Water quality management of mold cooling water

Water quality management of mold cooling water
When the hardness of the cooling water exceeds 200mg/L, the scaling rate of the waterway is significantly accelerated, and a scale layer of 1mm can reduce the heat transfer efficiency by 10% -15%.
Three indicators of water quality
Hardness, conductivity, and chloride ions are the three core indicators. Hardness reflects the tendency towards scaling, while conductivity reflects the total amount of dissolved solids.
It is recommended to control the hardness below 200mg/L, the conductivity below 500 μ S/cm, and the chloride ion below 100mg/L.
Excessive chloride ions can corrode pipelines and mold waterways, especially stainless steel parts.
The consequences of scaling
The scale layer adheres to the inner wall of the waterway, causing an increase in thermal resistance. After the heat exchange efficiency decreases, the mold temperature increases and the cooling time prolongs.
The scale layer will also reduce the effective flow area and decrease the flow rate. Flow and temperature deteriorate simultaneously, forming a vicious cycle.
After the shedding of thick scale, it may block the small aperture circuit and cause local cooling failure.
Processing method
Softened water is the most common solution. Sodium ion exchange resin can replace calcium and magnesium ions, and the hardness can be reduced to nearly zero.
Deionized water has a higher cost and lower conductivity, making it suitable for precision molds.
Medication treatment is suitable for systems with large water volumes. The combination of scale inhibitors and corrosion inhibitors requires regular concentration testing.
Maintenance of the circulatory system
Cooling towers are prone to the growth of algae and bacteria. Algae clog the pipeline, and biofilm will reduce heat transfer.
It is recommended to perform sterilization treatment once every quarter and check the filter pressure difference every month.
Xinfeng Mold will indicate recommended water quality and cleaning cycle in the waterway description of the wheel hub mold for customers to include in equipment management.
Cleaning method
Use a brush or sponge for physical cleaning, suitable for straight holes. Chemical cleaning uses weak acid circulation, suitable for complex circuits.
After chemical cleaning, it must be neutralized and rinsed until neutral. Residual acid can corrode waterways.
The cleaning cycle is usually 12 months, and 6-8 months in hard water areas. When the pressure difference increases by 30%, it should be cleaned in advance.
water quality monitoring
Portable hardness tester and conductivity meter are basic configurations with low cost.
Measure the hardness of the replenished water once a week and the conductivity of the circulating water once a month.
Data needs to be archived. Sudden changes in water quality often correspond to problems with the replenishment water source or treatment equipment.
Differential pressure monitoring of waterways
Install a differential pressure gauge on the inlet and outlet water pipes. A 30% increase in differential pressure indicates scaling or blockage. This detects problems earlier than temperature measurement.
Differential pressure data should be recorded to form a trend. Sudden increase often corresponds to changes in water quality or filter blockage.
Maintenance during downtime
If the shutdown exceeds one week, the water circuit should be emptied and dried. Residual water can breed bacteria and corrode the inner wall.
The makeup water for the cooling tower needs to be equipped with a filter, as sediment entering the waterway will accelerate blockage.
After the waterway renovation, a flow test needs to be conducted, and if the flow deviation of each circuit exceeds 15%, it needs to be rebalanced.
It is recommended to bind the water quality record with the mold number to facilitate tracing the occurrence time of scaling problems.
Frequently Asked Questions
Question: How much is the hardness control of water quality?
Answer: It is recommended to be below 200mg/L.
Q: What is the conductivity standard?
Answer: It is recommended to be below 500 μ S/cm.
Q: What are the effects of scaling?
Answer: If the heat exchange decreases by 10% -15%, the flow rate will also decrease.
Q: How often do you clean it?
Answer: Usually 12 months, 6-8 months in hard water areas.
Q: How to choose between softened water and deionized water?
Answer: Softened water is commonly used, while deionized water is used for precision molds.
Q: How often is water quality measured?
Answer: Supplement water every week and circulate water every month.
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