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No, as long as the flow of air does not exceed 50 psi at a flow rate of 10 to 25 cubic feet per minute.

<b>Here is more on blowing lines out to winterize a system:</b>

CAUTION! WEAR PROPER EYE PROTECTION! Extreme care must be taken when blowing out the system to avoid excessive pressure which can damage valves or sprinkler pipe or cause physical injury due to flying debris. Do not stand over any irrigation components (pipes, sprinklers, and valves) during air blow out. Air pressure must not exceed 50 pounds per square inch (psi).

Description: Compressed air is used to force water through all of the irrigation system components including the mainline pipe, sprinkler control valves, lateral pipes, and out through the sprinkler heads. To obtain proper air volume, you will need to rent or buy a compressor capable of providing 10 to 25 cubic feet per minute (CFM) of air volume. Air pressure must not exceed 50 pounds per square inch (psi) during the blow out procedure. A pressure regulating valve must be used to avoid overpressurization of the system. Air volume should be high and air pressure low. This combination of high volume and low pressure will minimize the damage that can occur during the winterization process. It is very important to select the right air compressor for the job. Some small shop compressors (2 hp) may not be adequate to complete the winterization procedure properly.

If the appropriate air compressor is not available, please call an irrigation contractor. Do not try to use an air compressor with high pressure (120 psi) and low volume to evacuate water from the system. It is not an acceptable practice to allow the compressor to fill the holding tank of the compressor and the closed mainline with high pressure air, hoping the surge of excess pressure will compensate for the lack of compressor size and blow the line clean upon opening the sprinkler control valve. This is a dangerous practice that places very severe stresses on all of the components of the system. Do not run the compressor without at least one sprinkler control valve open. This lessens the chance that the system could overpressurize. It is a common misbelief that if the system can withstand 120 psi of water pressure, similar air pressure will not damage the system. This is not true! The viscosity of air is much lower than water, generating much higher stresses that can cause severe damage to the system.

<b>Here is a link to our website for more on How To Winterize Your System:</b>
http://www.sprinklerwarehouse.com/LawnCare/Winterization.asp

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