In New York’s freezing climate, it is necessary to shut down or “winterize” customers’ sprinkler systems to prevent damage. Special attention should be given to removing water from the backflow preventor, pipes, valves and sprinklers. Contractors must keep in mind that manual-only, gravity-fed drain methods may produce poor results and remote-control valves cannot be manually drained unless they are disassembled. Proper winterization starts with good design techniques. A poorly designed and installed system will always be difficult to maintain, so make sure the pipes, valves and sprinklers can “give” a little during frost heaves. Install quick couplers at large main line termination points for rapid water evacuation during blowout. This hastens the blowout process by not having to run small volume sprinkler zones to get rid of the bulk of main line water. Give the customer an “as-built” drawing detailing air hose points of connection and isolation valve locations for looped main lines.
Most contractors use compressed air to force water through all of the irrigation system components. Use an air compressor capable of providing 50-80 psi, and 100-160 cfm of airflow. Do not use a small “shop” compressor and try to “cough” the system clean. It is not an acceptable practice to allow the compressor to fill the holding tank and closed main line 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 control valve.
It cannot be stressed enough, the need for contractors and homeowners to wear proper eye protection when winterizing irrigation systems. When using compressed air to blow out the system, contractors must take extreme care to avoid excessive pressure that can damage valves or sprinkler pipe or cause physical injury due to flying debris. As such, do not stand near any irrigation components during air blow out. Some manufacturers do not approve the use of compressed air for winterization and will not warrant damage to their products. Here is a point-by-point procedure for proper irrigation winterization:
- Shut off the main line.
- Relieve the water pressure on the main line by activating a station at the controller. Leave the station on.
- Attach the compressor hose to the appropriate main line connection.
- Set the pressure-regulating valve on the compressor to 50 psi.
- Turn on the compressor.
- Gradually increase the flow of air until the sprinkler heads pop up.
- The amount of airflow required will be dependent upon the size and length of the pipe and the demand from the sprinklers.
- Sustained heat from the compressed air may damage pipe and other components. Do not blow any circuit more than two minutes at a time.
- Switch to another zone by advancing the controller to the next circuit and complete for all the remaining stations.
- Repeat this process a second time to evacuate any remaining pockets of water.
- Be careful with gear drive rotor zones. “Dry” running can cause damage to rotors that use water for lubrication and cooling. When there is no more mist, move on.
- Turn the compressor off first, then the controller. Don’t pressurize a “closed” main line for safety reasons.
- Remove the compressor hose and shut off the main line.
- Turn the ball valves on the backflow preventor to a 45-degree angle to prevent ponding. Attach any special “blankets” at this time.
- Turn the controller to “OFF.” Remove the common wire for an extra measure of insurance against accidental pump start activation. Leave the controller plugged in to provide protection against extreme cold and condensation. Taking the time to winterize all parts of a sprinkler system will not only protect it this coming winter, but will also extend the life of the irrigation components so they can serve for years to come.