As winter approaches, many of us are preparing for this cold, cold season – getting the warm clothes out of storage, changing tires to winter tires, and enjoying the crisp air a moment before it starts being so cold it hurts your lungs.
And just like our clothes, our homes, and our cars, we need to prepare our irrigation system, and particularly our filtration system for freezing temperatures.
Cold Water & Filters
So why is the combination of cold temperatures, water, and filters dangerous and requires special attention every year?
To answer that question, we need to first understand that water molecules expand in the cold, or more accurately, when its temperature drops below 4°C (39.2°F). When it freezes, water volume expands by approximately 9%.
Now, think of what happens if your irrigation system is filled with water, and the temperature drops fast. As it reaches freezing temperatures, water in your pipes, taps, filters, and everywhere else – expands. The already-pressurized system is put under significant strain, and the water is looking to exit through the weakest spots in the system.
Inside the filter, as the water solidifies, it moves around, and can eventually bend and buckle the metal screen, damage the polymer discs, deform plastic and even metal parts, or cause other malfunctions. During the cold season, you probably won’t even notice the issue until temperatures rise and you try running your system again.
What Can You Do?
Whether you have an automatic filter, semi-automatic, or manual, there are steps you should take to protect your system and prevent unpleasant surprises after the cold season’s over.
- Clean the screen element by one of the two methods:
- Closing the filter’s downstream valve(s) and manually initiating three power-flush cycles.
- Removing the screen element to wash it with a high-pressure washer to remove debris
- The screen element has to be inspected visually by looking through it into a source of light to verify its complete cleanliness. Please note that any residual contamination could dry and adhere to the screen, preventing the passage of water during future use. After the inspection is complete, reassemble the screen into the drained filter
- Drain the filter body completely to prevent damage to its components
- Center the limit switch contactor plate between the limit switches by disconnecting the control board from its power source before the limit switch disc reaches the switch (on the EBS and SAF models)
- Disassemble the 3/4” control filter. Clean and drain the feed tubing and reassemble
- Disconnect and drain the water from the pressure differential switch feed tubes. Reconnect the feed tubes if it is a Midwest pressure differential switch. If using ADI–P, leave the sensor tubes disconnected for the winter months
- If your filter is hydraulically operated, disconnect and drain the feed tubes to the hydraulic turbine/actuator, pressure differential switch, relay, and piston. Reconnect the feed tubing
- Disconnect all power sources to the unit. Power-off the control panel for SAF, ABF, EBS, and Omega filters. Remove the batteries or unplug the power adapter for ADI–P, Filtron, AMC controllers for the duration of the winter season
Manual / Semi-Automatic Filters
- Drain the filter housing and remove the screen element. Clean the screen with a high-pressure washer and reassemble it into the drained filter
- Open the ball valve halfway and leave as is for the duration of the winter season
3 Tips for Keeping Your Filtration System Safe
Other than preparing your filtration system, you should be preparing the rest of the irrigation system for winter, too. Here are the 3-most important tips that can help protect your entire system from the ravages of freezing weather:
- Drain the pipes – As the ambient temperature approaches freezing, water will begin to expand. If the water is in a closed environment (such as your pipes, filtration system, etc.) – the expansion will increase the pressure in the system, forcing the water to find an outlet. That outlet may end up being a valve, a pipe, a part of the filtration system, and so on, causing anything from minor to major damage to the system. To prevent this from happening, use a manual or automatic drain valve. Alternatively, you can use compressed air to clear the system (a method known as blow-out).
- Insulate your assets – one of the best protection methods against the cold is insulation. It is important that you insulate important parts of your system, such as your backflow preventers, main and secondary valves, and even above-ground pipes. Insulation can be done by using spray foam insulation on the valves and wrapping them up in a plastic bag for extra protection.
- Leave manual valves halfway open – manual valves will hold a small amount of water in them. By leaving the valve halfway open (45 degrees) the water will have a harder time freezing – this will save you time and material in the spring.
Video: Winterizing a Mini Sigma Filter
Still Not Sure?
The above directions are provided to prepare filters for extended periods of non-operation under freezing conditions. Only experienced personnel should attempt this procedure. Please refer to the filter’s manual instructions provided with your specific filter. If you have any questions or require any additional information, please contact an authorized Amiad representative.