Ion Exchange Resin Testing & Analysis Services

Test your ion exchange resin to monitor and maintain your water treatment systems such as softeners, dealkalizers, condensate polishers, deionizers or demineralizer systems. You should have the resin analyzed on a yearly basis to check the quality and performance of the resin. Samples can be taken from the resin bed and sent to Res-Kem to have the resin analyzed.

Res-Kem partners with Purolite Company to perform the resin analysis. The three most common tests we see performed are:

Total Capacity

Moisture Content

Resin Bead Integrity

Other tests that can be performed are:

Iron Fouling

Organic Fouling

Ash Content of the resin

but we will explain the latter in the detail.

First, a sample of the resin bed is required, so it can be analyzed. Taking a good sample is very important to get proper results on the analysis performed. We recommend a sample be taken from various levels of the resin bed and within different areas of the bed. We suggest using a piece of PVC pipe, ½” or 1” in diameter and long enough to get down into the resin. Stick the pvc pipe all the way down the resin bed to pull up a sample. Think of a soda straw, when you place your finger on the top of the straw in soda, and pull up the straw with soda inside it. Now that we have our sample, lets look at the resin tests.

Total Capacity Test:
The total capacity of an ion exchange resin is defined as the total number of sites available for exchange per some unit weight or unit volume of resin. The capacity is expressed in terms of millequivalents per milliliter MEQ/ML for wet resin. For example, new strong acid cation resin, typically, has a total capacity spec of 2.2 MEQ/ML. A resin sample will get compared to new virgin resin for the test. Based on our experiences with Purolite, if a total capacity analysis shows more than a 20% difference compared to new resin, one should consider a resin change out. In the case of the SAC resin, a change out would be suggested if the total capacity test of the sampled resin shows a spec of 1.75 MEQ/ML or less compared to a new spec of 2.2 MEQ/ML.

Moisture Capacity Test:
The moisture content of a resin is a measure of its water holding capacity or swelling. New Cation Softening resin will usually have a water retention spec of 45-48%. Type I Strong Base Anion resin the Chloride form has a spec of about 48-54% moisture. If a resin analysis is to be done, it is important to test the moisture content of the resin sample to see if it’s within spec. An increase of the moisture content in resin is a clear indication of oxidation occurring on the resin. The resin tends to become soft, which leads to pressure drop and channeling, and will eventually affect the capacity of the resin. Going back to the softening resin spec, if we see an increase of more than 6% on the higher spec of 48%, we will throw up a red flag.

Bead Integrity Test:
Our bead integrity test is a percentage measurement of whole, cracked, & broken resin beads. For example, test results will show the following: 94-4-2. 94% would be whole, 4% would be cracked, and 2% would be broken. Broken beads usually occur over time and are a normal part of wear and tear on the resin. Usually, a thorough backwashing of the resin bed will remove broken beads and fines. If broken beads accumulate over time because they are not flushed from backwashing, and the percentage test results of broken beads are shown to be in double digits, their presence will result in channeling of the resin bed and pressure drop.

For further information:
On our resin analysis, please visit our website.

Please contact me, Mike Polito, when you have completed the Resin Analysis Request Form.

Here are the resin analyses charges.

Common Cation Ion Exchange Resin Foulants

We are often asked to help with an ion exchange system that no longer has the same run length as when it was new. Typically, this is the result of either reversible or non-reversible fouling of the cation and/or anion ion exchange resin. These are some of the common foulants:

Iron:
Clear Water Iron (ferrous iron) can be removed through a softener. As long as iron stays in the ferrous form, regenerating a softener with a salt brine solution will remove the iron off the resin. When ferrous iron becomes oxidized into ferric iron (small solid iron particles), this type of iron will coat the surface of the resin, as well as, penetrate the internal matrix of the resin bead. Two common oxidizing agents, which can be present in water during the service cycle, are chlorine and oxygen that can cause the ferrous iron to form into ferric iron.

Aluminum:
Aluminum can be found in water due to the carryover of using Alum or Aluminum Sulfate in water treatment to remove suspended solids and turbidity. Aluminum will coat the resin and penetrate inside the resin bead causing poor exchange sites and reduce capacity.

Barium:
Barium is a metal that can be removed by softening resin. If Barium precipitates into Barium Sulfate where the Sulfate is greater than two ppm and the Barium is less than one ppm, this will foul the cation resin and reduce it’s capacity.

Oil/Grease:
Oil fouling typically occurs from leaks in oil-lubricated pumps. This will coat the resin causing short service cycles and poor product water quality. Dirt particles and broken resin beds will stick to oil and grease which also causes channeling of the resin bed.

Hardness Salts (Calcium & Magnesium):
This type of fouling occurs from improper resin regeneration. In a demineralizer or deionizer using sulfuric acid regeneration, calcium sulfate can form when the sulfuric acid regenerant is at too high a concentration or at too low a flow rate. This will lead to a gradual build up of hardness ions on the surface of the resin beads and within their structure. Once this occurs, regenerating the resin becomes more difficult which causes shorter service runs and reduces the resin life.

How Do I Figure out what the problem is?
The best way is to take a representative resin sample and have it tested. Please note, this may not be cost effective on small softeners because the labor cost of taking the sample and the resin analyses cost may be more than simply replacing with new resin. If you decide to have your resin tested, please fill out our Resin Analysis Submittal Form so we can start to figure out what the problem is. After that Mike Polito will have an RMA # issued so the resin sample can be received at Res-Kem.

Dealkalizer Performance Calculations

We recently had questions about a perceived problem with a dealkalizer. This customer believed the capacity of the dealkalizer was lower than originally specified and was unhappy with its performance. The customer was regenerating this new system more often than they regenerated the older system. We reviewed the system design and operation and found the problems.

Determining the Dealkalizer Capacity:
In order for us to know how long a dealkalizer system will produce dealkalized water between regenerations, we need a complete water analysis. There are a number of factors in determining the capacity of Dealkalizer Systems. The two most important things used to determine resin capacity are: Influent TDS and Alkalinity (as a percentage of the TDS). Once these are known, the resin capacity can be determined by using established resin manufacturers' charts, or by doing calculations based on total exchangeable anions and percentages of alkalinity and chlorides.

Based on using the charts and info from Purolite and Rohm & Haas

the capacity they should be getting is approximately 2,900 grains/cu ft x 15 cu ft = 43,500 grains removal. With 50 ppm (2.93 grains/gallon) alkalinity, this equates to 14,846 gallons between regenerations.

Minimum Flow Rate:
This capacity is further based on the flow rate of the system. Ideally, the unit should run @ 2 gpm/cu ft of resin or 30 gpm. Further, the minimum flow rate to insure proper kinetics and to prevent channeling is 2 gpm/sq ft of tank surface area. In their case, with a 30" diameter fiberglass tank, which has a surface area of 4.6 sq ft, the minimum flow rate should be 9.2 gpm.

We advised the customer that their average real time flow rate is 271 gph, which is 4.5 gpm. This is well below the recommended flow rate of 9.2 gpm. At this rate, the water is definitely channeling resulting in premature alkalinity breakthrough.

Premature alkalinity breakthrough would necessitate regenerating the system more often. If the dealkalizer was being run at the design rate of 9.2 gpm it would regenerate less often.

Resin Regeneration Frequency and Resin Life:
Before this customer understood the cause of the dealkalizer problem he was concerned the dealkalizer resin had lost its original capacity. Furthermore he was concerned that regenerating the dealkalizer more often would affect the life of the resin. The answer in both cases was no. The resin was in good shape and regenerating the system more often would not be detrimental to it.

Their very old dealkalizer did not appear to regenerate as often as the new system. There could have been any number of reasons it didn't.

• Was it actually producing dealkalized water in the 5 ppm range?
• Was the resin broken down to the point where it could operate at low flows and still work?
• Is the water analysis from 2008 the same as now?

We don't know the answers to the first two questions but it's very doubtful that the analysis is the same, as water in most areas can change dramatically from summer to winter and from drought to rainy times. We asked them to check the water in the winter when there is a lot of snow and/or ice. The salt on the roads increases the TDS of the water, not to mention the alkalinity and chlorides; all of which will have a significant affect on the performance of a dealkalizer.

Solutions and Recomendations:

Adding Caustic to Salt During Regeneration Increases Resin Capacity
They may be able to increase the capacity of the dealkalizer somewhat by increasing the amount of the salt and caustic. However, it may not be worth it given the low flow rate of operation.

We don't feel making changes to the dealkalizer will enable it to produce more treated water between regenerations. If the real time flow will continue at 4.5 gpm (or less), we suggested they installation of a recirculation pump on the softener/dealkalizer system. This will insure there is enough water going through the units and prevent channeling.