DIVISION OF GRAND JUNCTION CONCRETE PIPE CO.

WINTERIZATION

THAT ALL IMPORTANT TASK FOR YOUR IRRIGATION SYSTEM!

When fall is here and winter is approaching, it is important to remember that freezing weather can mean broken pipes, fittings, valves, sprinklers and pump equipment.  That is, unless you have properly winterized your irrigation system by blowing out all the water.  This concept seems simple enough; please follow these guidelines to ensure the best possible winterization your system can receive.  This will ensure the fewest repairs and replacements possible come spring start-up.

When referring to winterization, it is important to understand why we need to winterize.  Most substances contract as they get cold and freeze, but water is different.  It will contract until it reaches 39 degrees F, then it begins to expand.  After hitting freezing point, water’s volume will expand even more; by about one-eleventh.  For example, 11 cubic feet of water, when frozen, will form about 12 cubic feet.  If this happens inside of your pipes, fittings, and other parts and pieces, serious problem and costly repairs can happen.  If the amount of water in the system is minimal, then expansion is not nearly the same problem.

Before you actually blow out the system, come up with a written procedure for your system that can be followed annually.  If you have a logical and systematic approach to blowing out the system, it will go much more quickly, smoothly, and effectively.  Keep a copy of this procedure with your “as built” drawing of the system.  When developing this procedure, keep in mind the following things:  1) Determine the water source shut off,

2) Note where air compressor tie-in is located, 3) Start with valves furthest away from where the air compressor will be connected, 4) Be sure to open each valve, one at a time,  5) Go through the series of valves in short intervals, 2-3 time

When deciding on the size of the air compressor needed, remember that what counts is:
                    HIGH VOLUME, LOW PRESSURE

A sufficient volume of air is needed to fill the pipes and push the water out through the heads.  If the amount is too little it will simply flow over the top of the water rather than pushing it out.  Use the following equation to figure out the proper volume in Cubic Feet per Minutes (CFM’s), using the Gallons Per Minute (GPM’s) for which your system is designed.              GPM divided by 7.5 gallons/CFM = CFM needed

Also keep in mind that the pressure of the compressor should not exceed that of your normal operating pressure.  Both the GPM and PSI (pressure) are noted on your design.

·        To begin blowing out the system, hook up the air compressor to a garden valve location or quick coupler at the “high point” of your system.  Be sure to remove the valve itself and attach the hose adapter and 90-degree elbow to the riser.  An adapter to go from the air compressor to the garden valve riser will be needed and can generally be found at a hardware store.

·        Slightly open at least one valve or garden valve that will remain open the entire time the system is under pressure.

·        Turn on the compressor and adjust the CFM and pressure to the appropriate amount.

·        Start opening valves one at a time, starting with those furthest from the compressor.  If working with an automatic system, cycle through all the zones using short cycles.  The cycle should last as long as it takes to make each zone “mist” through only 2-3 heads.  When this happens, it is time to move to the next zone.  Manual systems work the same way except that there is no clock to do the cycles for you.

·        Once you have gone through all of the zones, do it again to make sure the majority of the water is out of the lines.

Pumping stations must also be taken apart to eliminate water in the filters, the pump itself and the intake and discharge pipes.  Be sure to cover the pump for the winter either with a canvas tarp or by placing it indoors.  Please contact Munro Pump and Supply for further information regarding winterization of your pump.

Backflow preventers must have the water expelled from them as well.  If you have a PVB or RPA close both isolation valves located on each side of the backflow preventer.  You will then need to hook the air compressor to the blow out T located prior to the valve, forcing the water out through the blow out tube.  Replace the plug and re-hook the compressor to the downstream side of the backflow preventer to push the water from there out the rest of the system. Be sure to leave isolation valves and test cocks, half-way open.

In a cross-connect system, both of the above procedures will need to be done to assure that the water is out of both the domestic and irrigation sides of the system.

Now that the water is out of the system, there are a couple of additional things to remember:

1)      If you have a manual system, you will want to leave your valves halfway open.  Metal also contracts with freezing temperatures and fully open or fully closed valves can be damaged. 

2)      Automatic systems need to have the clock reprogrammed so that it will cycle through all the zones, for a minute, once a week during the down time of the system.  This can be done by setting the water budget to about 5%.  Also, at this time, unhook the master valve wire at the clock for systems using a pump.

While blowing out the system, note any apparent cracks, breaks or problems that need to be corrected before the spring start up.

If you have any additional questions, be sure to direct them to your local irrigation specialists.  Thank you for taking care of your irrigation investment.

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Last modified: September 12, 2007