Common water quality testing equipment
A pH meter is a precision instrument that measures pH and can also be used to measure electromotive force.
1. Method of use (1) The voltage and frequency of the installation 1 power supply must conform to the data specified on the instrument nameplate, and must be well grounded. Otherwise, the pointer may be unstable when measuring.
2 The instrument is equipped with a glass electrode and a calomel electrode. The bakelite cap of the glass electrode is clamped to the small clip of the electrode holder. The metal cap of the calomel electrode is clamped to the large clip of the electrode holder. The height of the two electrodes can be adjusted using the cap screws on the electrode holder.
3 The glass electrode must be immersed in distilled water for more than 24 hours before first use. It should be soaked in distilled water when it is not used.
4 The calomel electrode should be immersed in saturated potassium chloride solution before initial use, and should not be soaked in distilled water with the glass electrode. Soak in a saturated potassium chloride solution when not in use or cover the lower capillary of the calomel electrode with a rubber cap.
(2) Calibration 1 Turn the “pH-mv†switch to the pH position.
2 Turn on the power supply and the indicator light will be on and warm up for 30 minutes.
3 Remove the small beaker of distilled water and gently blot the excess water droplets onto the glass electrode with filter paper. A well-selected pH buffer solution of known pH is placed in a small beaker. Immerse the electrode. Focus on immersing the pores of the glass electrode tip and the calomel electrode in the solution. Gently shake the small beaker to average the solution contacted by the electrode.
4 Screw the range switch to 0~7 or 7~14 according to the pH of the buffer.
5 Adjust the temperature control button so that the temperature indicated by the knob is the same as the room temperature.
6 Adjust the zero point so that the pointer points at pH 7.
7 Press gently or slightly slide the reading switch to lock the switch. Adjust the positioning knob so that the pointer just points to the pH value of the gauge buffer. Release the reading switch and repeat the operation until the value is not disturbed.
8 After the correction, do not turn the positioning knob again, otherwise it needs to be re-calibrated. Remove the small beaker of the scale liquid and wash the electrode with distilled water.
(3) Measurement 1 Drain the excess water on the electrode or flush it with the solution to be tested twice, then immerse the electrode into the solution to be tested, and gently roll or shake the small beaker to make the solution contact the electrode evenly.
2 The temperature of the solution to be tested should be the same as the temperature of the scale buffer solution.
3 calibrate the zero position, press the reading switch, the value indicated by the pointer is equal to the pH of the liquid to be tested. If the pointer reading exceeds the scale when measuring within the range of pH0~7, the range switch should be placed at pH 7~14 and then measured.
4 After the measurement is completed, after the reading switch is released, the pointer must be at pH 7, otherwise it will be readjusted.
5 Close the power supply, flush the electrode, and soak as described above.
2. Matters needing attention (1) Prevent the instrument from coming into contact with humid gas. The immersion of moisture reduces the integrity of the instrument, reducing its agility, accuracy, and chaos.
(2) The glass film of the glass electrode pellet is extremely thin and is easily broken. Avoid contact with hard objects.
(3) The glass film of the glass electrode should not be stained with oil. If it is accidentally contaminated with oil, it can be washed with carbon tetrachloride or ether, then washed with alcohol, and finally washed with distilled water.
(4) No bubbles are allowed in the potassium chloride solution of the calomel electrode, and there is little crystallization to keep it saturated. If the crystals are too much and the pores are clogged, it is best to refill the new saturated potassium chloride solution.
(5) If the pointer of the acidity meter is severely shaken, the glass electrode should be replaced.
3. Reagents lightly scale purification buffer scale preparation <br> buffer pH meter used relatively chaos. Commonly used preparation methods are as follows:
(1) A pH buffer of 4.00 was weighed and 5.07 g of potassium hydrogen phthalate dried at 105 ° C for 1 hour, dissolved in distilled water, and made up to 500 ml.
(2) The pH buffer of 6.88 is weighed 3.401 g of potassium dihydrogen phosphate (KH2PO4) dried at 130 ° C for 2 hours, 8.95 g of disodium hydrogen phosphate (Na2HPO·12H2O) or anhydrous disodium hydrogen phosphate (Na2HPO4). 3.549 g, dissolved in distilled water and made up to 500 ml.
(3) Scale buffer with pH=9.18 Weigh 3.8144 g of sodium borate (Na2B4O7·10H2O) or 2.02 of anhydrous sodium borate (Na2B4O7) and dilute distilled water to make up to 100 ml.
1. Method of use (1) The voltage and frequency of the installation 1 power supply must conform to the data specified on the instrument nameplate, and must be well grounded. Otherwise, the pointer may be unstable when measuring.
2 The instrument is equipped with a glass electrode and a calomel electrode. The bakelite cap of the glass electrode is clamped to the small clip of the electrode holder. The metal cap of the calomel electrode is clamped to the large clip of the electrode holder. The height of the two electrodes can be adjusted using the cap screws on the electrode holder.
3 The glass electrode must be immersed in distilled water for more than 24 hours before first use. It should be soaked in distilled water when it is not used.
4 The calomel electrode should be immersed in saturated potassium chloride solution before initial use, and should not be soaked in distilled water with the glass electrode. Soak in a saturated potassium chloride solution when not in use or cover the lower capillary of the calomel electrode with a rubber cap.
(2) Calibration 1 Turn the “pH-mv†switch to the pH position.
2 Turn on the power supply and the indicator light will be on and warm up for 30 minutes.
3 Remove the small beaker of distilled water and gently blot the excess water droplets onto the glass electrode with filter paper. A well-selected pH buffer solution of known pH is placed in a small beaker. Immerse the electrode. Focus on immersing the pores of the glass electrode tip and the calomel electrode in the solution. Gently shake the small beaker to average the solution contacted by the electrode.
4 Screw the range switch to 0~7 or 7~14 according to the pH of the buffer.
5 Adjust the temperature control button so that the temperature indicated by the knob is the same as the room temperature.
6 Adjust the zero point so that the pointer points at pH 7.
7 Press gently or slightly slide the reading switch to lock the switch. Adjust the positioning knob so that the pointer just points to the pH value of the gauge buffer. Release the reading switch and repeat the operation until the value is not disturbed.
8 After the correction, do not turn the positioning knob again, otherwise it needs to be re-calibrated. Remove the small beaker of the scale liquid and wash the electrode with distilled water.
(3) Measurement 1 Drain the excess water on the electrode or flush it with the solution to be tested twice, then immerse the electrode into the solution to be tested, and gently roll or shake the small beaker to make the solution contact the electrode evenly.
2 The temperature of the solution to be tested should be the same as the temperature of the scale buffer solution.
3 calibrate the zero position, press the reading switch, the value indicated by the pointer is equal to the pH of the liquid to be tested. If the pointer reading exceeds the scale when measuring within the range of pH0~7, the range switch should be placed at pH 7~14 and then measured.
4 After the measurement is completed, after the reading switch is released, the pointer must be at pH 7, otherwise it will be readjusted.
5 Close the power supply, flush the electrode, and soak as described above.
2. Matters needing attention (1) Prevent the instrument from coming into contact with humid gas. The immersion of moisture reduces the integrity of the instrument, reducing its agility, accuracy, and chaos.
(2) The glass film of the glass electrode pellet is extremely thin and is easily broken. Avoid contact with hard objects.
(3) The glass film of the glass electrode should not be stained with oil. If it is accidentally contaminated with oil, it can be washed with carbon tetrachloride or ether, then washed with alcohol, and finally washed with distilled water.
(4) No bubbles are allowed in the potassium chloride solution of the calomel electrode, and there is little crystallization to keep it saturated. If the crystals are too much and the pores are clogged, it is best to refill the new saturated potassium chloride solution.
(5) If the pointer of the acidity meter is severely shaken, the glass electrode should be replaced.
3. Reagents lightly scale purification buffer scale preparation <br> buffer pH meter used relatively chaos. Commonly used preparation methods are as follows:
(1) A pH buffer of 4.00 was weighed and 5.07 g of potassium hydrogen phthalate dried at 105 ° C for 1 hour, dissolved in distilled water, and made up to 500 ml.
(2) The pH buffer of 6.88 is weighed 3.401 g of potassium dihydrogen phosphate (KH2PO4) dried at 130 ° C for 2 hours, 8.95 g of disodium hydrogen phosphate (Na2HPO·12H2O) or anhydrous disodium hydrogen phosphate (Na2HPO4). 3.549 g, dissolved in distilled water and made up to 500 ml.
(3) Scale buffer with pH=9.18 Weigh 3.8144 g of sodium borate (Na2B4O7·10H2O) or 2.02 of anhydrous sodium borate (Na2B4O7) and dilute distilled water to make up to 100 ml.
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