SportsTurf

October 2011

SportsTurf provides current, practical and technical content on issues relevant to sports turf managers, including facilities managers. Most readers are athletic field managers from the professional level through parks and recreation, universities.

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Irrigation&Drainage | Tom Barrett Winterizing your irrigation system A S FALL APPROACHES and temperatures drop, the water in your irrigation systems can expand as it freezes. Now is the time to start thinking about preparing your irrigation systems for winter. Since automatic irrigation systems are usually buried only about 12 inches below the surface of the soil, water left in an irrigation system in freezing climates over the winter, even a mild winter, will certainly freeze, causing dam- age to pipes, fittings, valves, and sprinklers. Damage caused by a frozen irriga- tion system can be expensive and time consuming to repair next spring. Preventing winter damage by properly winterizing the irrigation system is an important consideration now. Using compressed air to force water out of the irrigation system is the most common method of winterization. However, irrigation systems equipped with automatic or manual drain valves may not require compressed air to winterize if the piping has been installed with slope leading toward the drain valve. If you are not sure that the system was designed to drain itself com- pletely, then use compressed air. Using compressed air on an irrigation system equipped with au- tomatic or manual drain valves will not harm the components of the irrigation system when properly executed and will ensure the irrigation system is properly winterized. SELECTING AN AIR COMPRESSOR A properly sized air compressor is critical in effectively and efficiently blowing air into the irrigation system, forcing water out through the sprinklers. Air compressors are available in various sizes. The most common portable air compressor, which represents roughly 80% of the portable air compressors going into rental fleets today, is the 185 portable air compressor. A note of caution:The expanding air coming from the air compressor into the irrigation system will get hot and may melt the plastic pipe. 30 SportsTurf | October 2011 This machine is rated at 185 cfm at 100 psi at full load. You can find one through a contractor's equipment rental shop that is more than adequate to get the job done for most residential and commercial irriga- tion systems. Smaller 5 horsepower electric air compressors, although capable of deliv- ering 100 psi, are not capable of delivering enough volume of air to adequately win- terize an irrigation system. For winterizing sprinkler systems, it is the volume of air that is more important than high pressure. In fact too high of pressure will cause damage. The preferred operating pressure will be set at 40-50 psi. This is enough air pressure to evacuate the water through the sprinklers within each zone. WINTERIZING AN IRRIGATION SYSTEM WITH COMPRESSED AIR A note of caution: The expanding air coming from the air compressor into the irrigation system will get hot and may melt the plastic pipe. Carefully check the temperature of the air-hose connection at the blow-out point, and make sure to slow down or stop momentarily if it feels too hot. Cycling through each zone two or three times for short intervals will prevent too much heat buildup. Another option is to use long stretches of compressor hose laid on the ground to absorb much of the heat before it enters the sprinkler system. Those who have experience winterizing large systems will use a combination of both or try and find an air compressor that will blow cold air. They are not as common, but they do exist. DRAIN SYSTEM WINTERIZATION Although using compressed air is the most common method for winterizing an automatic irrigation system, there are two systems that do not require the technique. The first type is a system equipped with automatic drains that open when the sys- tem pressure falls below 10 psi. For these systems, it is usually only necessary to turn off the water. An irrigation system equipped with manual drain valves requires locating and www.sportsturfonline.com By

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