Multiple deionized tanks in a row getting ready for regeneration

Understanding Deionized Water Production from Mixed Bed Tanks

In the realm of water purification systems, mixed bed tanks play a crucial role in producing high-quality deionized water. The efficiency of these tanks, however, hinges significantly on the quality of the feed water they receive. That is, the amount of deionized water produced depends on the quality of the incoming feed water.

This article provides a comprehensive breakdown of how these factors influence the output of deionized water from mixed bed tanks.


Feed Water Quality and Deionized Water Output

Mixed bed tanks remove dissolved solids from water, such as calcium, magnesium, chloride, and silica. The amount of deionized water a tank can produce directly correlates with the level of Total Dissolved Solids (TDS) in the incoming feed water. Higher levels of dissolved solids result in reduced deionized water output, whereas lower levels facilitate higher production.

Tank Size and Deionized Water Output

There are various tank sizes that turn feed water into deionized water. Here are some examples of tank sizes and how much deionized water they typically yield. Of note, the amount of deionized water produced by a tank varies based on the quality of the feed water.

  • 10-inch diameter mixed bed tank containing 1.6 cubic feet of ion exchange resin typically yields between 300 – 500 gallons of deionized water.
  • 14-inch diameter mixed bed tank containing 3.6 cubic feet of ion exchange resin typically yields between 700 – 1000 gallons of deionized water.
  • Large Flowmax mixed bed tank containing 42 cubic feet of ion exchange resin typically yields between 8,000 – 12,000 gallons of deionized water.

To learn more DI tanks, view our DI Tank User Guide.

Calculating Deionized Water ProductionGraph that shows as feed water Total Dissolved Solids (TDS) increases, the gallons of deionized water produced decreases

If you want to calculate the estimated output of a mixed bed tank based on your specific feed water conditions, you can use the following formula:

Estimated water production (gallons) = (8100×Cubic feet of resin) / (Feed TDS in parts per million/17.1)

This calculation assumes an endpoint resistivity value of 200 kilo-ohm, which corresponds to a conductivity reading of approximately five microsiemens or a TDS reading of 2.5 parts per million. This means the tank needs to be regenerated at 200 kilo-ohm.

Considerations for Optimal Performance

Several factors can influence the performance and longevity of a mixed bed tank:

  1. Feed Water Variability: Changes in feed water chemistry due to seasonal variations, droughts, or shifts in municipal water sources can significantly affect the tank’s output. Monitoring these changes is crucial for accurate production estimates.
  2. Contaminants and Impurities: High levels of turbidity, organics, or chloramines in feed water can impair the function of ion exchange resin beads, reducing their efficiency and impacting production rates.
  3. Instrumentation and Operational Parameters: Regular calibration and maintenance of quality instrumentation ensure accurate readings. Proper adjustment of operating flows is also essential to maximize the tank’s operational lifespan.

Proactive Management of Deionization Tanks Ensures Reliable Performance

While municipalities control the quality of supplied water, users can optimize deionized water production by choosing high-quality ion exchange resin beads. It is also important to maintain them appropriately through regeneration processes. By understanding the dynamics of feed water quality and operational parameters, users can ensure reliable performance from their tanks.

While we cannot dictate the feed water quality provided by cities, proactive management of mixed bed tanks ensures they can adapt effectively to varying water conditions. This helps fulfill the demand for high-quality deionized water in industrial and scientific applications.

Watch this video to learn more about the factors affecting the number of gallons a DI tank will produce.