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Cooling Water: Open Loop versus Closed Loop Side Chemicals
Last Updated: 09/02/2015
Can you tell me what is the difference between open circuit cooling tower and closed system cooling tower and what are the chemical treatments used for open circuit cooling towers?

Open, is typically referred to as the side open to the atmosphere. It evaporated pure H20. The closed loop side is the side that does not evaporate to the atmosphere. The open, side requires a scale and corrosion chemical. The closed loop side or chiller side requires only a corrosion inhibitor, because you are not building up the impurities.

What are the parameters which we have to consider for adding the scale inhibitor and corrosion inhibitor or what are parameters to be maintained for make up water?

Calcium and alkalinity or pH of the makeup water must be known for selecting the correct cooling tower chemical/ open loop side. Generally, if you have good city water, chemical selection is easy. If you have hard water or an odd alkaline water, selection is more complex. For example if you are in Chicago, water is fairly easy to treat on the chiller side and cooling tower side.

I mean the parameters or characteristic of make up water? And whether conductivity and alkalinity is also considered.
Calcium and pH are used to select the open loop chemical being used. Conductivity is important in regards to how often you reuse the water in the open loop side (cycles of concentration). In general conductivity is not important on chemical selection, it is important as a reference on testing. Alkalinity or pH is important for the chemical selection and open loop side.

In which industries are they used?
All industries use chemicals for the open and closed loop side.

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