solution may result from greater cooling tower efficiency. However the higher the TDS concentration, the greater the risk of scale, biological growth and corrosion. The amount of blow-down is primarily designated by measuring by the electrical conductivity of the circulating water. Biological growth, scaling and corrosion can be prevented by chemicals (respectively, biocide, sulfuric acid, corrosion inhibitor). On the other hand, the only practical way to decrease the electrical conductivity is by increasing the amount of blow-down discharge and subsequently increasing the amount of clean make-up water. Zero bleed for cooling towers, also called zero blow-down for cooling towers, is a process for significantly reducing the need for bleeding water with residual solids from the system by enabling the water to hold more solids in solution. Make-up — The water that must be added to the circulating water system in order to compensate for water losses such as evaporation, drift loss, blow-out, blow-down, etc. Noise — Sound energy emitted by a cooling tower and heard (recorded) at a given distance and direction. The sound is generated by the impact of falling water, by the movement of air by fans, the fan blades moving in the structure, vibration of the structure, and the motors, gearboxes or drive belts. Approach — The approach is the difference in temperature between the cooled-water temperature and the entering-air wet bulb temperature (twb). Since the cooling towers are based on the principles of evaporative cooling, the maximum cooling tower efficiency depends on the wet bulb temperature of the air. The wet-bulb temperature is a type of temperature measurement that reflects the physical properties of a system with a mixture of a gas and a vapor, usually air and water vapor Range — The range is the temperature difference between the warm water inlet and cooled water exit. Fill — Inside the tower, fills are added to increase contact surface as well as contact time between air and water, to provide better heat transfer. The efficiency of the tower depends on the selection and amount of fill. There are two types of fills that may be used: Film type fill (causes water to spread into a thin film) Splash type fill (breaks up falling stream of water and interrupts its vertical progress) Full-Flow Filtration — Full-flow filtration continuously strains particulates out of the entire system flow. For example, in a 100-ton system, the flow rate would be