Start Up and Shut Down Procedures

Start-up Information
Efficient start-up of systems using DOWEX™ ion exchange resins is important to the economics and water quality of the system. Dow offers several documents to aid in efficient start-up of your system.

Preparation of resins for food processing and contact (22KB PDF)
Preparation of chromatographic resins for food processing and contact (21KB PDF)
Color Release from Cation Resins (17KB PDF)

Oil Fouling (17KB PDF)
Layered Bed Anion De-Mixing (17KB PDF)

Shut-Down Information

Used Resins
Used resins should be stored under climate controlled conditions, where feasible, to maximize the life of the resin.

Additionally, care should be taken that the resins are not exposed to air, as they will dry out and shrink. When re-hydrated, these resins are susceptible to bead breakage due to rapid re-swelling. The salt can then be removed by successive dilutions, to prevent rapid change in osmotic pressures and resulting bead breakage.

Biological growth problems can be caused by inactivity of the resin during extended storage. In order to minimize the potential for biofouling, inactive systems should be stored in a biostatic solution such as concentrated NaCl. In addition to minimizing biogrowth, the concentrated brine solution will prevent freezing. The recommended procedure for resins used for water demineralization is as follows:

  • After exhaustion and a thorough backwash, the resin is ready for lay-up.
  • Apply a 15 - 25% NaCl solution to the bed and fill the vessel so that no air is present.
  • Upon reactivation of the vessel, the resin will need to be re-hydrated by successive washes of less concentrated salt to minimize osmotic shock.
  • Prior to service, the beds must undergo a double or triple regeneration.

For mixed bed resins in condensate polishing and other ultrapure water applications, the resins should be left in a regenerated condition as follows:

  • Separate the resins and carry out a double regeneration.
  • Rinse out the regenerants and leave the resins in the rinse water.
  • Flush the resins periodically down-flow (about once per week) to remove any TOC (Total Organic Carbon) leachate.
  • Prior to start-up, rinse and regenerate as normal.


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