PH Controller Dosing Pump
The setting of Hi and Low Level of pH Value to operate Dosing Pump:
Lower Level Dosing Pump / Alarm Setting: Press REED button lower side rotate screw provided on the right side to set lower-level alarm/relay output if pH Value of solution goes down to this value relay 1 will turn ON and provide its potential-free contact as output.
Higher Level Dosing Pump / Alarm Setting: Press REED button upper side rotate screw provided on the right side to set Higher level alarm/relay output if pH Value of solution goes higher to this value relay 2 will turn ON and provide its potential-free contact as output.
The pH scale is in the range of 1 to 14. When there is a change of pH by unit 1 (for ex. pH changes from 4 to 5), it indicates the change in hydrogen ion concentration by 10 times. When there is a change of pH by 2 units it indicates that the change in hydrogen ion concentration by 100 times. Due to this relationship, the pH scale is called logarithmic.
SET High limit and Low limit of pH Value for Buzzer / Relay Operation
a) Press the SET button Upper display show HPH the higher limit to set
and lower display shows the value of HPH already set
Press UP and DN buttons to set Higher Limit
b) Press the SET button once again Upper display shows LPH the lower limit to set
and lower display shows the value of LPH already set
Press UP and DN buttons to set Lower Limit
c) Press the SET button again to Set Delay Time DELY in Minutes. It works if pH Value
goes more than HPH or less Than LPH value than Dosing will Start after this delay
for a set value of Quantity in ML, after dosing it will further wait for monitoring pH Value
before next dosing.
d) press SET button once again to set Dosing Quantity in ML
if pH Value goes higher from HPH or lowers from LPH then concerned dosing pump will
dose this set ML quantity in solution and wait for DELY time and Monitor the pH Value
of Solution if pH value not found within Set Limits ie. Between HPH and LPH limits
then after waiting time above process will repeat again and again till pH value stables
e) Press SET Button again or ENT button to save the changes
else change will remove after power OFF
2 .Auto CALIBRATION OF 4pH AND 7 pH
1. Wash the Probe in Distilled water and then Dip in a Buffer solution of 7 pH
wait till the pH value is Stable, Press the UP button, wait to calibrate
2. Wash the probe in distilled water and then Dip in a Buffer solution of 4 pH
wait till the pH value is stable, Press the DN button, wait to calibrate
3. Push SET and ENT buttons at once calibration will set to factory set value
pH Value Scale for pH meter.
While we test many experiments, it is important to check the pH of any given chemical solution. while the pH is checked by pH or litmus paper. The change in litmus paper color indicates the change in pH, it is called a visual method. For precise noting of pH, an instrument is used and it is called a pH meter. The pH meter works on the potentiometric principle.
As the acidic solution has a more positive charge (H+ ion) than the alkaline solution, and the acidic solution has greater potential to produce current than the alkaline solution. The pH meter works to measure the potential difference (voltage) of the test solution and standard or known solution and calculates the pH. Hence, it works like a Voltmeter. To complete the circuit, two electrodes are connected in order to complete the circuit. The complete circuit allows the movement of electric current.
Working Principle of pH meter:
The working of the pH meter is based on the Nernst equation. Nernst equation derives the relation between the electric voltage with ion concentration. The Nernst equation derived for H+ ion concentration is the basis of the pH meter. The working principle of the pH meter is potentiometry. The pH meter consists of glass (also called an indicator electrode) and a reference electrode. The glass electrode consists of a glass membrane, which is sensitive to the hydrogen ion concentration of the test sample solution. And the glass electrode potential varies from sample to sample. The reference electrode is standard and has constant potential. The reference electrode does not respond to the test sample solution. The pH meter measures and compares the potential difference between both glass and reference electrodes.
Using the Nernst equation, the potential difference is used to measure the hydrogen ion concentration indicating the pH of a given solution. Due to the potential difference between the two electrodes, the electron flows and generates a current. This generated current is measured by a voltmeter. The relationship between the potential difference generated current and pH has been derived. The potential difference of 1 pH is 59.16mV at 25° C and hence when there is a difference of one pH unit, there will be a change in voltage by 59.16mV. This relationship is employed in measuring the pH.
Construction of pH meter:
The pH sensor or probe of modern pH meter is a combined type, in which test and reference electrodes are placed into a glass tube-like structure. The combined electrode consists of the following parts-
design and Construction of pH meter Probe
1. Glass bulb: It is a sensor that senses the H+ ion concentration and it is made from a special type of glass and membrane. The glass bulb consists of 0.1M HCL Solution.
2. Internal electrode: this electrode is made of silver chloride.
3. Internal solution: The silver chloride electrode is dipped in a buffer solution of 0.1 mol/L KCL of pH 4 to pH 7.
4. Reference Electrode: It is also the silver chloride electrode used for reference.
5. Junction: It is made from a ceramic junction also called a diaphragm that allows the contact of sample solution and reference electrolyte. It should not disturb the electric connection between both electrodes.
6. Filling hole: It is used for refilling the electrolyte if required.
7. Electrode body: the body is from non-conductive glass or plastic material and may be coated by epoxy to prevent glass bulbs.
when the acidic solution is rich in H+ ion concentration. When the pH probe is dipped in an acidic solution, the H+ ion moves close to the glass membrane of the sensitive glass bulb (external side of the bulb). Hence Similar reaction occurs inside the bulb, which is filled with a buffer solution of neutral pH 7. This neutral buffer solution has a constant number of Hydrogen ions. The H+ ions present inside the bulb also move close to the glass membrane (internal side of the bulb). Hence, this causes the difference in the concentration of hydrogen ion or degree of hydrogen ion activity across the membrane causing a difference in the potential (voltage). When the hydrogen ion concentration inside the glass bulb is less than the outside solution (test solution), then the given solution is acidic and hence the pH is lower than 7.
When the Hydrogen ions concentration across the membrane is similar then it is called neutral pH and the pH is equal to 7. while If the concentration of hydrogen ion of inside the bulb than outside solution then the given solution is alkaline and the pH is more than 7. Hence pH meter measures the potential difference at both the electrodes and calculates the pH as per the Nernst equation.
- Range : 0.00 to 14.0 pH
- Resolution : 0.10 pH
- Tolerence : +/- 0.15 pH
- Output : No Output Display Only
- Calibration : Front Panel Screw; 4pH and 7pH Value
- Input: pH Probe any Brand BNC Connector
- Display: Seven-Segment Bright LED Display
- Operating Voltage: 220 Vac
- Size : 96 * 96 * 110
- Body: PP/ABS
Calibration 7 pH
Dip the Electrode in standard Solution of 7 pH Value, wait for 10 Seconds to stable value
rotate screw of pH-7, and set the display to 7.00
Calibration 4 pH
Dip the Electrode in standard Solution of 4 pH Value, wait for 10 Seconds to stable value
rotate screw of pH-4, and set the display to 4.00
Press SET and ENT buttons at once ph Value will reset to factory calibration
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