What aspects can be taken to solve the unstable conductivity of the laboratory pure water system?

       Conductivity is very important in laboratory pure water systems and is often used to measure purification effects. When using the laboratory pure water system, the conductivity is occasionally unstable, which is a headache for many users, but as long as the reasons and judgment methods are mastered, and improvement measures are proposed, the effect will be better after use. The instability of the conductivity of the general laboratory pure water system can be summarized as the following problems:

1. Raw water changes

①If the raw water quality is unstable and fluctuates (changes in sand content, hardness, etc.), it will naturally affect the conductivity of the produced water.

②The raw water temperature and PH value are not within the reasonable range (water temperature: 5~45℃; PH value: 4~9).

2. Failure of reverse osmosis system

Fault ①: The system is consistent with the initial state, no change has occurred, and the conductivity has increased.

Solution: The RO membrane is damaged, the components are aged, the pollution is serious or the service life is exceeded, resulting in a decrease in the desalination rate. The correct treatment method is to replace the RO membrane as soon as possible. Under normal circumstances, it is recommended to replace the RO membrane once every 6 to 12 months. If the equipment has been running for more than a year, the daily cleaning work has not fallen, and the conductivity of purified water is still unstable, you should consider replacing the RO membrane.

Fault ②: After the laboratory pure water system runs for a period of time, the conductivity increases, the water production does not change, and the drainage increases.

Solution: The membrane is degraded by the oxidizing medium, and the membrane module should be replaced in time.

Fault ③: The water production volume of the equipment decreases, and the electrical conductivity increases.

Solution: In the process of daily use, the pretreatment device is not cleaned in a timely and regular manner, and the filter element is not replaced as required, resulting in the gradual reduction or even failure of the sand carbon purification and filtration effect. The pretreatment filter element should be cleaned and replaced in time.

Fault ④: When the equipment is running, the conductivity suddenly increases, and the drainage volume increases.

Solution: The leakage of the connection sealing ring of the reverse osmosis membrane module caused a sudden increase in the conductivity. At this time, the water quality of each membrane module should be tested, and the sealing ring should be replaced after finding the leaking part.

3. Other reasons

①Environmental impact

The higher the purity of the water, the stronger the ability to dissolve substances. When the purified water is exposed to the air, the O2, NH3, and CO2 in the air will quickly dissolve into it, and the conductivity will increase immediately.

②The operation and maintenance are not in place

The equipment is not used and maintained scientifically in strict accordance with the relevant requirements when the equipment is used daily and not used for a long time.

③When the equipment is turned on, the secondary conductance rises and then drops very slowly or is difficult to drop

This situation is relatively rare and generally occurs in secondary reverse osmosis. In the middle of the two stages, measures are generally taken to add NaOH to adjust the removal of CO2 in the water. The conductivity can be adjusted by adjusting the amount of NaOH added.

The above are the reasons and solutions for the unstable conductivity of the laboratory pure water system. When using the system, users need to constantly sum up experience to ensure that they are no longer helpless when encountering similar problems, so as to better use the system.