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Lawn, Garden & Landscaping

2008-10-01 15:56:00

Sprinkler maintenance

Question: How important is it to drain my sprinkler system?

Answer: It’s very important to avoid any potential problems. If water is left in the pipes, it could freeze and burst, causing leaks, that could be very costly next spring. There are three basic ways to winterize your sprinkler system Manual Drain Method Use when manual valves are located at the end and low points of the irrigation piping. To drain these systems, simply shut off the irrigation water supply (shut off will be located in the basement and will be either a gate/globe valve, ball valve or stop and waste valve - see drawings below) and open all the manual drain valves. Once the water has drained out of the mainline, open the drain valve or the drain cap on the stop and waste valve (whichever is used in your area) and drain all the remaining water that is between the irrigation water shut off valve and the backflow device. Open the test cocks on the backflow device. If your sprinklers have check valves you’ll need to pull up on the sprinklers to allow the water to drain out the bottom of the sprinkler body. Depending on the location of the drain valves, there could be some water left in the backflow, the piping and the sprinklers. When all the water has drained out, close all the manual drain valves. Automatic Drain Method Use when automatic drain valves are located at the end and low points of the irrigation piping. These will automatically open and drain water if the pressure in the piping is less than 10 PSI. To activate these, you shut off the irrigation water supply and activate a station to relieve the system pressure. Once the water has drained out of the mainline, open the drain valve or the drain cap on the stop and waste valve (whichever is used in your area) and drain the remaining water that is between the irrigation water shut off valve and the backflow device. Open the test cocks on the backflow device. If your sprinklers have check valves you’ll need to pull up on the sprinklers to allow the water to drain out the bottom of the sprinkler body. Depending on the location of the drain valves, there could be some water left in the backflow, the piping and in the sprinklers. In some areas you might have a combination of the manual drain system on the mainline (the pipe between the irrigation water shut off valve and the valves) and auto drain system on the lateral lines (the pipe between the valves and the sprinklers). Blow Out Method This method is required when there are no drains installed on the Irrigation system (the most common type in the Wichita area). WARNING! WEAR APPROVED SAFETY EYE PROTECTION! Extreme care must always be taken when blowing out the system with compressed air. Compressed air can cause serious injury, including serious eye injury, from flying debris. Always wear approved safety eye protection and do not stand over any irrigation components (pipes, sprinklers and valves) during air blow out. SERIOUS PERSONAL INJURY MAY RESULT IF YOU DO NOT PROCEED AS RECOMMENDED! Let me stress that its highly recommended that a qualified licensed contractor perform this type of “Winterization” method. An air compressor is required, and is attached to the mainline via a quick coupler, hose bib or other type connection, which is located after the backflow device. To start, shut off the irrigation water supply and, with the compressor valve in the closed position, attach the air compressor hose to the fitting. Activate the station on the controller that is the zone or sprinklers highest in elevation and the furthest from the compressor. Close the backflow isolation valves. Then slowly open the valve on the compressor; this should gradually introduce air into the irrigation system. The blow out pressure should remain below the maximum operating pressure specification of the lowest pressure rated component on that zone and should NEVER exceed 80 PSI. Each station/zone should be activated starting from the furthest station/zone from the compressor slowly working your way to the closest station/zone to the compressor. Each station/zone should be activated until no water can be seen exiting the heads, this should take approximately two minutes or more per station/zone. Many smaller compressors do not produce a volume of air (cfm) sufficient to evacuate all water from the typical zone in one continuous push. In this case, it is better to use two or three short cycles per station/zone than to have one long cycle. Once the station/zone is dry, you should not continue to blow air through the pipe. Since this procedure is one that can cause the most problems here are some very important tips to follow. • Blowout your sprinkler system before the first freeze hits! If this is not possible, cover the backflow device with some old towels and a bucket to prevent freeze damage until blowout occurs. • Don’t use an air compressor rated higher than 80-90 pounds per square inch (psi) capacity needed to do the job. • Make sure the air compressor you are using does not deliver compressed air at a velocity greater than 10 cubic feet per minute (cfm). A velocity higher than 10 cfm runs the risk of damaging plastic pipes because of excessive friction. • Even if your sprinkler system has a drain, don’t assume that this will be enough to protect your pipes from freezing. These pipes still need to be blown out! • BE SURE YOU HOOK UP THE AIR COMPRESSOR TO THE BLOWOUT TEE (usually a ½” or ¾” fitting) AND NOT TO THE TEST COCK ON THE BACKFLOW ASSEMBLY! • And remember when in doubt…hire a professional!