Some towers have spray distribution systems and some gravity flow troughs and weir systems. What are their relative merits?
Gravity flow systems require to be maintained completely level. Any sagging or move from the horizontal can lead to the situation where, for example, 75% of the water flow is presented to 25% of the tower. They operate at low velocities and any suspended solids can easily settle out leading to fouling and again poor distribution of water. Most modern cooling towers incorporate spray distribution systems. They do add to the pump head, but as most will require less than 0.35 bar, it is not normally significant relative to that for the total system. They operate at higher velocities than gravity systems and hence are less prone to fouling.