The swelling behavior of resin beads in a bed can be influenced by several factors, including:

 The swelling behavior of resin beads in a bed can be influenced by several factors, including:

Chemical composition: The chemical composition of the resin affects its swelling behavior. 

Polymer structure: The polymer structure of the resin affects its swelling behavior. 

Cross-linking: The degree of cross-linking in the resin affects its swelling behavior. Resins with a higher degree of cross-linking tend to swell less than those with lower cross-linking. 

Temperature: The temperature of the water affects the expansion rate of the resin beads during regeneration. 

Backwash rate: The backwash rate affects the expansion rate of the resin beads during regeneration. 

Here are some other things to know about resin beads:

Reversible swelling: Resin beads swell and contract as they exchange ionic forms. For example, strong-acid cation resins swell when they change from sodium to hydrogen. 

Dehydration: If resin beads dry out, they can crack and break. To prevent this, you can immerse the resin in a saturated saline solution. 

Bed volume: The bed volume (BV) is the amount of resin that needs to be treated.