.00 standard buffer solution, the end of the electrode must be completely immersed into the calibration solution. Stir the sensor gently.

  1. Press ENTER key, the meter begins calibration. Wait for the reading to stabilize, the displayed value will flash 3 times indicating that first calibration point is completed.

The display shows “—” indicating that the meter waits for second point calibration.

  1. Rinse the pH electrode with distilled water, dip the electrode into the pH4.01 or 10.01 standard buffer solution. Stir the sensor gently. Press ENTER key to confirm.

  1. Wait for the reading to stabilize, the displayed value will flash 3 times, the meter automatically shows electrode slope and returns to measurement mode. Calibration is completed.

EXIT THE CALIBRATION:

During the calibration process, press pH key, the meter will return to measurement mode immediately.

Electrode indicator will show average slope of the pH electrode after calibration. When the electrode or calibration result does not meet measurement requirements, the indicator will disappear on the display.

pH Measurement

  • Rinse the pH electrode with distilled water to remove any impurities adhering to the probe body.
  • Dip the electrode into the sample solution, stir the sensor gently to create a homogeneous sample.
  • Wait for the measured value to stabilize, record the reading on the display.

mV Measurement

  • In the pH measurement mode, press mV key, the meter switches to mV measurement mode.
  • Rinse the electrode thoroughly with distilled water.
  • Dip the electrode into the sample solution, stir the sensor gently.
  • Wait for the measured value to stabilize, record the reading on the display.

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:

  1. Salt deposits: Soak the electrode in warm tap water to dissolve deposits, then thoroughly rinse with distilled water.
  2. Oil or Grease film: Wash the electrode bulb gently in some detergents and water. If necessary, use the alcohol to clean the electrode bulb, then rinse with distilled water. Place the sensor in the electrode storage solution for 30 minutes.
  3. 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.
  4. Protein deposits: Prepare a pepsin solution in 0.1 M 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 pH 4.01 buffer solution for 10 to 30 minutes. If this fails, the electrode requires activation.

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

Optional pH Electrodes

The instrument is equipped with a general purpose pH electrode, if it cannot fully meet your measurement requirements, please refer to the table below to select an applicable sensor.

SAMPLE TYPE P11 P12 P13 P14 P16 P17 P18 P19 P20 P21
Agar
Beer
Blood Products
Bread, Dough
Cement
Cosmetics
Dairy Products
Education
Fats/Cream
Field Use
Fish Products
Lab Flasks
Low Ionic
Meat, Cheese
Micro Samples
Paint
Photographic
Soil
Surface
Test Tubes
Tris Buffer
Viscose Samples

How to prepare the electrode storage solution

Dissolve 22.365 grams of potassium chloride reagent (KCL) in the 100 mL distilled water, stir the solution until the solution has thoroughly mixed.

How to select the USA or NIST buffer standard

The pH meter contains two pH buffer standards that can be selected. The factory default parameter is USA standard. If you want to convert into another standard, please follow the steps below to set.

  1. Press ON key to turn on the meter.
  2. Press and hold the CAL key, then pull out the power adapter.
  3. Insert the power adapter again. Undo the CAL key after 3 seconds.
  4. Press ON key to turn on the meter. Setting is completed.

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