Controlling Scale and Dirt in Evaporative Cooling Pads

Water Distribution

Proper water distribution is the single most important way of prolonging pad life. The water will flush away dirt and contaminants which may be harmful to the pad. Areas “starved” for water will often be the first to clog or soften.

• Check the pressure in the distribution pipe. Most distribution systems consist of a perforated plastic pipe with holes directly at a splash plate. If the pressure is too low, the water will not break up at the splash plate or distribute correctly. Streaking and dry areas will occur.


• Check for adequate water flow.


• Adjust the flow until there are no dry streaks. When the pads are operating properly, they will be thoroughly wetted with a visible flow of water trickling down the flutes. Most of the water will pass over the pad and return to the sump. If there is little water running out the bottom of the pad, the dirt and minerals are not being flush properly.


• The distribution pipe must be level. If more than one pad wall is fed by the same pump they must be carefully balanced with valves. The distribution pipe operates at a relatively lower pressure. When the cover is removed to expose the pipe, notice that the water jets only a few inches into the air. If one end of the pipe is lifted, the flow at the high end decreases.


• Check for clogged holes in the distribution pipe. The simplest way to clean the holes is to install a ball valve or threaded end cap at the end of each distribution pipe. While the pump is running, open the valve and allow the water to directly flush debris from the pipe. Usually, the first signs of a blockage will be at the end of the pipe farthest from the pump.


• Never locate the holes on the bottom of the distribution pipe. If so located, the holes are guaranteed to clog with silt from the bottom of the pipe. Clean water filter often. A dirty filter will substantially restrict the water flow. Install a ball valve on the cleanout for the filter. This way the filter can be flushed without tools and without shutting off the pump.


• Make sure the pump is large enough. The pump should be sized to supply a certain amount of water at a specified pressure. Besides lifting the water from the sump to the top of the pad, there are other pressure losses in the system.


• Required water flow for various pads:
• 4" corrugated pads 0.50 GPM per linear foot,
• 6" corrugated pads 0.75 GPM per linear foot.



Download our Evaporative Cooling Maintenance Checklist