Depending on individual circumstances and conditions, 10% cross link resin can last years longer than 8% crosslink resin.

Water softeners use ion exchange resin beads. These

are spheres made up of strands of Polystyrene which

are wrapped in a crisscross manner.

The intersections of the strands, or number of those

intersections is termed as the crosslink and is

expressed in percentage crosslink for the resin.

Divinylbenzene (DVB) is used as an agent to hold the

crosslink intersections together. The number of

crosslinks (percent crosslink) in the bead will

determine to some degree, its strength and thus

how long it will last.

The most widely used ion exchange water softener

resins are 8% crosslink resins yet some resins are

10% crosslink. Higher crosslink resins have greater

strength will last longer, particularly when softening

chlorinated water. Chlorinated water degrades the

resin by damaging the polystyrene strands or the

Divinylbenzene, eventually causing the crosslinks to

fragment. Higher crosslink means there are more

links to hold the bead together as some are

compromised by the chlorine.

Depending on individual circumstances and

conditions, 10% cross link resin can last years longer

than 8% crosslink resin. In some cases the use of

10% crosslinked versus 8% crosslinked resin can

double the years of acceptable performance or

usable life expectancy of the water softener resin.

Additionally, as with any softener resin, it is

important to note that degradation of the softener

resin happens over time, regardless of the supply be

chlorinated or not. The performance of the resin will

degrade slowly and incrementally. An appreciable

drop in performance may be noticed in as little as a

few years and during that time the performance and

efficiency of the water softener may be reduced.

Incremental decreases in softener resin performance

need to be appreciated to sustain an effective and

efficient softening system.

Consideration of the concentration of chlorine in the

water supply and identifying the appropriate ion

exchange resin can result in the resin lasting longer,

more efficient water softening, reduced salt and

water usage due to otherwise degraded or damage

resin, reduced cost of operations, and reduced

discharge or water and sodium to wastewater

treatment plants and the environment.

By Robert Jewell

The Importance of Percent Crosslink in Ion

Exchange Resin Selection

Robert has 30 years of career experience in industrial utilities. He specializes in and has extensive

experience in the operation and management of steam plants, central plants, cooling and

refrigeration systems, potable (drinking) water systems, water treatment, wastewater treatment,

and facility management.

He is an advocate of water conservation, energy conservation and protecting our environment while

also incorporating those advocacies into sustainable water and energy efficiency activities and

programs that positively impact the organization and local community by finding efficiency and

savings in existing processes and procedures through creative solutions.

Connect with Robert on Linkedin at http://www.linkedin.com/pub/bob-jewell/26/810/32a