The most common signals sent out from a transducer are electrical current or voltage and pneumatic pressure. These signals are easily translated by controllers. Visual measuring devices like liquid bulb thermometers are not able to be used in automatic control systems because there are no electrical or pneumatic signals.

However, when some other component is added to it to enable it to give a corresponding signal, then measuring unit becomes a transducer.

A transducer is a device to convert a signal (representing a physical quantity) of one form into a corresponding signal of another form, retaining amplitude variations of energy being converted.

After some time of circulating through cooling towers, water becomes more and more concentrated with dissolved salts in water. The concentrated water has to be drained off and fresh new water added into system to make it less saline.

However, when fresh water is added, it will not have any passivation chemicals to protect piping and component condenser parts from corrosion. So chemicals are added to protect piping and machinery.

For cooling tower water, chemical used serve 2 basic functions - a corrosion inhibitor and a biocide.

The corrosion inhibitor is for preventing corrosion in piping and related parts. The biocide is to prevent growth of algae, bacteria and other micro organisms.

Every water treatment chemical company has its own formula and special concortions. A typical corrosion inhibitor may contain about 1 - 10% Potassium Hydroxide or similar alkali. This is then further diluted when mixed with water in cooling tower. Being an alkali, it will neutralize any acids found in water that can cause corrosion to occur.