Online Residual Chlorine Detector

Table of Contents

I Overview…………………………………………………………………………1

II Structural Features and Working Principle…………………………………………1

        2.1 Structural Features …………………………………………………………………1

        2.2 Working Principle …………………………………………………………………1

III Technical Parameters…………………………………………………………………1

IV Functional Characteristics………………………………………………………………2

V Installation and Electrical Connection……………………………………………………2

        5.1 Instrument Installation …………………………………………………………………2

        5.2 Electrode Installation …………………………………………………………………3

        5.3 Connection of Instrument Rear Terminal Block ……………………………………………4

        5.4 Electrical Connection …………………………………………………………………5

VI Function Key Description………………………………………………………………5

VII Detailed Operation Instructions………………………………………………………………5

        7.1 Power On ………………………………………………………………………………5

        7.2 Main Menu ……………………………………………………………………………6

        7.3 Submenu ……………………………………………………………………………6

        7.4 Parameter Description …………………………………………………………………7

        7.5 Calibration ……………………………………………………………………………8

VIII Calibration and Maintenance Menu……………………………………………………11

        8.1 Output Current Calibration ………………………………………………………11

        8.2 Test Relay Calibration ………………………………………………………11

        8.3 Change Password …………………………………………………………………12

        8.4 Output Signal Calibration ………………………………………………………12

        8.5 After-Sales Service …………………………………………………………………12

8.6 Daily Maintenance …………………………………………………………………12

IX Completeness of Supply………………………………………………………………14

I Overview

The Industrial Online Residual Chlorine Meter (hereinafter referred to as the instrument) is a water quality online monitoring instrument with a microprocessor. It is used in drinking water treatment plants, drinking water distribution networks, swimming pools, industrial wastewater, and cooling circulating water to continuously monitor and control the residual chlorine content in water.

The instrument features an LCD display; intelligent Chinese menu operation; optional current output modes; freely settable measurement range; high and low limit alarm prompts and two sets of relay control switches with adjustable hysteresis range; automatic or manual temperature compensation; automatic or manual pH compensation; multiple automatic calibration methods for the electrode; RS485/RS232 communication for connection to a computer.

Residual chlorine electrodes for various installation processes such as [flow-through type], [immersion type], [pipeline type] can be provided according to user needs.

II Structural Features and Working Principle

2.1Structural Features:

The complete measurement system mainly consists of two parts: the instrument (secondary instrument) and the residual chlorine electrode (primary sensor). The residual chlorine electrode contacts the measured water solution, and the instrument displays the residual chlorine value, pH value, temperature value, and working status of the water solution.

2.2Working Principle:

The instrument consists of signal measurement, operation, display, network communication, and panel instructions. The residual chlorine electrode contains a temperature electrode and a pH electrode. The sampled signals are amplified by the instrument amplifier into low-resistance voltage signals, which are sent to the operation unit to display the measured value.

The residual chlorine electrode uses gold (Au) as the cathode and silver (Ag) as the anode. The filling solution, i.e., the electrolyte, is 0.1M potassium chloride (KCl). It uses a permeation membrane selective for hypochlorous acid (HOCl). This membrane allows only HOCl molecules to permeate freely, while hypochlorite ions (ClO-) and chlorine cannot pass through. During measurement, a polarization voltage is applied between the anode and cathode. HOCl molecules pass through the permeation membrane and are consumed at the cathode, generating a current proportional to the hypochlorous acid concentration flowing through the electrode. The instrument detects this current and, through calculation, converts it into the hypochlorous acid concentration. Simultaneously, the pH and temperature electrodes detect the solution's pH and temperature. The instrument calculates the residual chlorine content in the water based on the detected pH and temperature.

III Technical Parameters

(1) Measurement range: Residual chlorine (configurable): 0～20.00mg/L (ppm); Temperature: 0～60℃;

(2) Resolution: Residual Chlorine: 0.001mg/L;  Temperature: 0.1℃;

(3) Automatic or manual temperature compensation range: 0～60℃ (reference temperature 25℃)

(4) pH compensation range: Manual pH compensation: 5～9pH;

(5) Response time: < 2min (90%, 20℃)

(6) Minimum flow rate for flow-through installation: 15cm³/S (maintain constant flow rate)

(7) Stability: Drift < 2%F•S per month at room temperature

(8) Isolated signal output: 0～10mA (load resistance < 1.5KΩ); 4～20mA (load resistance < 750Ω);

(9) Two sets of relay control contacts: 3A 240VAC, 6A 28VDC or 120VAC;

(10) Power supply: 220VAC±10%, 50±1Hz, power ≤3W;

          24VDC, power ≤1W (requires pre-order);  12VDC, power ≤1W (requires pre-order);

(11) Dimensions: 96×96×130mm;

(12) Installation method: Panel mounting (embedded); Cutout: 91×91mm;

(13) Wall-mounted: Waterproof wall-mounted box dimensions: 300(H)*200(W)*167(D)mm;

(14) Instrument weight: 0.6kg;

(15) Operating environment:

          Ambient temperature: -10～60℃;

          Relative humidity: Not more than 90%;

          No strong magnetic field interference around except the earth's magnetic field.

IV Functional Characteristics

⊙ Intelligence: Uses a single-chip microcomputer to measure residual chlorine value, pH value, and temperature;

⊙ Human-machine dialogue: Menu operation structure, users operate according to on-screen prompts;

⊙ Multi-parameter simultaneous display: Simultaneously displays residual chlorine value, pH value, temperature value, and working status;

⊙ Software-set output mode: Software selection of 0～10mA or 4～20mA output;

⊙ Freely settable measurement range and alarm upper/lower limits; Upper/lower limit exceedance alarm prompt;

⊙ Two sets of relay control switches with adjustable hysteresis control range;

⊙ Self-set password: Users can set or modify passwords to prevent unauthorized personnel from causing misoperation;

⊙ After-sales service: Provides users with technical support and after-sales service contact methods;

⊙ RS485/RS232 communication interface for connection to a computer.

V Installation and Electrical Connection

The instrument should be installed in a clean, dry, well-ventilated, and vibration-free place. There should be some space around the instrument to facilitate operation and maintenance. The instrument should be as close as possible to the sampling point for easy electrical connection. The distance between the instrument and the sensor should not be too far to facilitate calibration operations.

5.1 Installation: The instrument is suitable for panel embedded installation. The cutout dimensions are shown in Figure 1, 91×91mm. Insert the instrument into the square hole and fix it with the provided brackets.

5.2Electrode Installation

① Flow-through type (The diagram shows a single-electrode flow cell, which only installs the residual chlorine electrode):

② Immersion type (Suitable for high concentration measurement occasions, requires stable flow):

③ Pipeline type (Suitable for high concentration measurement occasions, requires stable flow):

④ Other methods: If a suitable installation method is not found above, please contact the manufacturer to customize a special installation method.

5.3 Instrument Rear Terminal Block Connection

Wiring Instructions:

1、AHNC Relay High Alarm Normally Closed Contact

2、AHCOM Relay High Alarm Common Contact

3、AHNO Relay High Alarm Normally Open Contact

4、ALNC Relay Low Alarm Normally Closed Contact

5、ALCOM Relay Low Alarm Common Contact

6、ALNO Relay Low Alarm Normally Open Contact

7、220VAC Live Wire/24VDC+/12VDC+ (Please note the instrument power supply)

8、Neutral Wire/24VDC－/12VDC－ (Please note the instrument power supply)

9、Electrode Terminal (Residual Chlorine Negative)

10、Electrode Terminal (PH Measurement)

11、Electrode Terminal (PH Reference, Temperature)

12、Electrode Terminal (Temperature)

13、Electrode Terminal (Residual Chlorine Positive)

14、Empty

15、Residual Chlorine Value Output Signal －

16、Residual Chlorine Value Output Signal ＋

17、～24、Empty

25、Communication ＋ (Optional function)

26、Communication － (Optional function)

5.4Electrical Connection: Connection between the instrument and the sensor electrode: The connections for power supply, output signal, relay alarm contacts, and sensor electrode to the instrument are all at the rear of the instrument. Wire according to Figure 3. The fixed cable lead length for the electrode is conventionally 5-10 meters. The terminal end has labeled tabs; insert them into the terminals with the same numbers on the rear of the instrument and tighten.

VI Function Key Description

There are 6 touch keys on the panel:   (Left),   (Right), (Up),  (Down), Exit, and Confirm, see the cover.

(Left): Move the cursor left during data input, or move the menu left;

(Right): Move the cursor right during data input, or move the menu right;

(Up): Move the menu up or increase the value;

(Down): Move the menu down or decrease the value;

Exit: Switch between the measurement screen and the menu screen, or go back to the previous menu, status, or cancel the entered data in the menu screen;

Confirm: Select a menu item, or confirm and end data input, or confirm certain statuses.

VII Detailed Operation Instructions

7.1 Power On: Before use, check all pipeline connections and electrical connections. After power is turned on, the instrument will enter the measurement state within seconds.

The main display shows the residual chlorine value, with pH value (manual pH compensation requires manual setting of the PH value), temperature value, and status as secondary displays. The status prompt line displays the following information: 1. Normal 2. High Limit Alarm 3. Low Limit Alarm

7.2Main Menu: Press the "Exit" key in the main display state to enter the main menu:

7.3Submenu: Before measurement, the "Parameters" should be set or modified according to the actual situation; otherwise, the existing set values in the instrument will be used. When the cursor is under the "Parameters" menu, press the "Confirm" key, enter the password, then press "Confirm" again to enter the submenu with multiple items. Entering this menu requires entering the correct password (initial password is 0000). After entering the menu, a flashing cursor will indicate the current parameter item. Move the cursor up or down according to the selected parameter, then press the "Confirm" key to enter that parameter item for setting or modification.

Important Tip: When entering a password or modifying numerical parameters, use the Up and Down keys to change digits "0～9", "minus sign", and "decimal point", and use the Left and Right keys to change position.

Backlight adjustment method: When the instrument displays as shown in Figure 4 (right), press and hold the "Up" key until a grid background appears. Release the "Up" key, then press the "Up" or "Down" key as needed to adjust the instrument's backlight to a suitable level.

Regarding the setting of "Filter Coefficient": The "Filter Coefficient" is used to set the signal acquisition frequency of the instrument, with a maximum of 1 and a minimum of 0.05. A larger value means faster acquisition frequency, and vice versa. Operation method: When the instrument displays the "Main Menu", press the Left "﹤" and Right "﹥" keys simultaneously, enter the instrument password to access. If the instrument's measurement values are unstable due to interference or other reasons in some environments, set the "Filter Coefficient" to 0.05 to slow down the acquisition frequency, reduce interference, and maintain stability.

7.4Parameter Description:

1) "Residual Chlorine I0" and "Residual Chlorine Slope"

These two items are used to set the zero potential of the residual chlorine electrode and the slope of the residual chlorine electrode, respectively. The data "I0" and "Residual Chlorine Slope" obtained after calibrating the residual chlorine electrode are recorded in this parameter menu.

2) "pH Measurement Method" and "Manual pH Value"

"pH Measurement Method" determines whether to use the pH electrode to actually measure the pH value of the solution or to use a manually entered pH value after measurement. Manually entering the pH value is mainly used when the water quality is relatively stable (6.5-7.5pH). In this case, the pH electrode does not need to be installed; directly set it to measure the residual chlorine value using the manual pH value, and the manual pH value can be set manually. This model residual chlorine meter uses manual pH compensation; set the manual pH value.

3) "pH Zero Potential" and "pH Slope"

These two items are used to set the zero potential of the pH electrode and the slope of the pH electrode, respectively. After the pH electrode is calibrated, these two data are recorded in this parameter menu. CL8130A type does not require setting or calibration.

4) "Alarm High Limit", "Alarm Low Limit", and "Alarm Hysteresis":

These three items are used to set the high and low limits for alarms (Alarm High Limit > Alarm Low Limit); and to set the hysteresis value for the control quantity.

5) "Output Upper Limit" and "Output Lower Limit":

These two items are used to set the range of residual chlorine values corresponding to the current output (Output Upper Limit > Output Lower Limit).

6) "Output Current": This menu item is used to set the current output mode of the instrument, either "0-10mA" or "4-20mA". The relationship between the output current and the measured residual chlorine value is:

0～10mA output mode: I=｛(D-DL)/(DH-DL)｝×10mA;

4～20mA output mode: I=4mA＋｛(D-DL)/(DH-DL)｝×16mA.

Where: I- output current value, D- currently measured residual chlorine value, DH- user-set "Output Upper Limit"; DL- user-set "Output Lower Limit".

7) "Temperature Mode" and "Manual Temperature": "Temperature Mode" is divided into "Actual" and "Manual".

"Actual" means the temperature is actually measured by the temperature sensor; "Manual" means the temperature is set manually and is unrelated to the actual solution temperature. This function is mainly used for simulation debugging to reduce the need for a resistance box. (It can also use "Manual" temperature setting if the measurement is not affected by temperature).

8) "Meter Number": Used for numbering when adding a communication interface.

7.5Calibration Instructions:

Since the zero current and electrode slope of each residual chlorine electrode are different, and as the filling solution (electrolyte) is consumed, the zero current and slope will gradually change during use, showing aging. Moreover, each time the electrolyte is added or the permeation membrane is replaced, it will also cause changes in the zero current and slope. This requires regular "calibration" to ensure measurement accuracy.

Entering this menu also requires the correct password. The initial password is 8130.

The instrument has: Zero Point Calibration, Slope Calibration.

Zero Point Calibration: Place the residual chlorine electrode in chlorine-free water to calibrate the electrode's zero point (calibrated at the factory, this step can be omitted).

Slope Calibration: Place the residual chlorine electrode in a solution with a known residual chlorine concentration or in the water sample to be measured, to calibrate the electrode's slope. Follow the on-screen prompts to perform the calibration easily and intuitively. After calibration, you can enter the "Parameters" menu to observe the calibration results.

After entering the "Calibration" menu, the screen will display:

Use the Up and Down keys to move the cursor, select the calibration content, and press "Confirm" to start. After accurate calibration, press "Exit" to return to the display interface. Calibrate the pH electrode first, then the residual chlorine electrode during calibration.

Zero Point Calibration (completed at the factory, can be omitted; if used after a long period without water, follow the steps below):

Calibrate the zero point of the residual chlorine electrode. Keep the membrane head clean. Before calibration, gently dry the water droplets at the bottom of the electrode with clean filter paper (do not wipe the electrode with filter paper to avoid damaging the electrode membrane). Place the residual chlorine electrode in chlorine-free water (e.g., distilled water, pure water, etc.). Operate the instrument, press the "Confirm" key to enter, then follow the on-screen prompts.

Slope Calibration (Important step, please read carefully):

Calibrate the slope of the residual chlorine electrode. Before calibration, place the residual chlorine electrode in a residual chlorine standard solution of known concentration (must have a stirrer). The pH electrode can also be placed in. Operate the instrument, press the "Confirm" key to enter, then follow the on-screen prompts.

If a residual chlorine standard solution cannot be prepared, install the residual chlorine electrode and pH electrode directly in the acrylic measurement flow cell, connect the water sample (ensure the water sample contains a certain amount of residual chlorine), let the instrument stabilize for about 30 minutes, then use residual chlorine test paper, a pen-type residual chlorine meter, or other measurement device to detect the actual residual chlorine value in the water sample. Input the actual residual chlorine value into the "Please enter residual chlorine concentration" step in the instrument's calibration menu, then press "Confirm" to calibrate, and finally press "Confirm" to save the calibrated data.

VIII Calibration and Maintenance Menu

8.1Output Current Calibration: This function is mainly used for simulated calibration of the output current, allowing users to check the accuracy of the instrument's output current over the entire output range. Secondly, when connected to a recorder or traditional lower computer, it can check if the recorder and lower computer are sampling correctly to troubleshoot faults. Entering this submenu will display a warning, reminding you to ensure that arbitrary changes in the output current will not cause any harm before using this function. Press the "Confirm" key to continue, and enter the current output setting screen as shown below. The screen displays the current output current. Use the Up/Down or Left/Right keys to change the current output current. Press the "Confirm" key to stop the change, or press the "Confirm" key to bring up a box to directly input the current value that needs to be calibrated. At this time, measure the output current with a multimeter; it should be the same as the displayed value or within the error range.

   Special reminder: When using this function, because the output current is arbitrarily set by the user and may change over the entire range, confirm that the regulating controller or computer connected to the output loop will not produce control outputs with adverse consequences.

8.2Test Relay Calibration:

Entering this submenu displays as shown on the previous page. This function is used to test the quality of the alarm control relay output. Press the Up key for high alarm: turn off or on; Press the Down key for low alarm: turn off or on.

When the controlled load rated current is less than the current the relay can承受, it can be connected as shown in the left figure below (power must not exceed 220V);

8.3Change Password:

After entering this submenu, first enter the "Original Password" (initial password is 0000), then enter the "New Password" and press "Confirm" to complete the user password modification. Up to a five-digit password can be set. Please remember the set password!

8.4Input Signal Calibration: This function is used by the manufacturer for simulation debugging.

8.5After-Sales Service: This menu displays the contact information of the sales agent.

8.6Quick Mastery and Daily Maintenance:

Before putting into operation, the residual chlorine electrode and instrument must be correctly calibrated! (Considering users without conditions, the instrument is generally calibrated before leaving the factory, and users can put it into use directly.) If problems occur during actual use, the instrument's failure rate is generally low. Mainly, the state of the residual chlorine electrode has changed, so it is necessary to check whether the residual chlorine electrode is in good condition. The residual chlorine electrode is also not easy to damage; the main issues are whether the membrane head (membrane) is good and whether the dedicated filling solution inside the membrane head is depleted.

I. Check the Electrode: Gently unscrew the black membrane head at the lower end of the residual chlorine electrode (the head membrane is yellow). If the filling solution is depleted, it needs to be added; if the membrane is damaged, it must be replaced. Each time after重新添加 filling solution or replacing the membrane head, calibration must be performed.顺便检查 the electrode core. After unscrewing the membrane head, you can see the center of the electrode head is gold, and the outer layer is a silver tube. After use for a period of time, oxidation and blackening may occur. The silver tube can be polished with sandpaper above 1000 grit, but the gold piece must not be擦拭. After replacing the membrane head and filling it with filling solution, gently screw on the membrane head (slightly tight is sufficient) to ensure the gold piece of the electrode core is flat against the center of the membrane and to prevent water from penetrating into the membrane head.

II. Calibration: First calibrate the pH electrode, then calibrate the residual chlorine electrode. Operate according to the instructions in the user manual and the prompts in the "Calibration" and other menus within the instrument. After calibration, the electrode data is stored in the parameter menu.

1, Calibration of the pH Electrode:

This model uses manual pH compensation.

2, Calibration of the Residual Chlorine Electrode:

Before calibration, ensure the residual chlorine electrode membrane head is installed correctly and placed in water. Connect the cable to the instrument and power on for more than 2 hours to polarize (activate) the electrode before calibration for greater accuracy.

(1) Zero Point Calibration: Place the residual chlorine electrode in distilled water or pure water (chlorine-free zero water). Operate the instrument to enter the "Zero Point Calibration" menu, press the "Confirm" key, wait for the current to stabilize, then press the "Confirm" key again, and press "Confirm" once more. The calibrated data is now stored. Then press "Exit" to return to the main display.

(2) Slope Calibration:

(2.1) Reference method for those with conditions:

Calibration equipment and materials: One small stirrer, one laboratory residual chlorine meter, one 250mL glass beaker, one micropipette, an appropriate amount of sodium hypochlorite solution, an appropriate amount of 6.86pH buffer solution.

Operation: Add 200mL of 6.86pH buffer solution to the glass beaker, place it on the stirrer (low stirring speed) and stir. Place both the residual chlorine electrode and the pH electrode into the buffer solution. Use the micropipette to add 10-30μL of sodium hypochlorite solution (residual chlorine value 0.5-1mg/L) to the buffer solution. Input the actual reading measured by the laboratory residual chlorine meter into this residual chlorine instrument. The operation method is described in the manual and the prompts in the instrument's menu.

(2.2) Simple method for those without conditions: Prepare water containing residual chlorine of about 0.5-1mg/L. Place the activated residual chlorine electrode into it. Measure the actual reading in the residual chlorine water using laboratory methods. Input the reading into this instrument. Operation method: In the instrument, enter the "Calibration" menu, move the flashing cursor to "Slope Calibration", press the "Confirm" key, wait for the current to stabilize relatively, then press the "Confirm" key again. Follow the on-screen instructions to input the data measured in the laboratory, then press the "Confirm" key to see the calibrated slope -××.××, press "Confirm" again to save the calibrated data. Press "Exit" to return to the main display. The calibration is now complete and it can be put into measurement. After correct calibration, usually no residual chlorine value can be measured in pure water, and a value can be measured in tap water, generally around 0.05～1mg/L (depending on the local tap water quality).

III. Maintenance

1. If the residual chlorine instrument measures a very large residual chlorine value in the water sample and it jumps unstable, it is generally because the state of the residual chlorine electrode has changed. At this time, check if the residual chlorine membrane head is damaged or if the filling solution is depleted and needs to be added; additionally, the pH value (acidity) of the water quality should be controlled within the range of 5～9pH. The method for checking the residual chlorine electrode is handled according to "I. Check the Electrode".

2、In the "After-Sales Service" menu, the measurement error can be modified when needed. Method: If the error between the online measurement and the data measured by the laboratory residual chlorine meter is large, it can be modified and calibrated in the instrument's "After-Sales Service". Operation method: Select the "After-Sales Service" menu, press the "Confirm" key to enter, then press the Left "﹤" and Right "﹥" keys simultaneously, enter the password "12345", move the cursor to select "Residual Chlorine Calibration", press confirm, then use the Up/Down or Left/Right keys to input the error value with "+" or "-", then confirm and exit. This input "+" "-" data must be removed during calibration! (Generally not used).

3、If the measured data jumps within the normal range, the filter coefficient inside the instrument can be changed. Operation method: Exit the main display of the instrument, see the 4 parameter menus, press the "Left, Right" keys simultaneously, enter the password 0000 and press the "Confirm" key to enter, move the cursor to "Filter Coefficient" and press the "Confirm" key to modify (input data). When the filter coefficient is 1.00, the interface display value changes quickly; the smaller the filter coefficient, the slower the change, e.g., it can be set to 0.05.

4、Online monitoring of the measured medium should maintain a certain and constant flow rate, with a minimum flow rate of 15cm³/S.

5、For the residual chlorine electrode, it is recommended to maintain it every 3 months, such as checking the electrode core (keep the head gold and silver tube bright), adding filling solution, and calibrating; replace the permeation membrane (residual chlorine membrane) every 6 months.

IX Completeness of Supply

Note: Please check the completeness of the purchased instrument before use.

Please visit our company website to inquire about other series of analytical instruments from our company.

Instrument usage tips:

1、How to retrieve a forgotten password?

Answer: Enter the after-sales service menu. When you see the manufacturer's contact information or a blank screen, press the "Left" and "Right" keys simultaneously. At this time, you need to enter the password "54321". After entering, move the cursor to the bottom row "Password" to view the current instrument password.

2、How to correct the temperature error value (this method is only for small errors; if the actual value differs greatly, you need to check whether the instrument and electrode are working properly)?

Answer: Enter the after-sales service menu. When you see the manufacturer's contact information or a blank screen, press the "Left" and "Right" keys simultaneously. At this time, you need to enter the password "54321". After entering, move the cursor to "Temperature Calibration". If the temperature value is偏小, directly input the error value; if the temperature value is偏大, first input a minus sign and then input the error value.

3、How to correct the residual chlorine error value (this method is only for small errors; if the actual value differs greatly, you need to check whether the instrument and electrode are working properly)?

Answer: Enter the after-sales service menu. When you see the manufacturer's contact information or a blank screen, press the "Left" and "Right" keys simultaneously. At this time, you need to enter the password "54321". After entering, move the cursor to "Calibration". If the residual chlorine value is偏小, directly input the error value; if the residual chlorine value is偏大, first input a minus sign and then input the error value.