Mass balance is a relationship between the amount of chloride ions and calcium ions in a solution. The chloride ion is very soluble and will not precipitate even at extreme cooling tower conditions. Under certain conditions, the calcium ion will precipitate out of the solution and form calcium scale.
By comparing the relative amounts of these two ions in solution, one can determine whether scale is accumulating or being removed. Chardon understands the importance of this metric and works to regulate it.
Cycles of concentration are typically calculated by dividing the concentration of chlorides in the tower water by the concentration of chlorides in the make-up water. The same concept of cycles can be applied to calcium hardness: divide the calcium hardness of the tower water by the calcium hardness of the make-up water.
Mass balance is calculated by subtracting the value for chlorides from the value for calcium hardness. The formula for calculating cooling tower mass balance is as follows:
MB = CaH – Cl-
Positive mass balance values indicate that there is more calcium in the solution than would be predicted by simply cycling up. Typically, surplus calcium comes from dissolving deposits in the tower sump or on fill slats.
Negative values indicate a loss of calcium relative to the amount that there should be at the current number of cycles of concentration. This is an indication that calcium is precipitating out of solution and building scale on heat exchange surfaces.
Additionally, mass balance is a useful measurement for calculating water loss with another formula:
MB = Drift Loss + Evaporation Loss + Blowdown Loss
This other formula showcases how much water is being lost in the system, and from what process.
Chardon Labs specializes in cooling tower water treatment. Reach out today or learn more about our cooling tower services!
