Cycles of Concentration: How to know if your VRTX is working appropriately

Cycles of Concentration: How to know if your VRTX is working appropriately

Cycles of Concentration: How to know if your VRTX is working appropriately

Water conservation is a hot topic. Most sites look at the Cycles of Concentration (COC) of the water within their cooling system as a gauge for the conservation level.  If the COC are low, then you’re wasting water. If the COC is within the operating specification, then you’re maximizing your conservation of water.

Cycles of Concentration is defined as “the number of times cooling water is re-circulated based on the ratio of the blowdown (sump or re-circulating water) salt concentration to the salt concentration in the makeup water”. The COC can also be calculated using any ion in the water or by using conductivity/Total Dissolved Solids (TDS) that measures all conductive ions in solution.  However, a VRTX unit measures the COC differently.

On the VRTX supplied Monthly Water Analysis, VRTX looks at the COC calculations of chlorides. Think of the VRTX system as a mechanical water softener.  VRTX measures the chlorides because with a VRTX treated system, it converts some of the dissolved calcium in the water to crystals. Dissolved calcium contributes to the water’s conductivity, so it wouldn’t be an accurate measure of the actual COC your system is operating within. The VRTX treatment process does not convert any of the chlorides, so that ion is used for the COC calculation on the VRTX Water Analysis report.

The VRTX calculation for COC is given:

Cycles of Concentration =    Cl BD  (tower water chloride)
ClMU  (makeup water chloride)

Here is an example of the differences in COC calculations for a given tower treated by VRTX:

Sample ID TDS
(mg/L)
Chloride
(mg/L)

Make up

318

26

Tower  sump

1431

145

COC

4.5

5.6

Using TDS to calculate the COC results is less than the COC from chloride.   This may look like a problem; however, it is also a great thing to realize.  Since a VRTX treated system’s conductivity COC is normally lower than Chlorides COC, VRTX can use this relationship to verify the operation of the VRTX treatment.

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