Application and use method of online residual chlorine monitor

- Jul 14, 2020-

Application and use method of online residual chlorine monitor

online residual chlorine monitor

1. Principle:

Residual chlorine contains dissolved chlorine (present at low pH), hypochlorous acid and hypochlorite. CL650 calculates the concentration of hypochlorite by detecting hypochlorous acid, temperature and PH value to obtain the residual chlorine value of the water sample.


2. Technical indicators:

1. Measuring range: Hypochlorous acid (HOCL): 0-10.00 mg/L, residual chlorine: 0-20.00 mg/L, PH value: 0-14pH, temperature: 0~60℃

2. Resolution: 0.001mg/L, 0.01mg/L, 0.01pH, 0.1℃ Accuracy: better than ±1% or ±0.01 mg/L, ±1% or ±0.01 mg/L, ±0.02pH, ±0.5 ℃

3. Manual/automatic PH compensation function (0-14) and temperature compensation function (0~60℃).

4. Control interface: two groups of ON/OFF relay contacts, divided into high point and low point alarm signal photoelectric isolation output.

5. Signal isolation output: photoelectric coupler isolation protection 4~20mA signal output

6. Relay: relay hysteresis can be set arbitrarily, relay load is 10A 220VAC

7. Working conditions: ambient temperature is 0~60℃, relative humidity≤90%

8. Output load: load <500Ω (0-10mA), load <750Ω (4-20mA)

9. Input impedance: ≥1×1012Ω

10. Working voltage: 220VAC±10%, 50/60Hz

12. Dimension: 96×96×115 mm

13. Hole size: 91×91mm

14. Weight: 0.9Kg


3. Common industry applications:

1. Water plant, in the process of raw water production disinfection, real-time monitoring of water quality 24 hours. Ensure the safe and effective operation of the entire tap water production system. Waterworks: 0.3~0.8 mg/L. The free residual chlorine content of the centralized feedwater factory water shall not be less than 0.3 mg/L, and the water at the end of the pipe network shall not be less than 0.03 mg/L. "Sanitary Standards for Drinking Water BG5749-2006".

2. And the secondary water supply established to compensate for the lack of pressure in the municipal water supply pipeline and to protect the water used by people living in high-rise dwellings and livelihoods. Whether the secondary water supply facilities are constructed, designed and constructed according to the regulations directly relates to the quality, pressure and safety of the secondary water supply, and is closely related to the normal and stable life of the people. Compared with the original water supply, the quality of the secondary water supply is more likely to be polluted.

3. Swimming pool. Free residual chlorine 0.3~1 mg/L "Public Places Hygiene Index and Limit Requirements" GB37488-2019. Residual chlorine has a continuous disinfection effect. Once the amount of residual chlorine exceeds the standard, it may aggravate the odor generated by phenol and other organic substances in the water, and may also produce chloroform and other organochlorines with mutagenic, teratogenic and carcinogenic effects. In order to ensure the safety of everyone when swimming, residual chlorine is a very important indicator.

online residual chlorine monitor

4. Installation:

The method of installing the residual chlorine electrode and PH electrode into the flow cell is shown on the right. If the installation method is submerged (insertion), the electrode does not have a flow measuring groove, directly connect the residual chlorine electrode and the PH electrode with a connecting rod (to prevent water from entering the electrode cable) into the water, and then fix it with a fixing bracket. Before installation, please make sure to use raw material tape (thread) to do waterproof sealing work. On-line monitoring the measured medium should keep a certain flow rate and constant, the flow rate is 15-30cm3/S.

5. Calibration of residual chlorine online monitor:

1. Calibration of PH electrode:

 ① First prepare the PH buffer solution with the PH buffer solution powder, (the prepared PH buffer can be stored in the refrigerator and the shelf life is one month.)

②Unplug the PH electrode, clean it, perform PH zero point calibration and PH slope calibration. For the specific operation, please refer to the instruction manual. PH electrode calibration does not pass. Replace the new PH electrode. If the impurity content in the water sample is too high or the water sample is too alkaline, the pH will be increased. Electrode life decay.

2. Calibration of residual chlorine electrode:

Since the zero current and electrode slope of each residual chlorine electrode are different, as the filling solution (electrolyte) is consumed, the zero current and slope will gradually change during use, resulting in aging, and each time the electrolyte or Replacing the permeable membrane will also cause changes in zero current and slope, which requires periodic "calibration" to ensure measurement accuracy. The residual chlorine electrode requires zero point calibration and slope calibration (see the instruction manual for detailed operation). Each time the electrode filling solution and membrane cap are replaced, the electrode needs to be activated in the water sample for more than 2 hours to perform the calibration operation.

online residual chlorine monitor

6. Please pay attention to the following points for the electrical maintenance of residual chlorine electrode:

1. The electrode should be cleaned regularly. The oxygen permeable membrane must not be broken during the assembly, disassembly and cleaning of the electrode.

Wipe the oxygen-permeable membrane on the electrode to avoid damaging the oxygen-permeable membrane.

2. The cable connector must be kept clean and free from moisture or water.

3. When the difference between the displayed value and the actual value of the instrument is very large, the electrolyte in the electrode may dry up and need to be refilled with electrolyte. In general, the maintenance work of replacing or adding electrolyte is performed every 6 months; when the permeable membrane is broken The replacement integral membrane head needs to be replaced. Each time the electrolyte is replaced or added or the spare integral membrane head is replaced, the electrode needs to be repolarized and calibrated. Specific steps are as follows:

Unscrew the black part of the electrode shield at the bottom of the electrode, remove the spare integrated membrane head, turn the cylinder upside down (do not let the breathable membrane touch other things), pour the original electrolyte, and install it in the integrated membrane head Then refill the electrolyte core with half full electrolyte to drain off the excess electrolyte. Tighten and ensure that the membrane is close to the head of the electrode core. After replacing the electrolyte, the polarization and calibration should be repeated. During calibration, a solution with a known concentration must be used as the reference standard for calibration.

4. Electrode polarization: After the electrode is connected to the instrument, it should be continuously energized for more than 2 hours, which is polarization. The electrode can only be calibrated after polarization.

5. When the site is out of water for a long time or the meter is not used for a long time, the electrode should be taken out in time and cleaned and put on a protective cap.

6. If the electrode fails, the electrode needs to be replaced.