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    Digital pH Meter, Online Test pH/ORP of Water/Food

    5 out of 5 based on 1 reviews | Write a review
    Digital pH/ORP meter can be used with various pH electrodes or ORP electrodes to realize online testing and monitoring of pH (0~14) / ORP (-1000~1000mV) / temperature (0~100℃/32~212℉) of sewage, corrosive solution, liquid medicine, beer, drinking water, food, etc. Online pH meter can be connected to digital panel meter/VFD/PLC/recorder (4-20mA output), or connected to computer for remote monitoring and recording (RS485 communication). Digital pH meter can also be connected with alarm relays and solenoid valves to form a simple pH process control system.
    Free Shipping Worldwide
    Delivery date: 10-15days

    Digital pH meter is an intelligent industrial online pH controller for water/food pH value or ORP value testing and monitoring.

    Digital pH/ORP meter is widely used in the continuous testing and monitoring of pH, ORP and temperature in thermal power, chemical fertilizer, metallurgy, environmental protection, pharmaceutical, biochemical, food, drinking water, etc.


    • 2.4 inch LCD display
    • Good anti-interference performance
    • Manual/automatic temperature compensation
    • User settings: Buzzer, LCD backlight, password, pH/ORP electrode, manual/automatic temperature compensation, pH/ORP calibration, pH/ORP modification, pH/ORP high/low alarm, output signal 4-20mA and RS485, etc.
    • Internal industrial watchdog insures pH meter don't crash.


    Model ATO-PHCR-PH4
    Weight 1kg
    Dimension 96*96*112mm (H*W*D) with hole size 93*93mm
    Measuring range pH: 0~14pH, ORP: -1000~1000mV (-2000~2000mV need customization)
    Accuracy ±0.02pH, ±1mV
    Resolution ±0.01pH, ±1mV
    Stability ≤0.02pH/24h, ≤3mV/24h
    Input impedance ≥10^12Ω
    Temperature range 0~100℃ (NTC 10K, accuracy: ±0.5℃)
    Temperature compensation 0~100℃ manual/automatic
    Output signal * Isolated 4-20mA signal (error: ±0.1%, under maximum loop resistance 750Ω)
    Communication function * RS485 with standard MODBUS-RTU (Now RS485 software is free.)
    Power supply * AC 220V±10%, 50Hz/60Hz
    AC 110V±10%, 50Hz/60Hz
    DC 24V
    Alarm relay 2 alarm relays: AC 250V/3A
    Function: high alarm, low alarm

    The pH meter and pH/ORP electrode selection:

    pH meter pH/ORP electrode Industry Temperature range Advantage
    ATO-PHCR-PH4 Combination pH electrode Sewage disposal 0-60℃ (32-140℉) Combination electrode has automatic temperature compensation function, suitable for occasions with large temperature fluctuations.
    Pure water pH electrode Drinking water 0-60℃ (32-140℉) The pH calomel electrode can be used in strong acid or alkali.
    PTFE pH electrode Chemical 0-60℃ (32-140℉) The electrode shell is made of PTFE, suitable for corrosive solution (strong acid or alkali), has longer life in harsh environments.
    pH glass electrode Sewage disposal / food 0-95℃ (32-203℉) Direct lead, double-layer glasses.
    Desulfurization pH electrode Desulfurization 0-60℃ (32-140℉) Flat electrode, strong anti-pollution ability and longer life
    High temperature/sterilization pH electrode Food 0-130℃ (32-266℉) The electrode can withstand high temperature of 0-130℃, suitable for occasions of high temperature sterilization in pharmaceutical factories, breweries, etc.
    High pressure/accuracy pH electrode Laboratory 0-80℃ (32-176℉) Its linearity and accuracy are higher than all above electrodes.

    Wiring diagram:
    Digital ph meter wiring diagram
    Definition of the ports:
    Digital pH meter ports definition

    • INPUT: Measuring terminal of the electrode
    • REF: Reference terminal of the electrode
    • NC: Undefined
    • TEMP2: Temperature compensation terminal 2
    • TEMP1: Temperature compensation terminal 1
    • RS485 (A+): RS485 communication interface A+
    • RS485 (B-): RS485 communication interface B-
    • 4-20mA (+): 4-20mA output terminal +
    • 4-20mA (-): 4-20mA output terminal -
    • AC 220V/110V (L) or DC 24V (-): AC 220V/110V live wire or DC 24V (-)
    • AC 220V/110V (N) or DC 24V (+): AC 220V/110V neutral wire or DC 24V (+)
    • LO (AL): Low alarm
    • HI (AH): High alarm

    RS485 communication data and register address as follows:

    Address Data type Function code Explanation Access right
    0x0000 unsigned short 0x03 pH value (default in two decimals) Read only
    0x0001 unsigned short 0x03 Temperature value (default in one decimals) Read only
    0x0002 short 0x03 ORP value (signed integer) Read only

    Tips: How to control the pH value to be 6-9 with a pH meter?
    The pH electrode with submersible installation is submerged in the alkali pool to test the pH value. The lower limit alarm relay of the pH meter is connected to a solenoid valve (normally closed solenoid valve).
    First, set the lower alarm value to be 6 for closed and 7 for open, when the pH value is below 6, the alarm relay is closed and the dosing pump works to add lye to the pool. When pH value in the pool reaches 7, the alarm relay is closed, and the dosing pump stops to add lye.
    Second, set the upper alarm value to be 9 for closed and 8 for open, when the pH value is above 9, the alarm relay is closed and the dosing pump works to add acid liquor to the pool. When pH value in the pool reaches 8, the alarm relay is close and the dosing pump stops to add acid liquor.
    Through the alarm return difference, pH value will be controlled between 6 and 9.

    Existing reviews of Digital pH Meter, Online Test pH/ORP of Water/Food
    The measured data of pH meter is very close to the theoretical value.
    Digital pH meter is very practical and convenient to carry to other place. The pH meter has high accuracy. The measured data is very close to the theoretical value.
    From: Kraus | Date: 20/10/2018
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