Beginners Guide: Irrigation Filters
Installing a filter on your drip irrigation system prevents clogging of emitters and reduces wear and tear on the system. Sand and organic materials are the primary objects you want to remove. Filters require minor maintenance are fairly inexpensive and help provide reliable use of drip irrigation season after season.
Types Of Filters
Screen Filters – These are the least expensive and most common filters. They work well removing sand from water. In situations when you need to remove large amounts of organic material from water you have better choices. The organic materials tend to crush on the screen and are hard to remove.
Cleaning screen filters is easy and should be done regularly. For irrigation systems pulling municipal water, cleaning your filters once a month during the irrigation season is sufficient. You can remove the filter and clean it by hand. Flushing screen filters clean themselves and are an excellent choice for water managers wanting to reduce time spent on maintenance. Many filters have flush outlets. Opening the outlet and letting the water flush the screen works well. Some filters open a flush valve every time the system is charged. This is especially helpful for dirty water applications.
Plastic Spin Clean Filters – Unique screen filters that stay clean during operation. They effectively keep debris moving across the screen element towards the basin, where it is collected and can be drained. The 4E Plastic Spin Clean® Filter is best suited for applications where the contaminants are heavy particles like sand. Jain Spin Clean Filters are available in sizes of 3/4″, 1″, 1 1/2 and 2″. With mesh sizes of 30, 50, and 150 available.
How does a spin clean filter work?
Incoming unfiltered water from the inlet is forced though the nozzles of a stationary spin plate at the top of the filter screen element. These nozzles blast water across the inside screen surface, continuously sweeping the screen clean, spinning debris toward the basin where it is collected. Each filter model is designed to self-clean over a flow range corresponding to pressure differentials between the inlet and outlet of the filter of from 5-8 psi. As long as the flow through the filter is sufficient to produce these pressure differentials, a strong self-cleaning action will be maintained. These flow ranges are shown for each filter model in the flow range charts. These pressure differentials are critical for the filter to run long periods without maintenance. Operating the filter at less than the minimum pressure differential will reduce the cleaning action resulting in more frequent screen clogging and disassembly to remove and clean the screen. 4E Spin Clean models usually require only periodic flushing of contaminants from the drain basin. With higher loading of contaminants it may be necessary to flush more frequently or on a continuous basis with a small flow of water.
Media Filters – The media commonly used in media filters is sand. Many people recognize this from their swimming pool filters. Water is forced through crushed sand and any debris is stopped when it can’t fit between the spaces. To work effectively the media has to have sharp edges. It is very important to match the sand you are using to what you are filtering. For example if you need a 150 mesh filtering be sure to use #16 size sand.
Disk filters – A cross between a screen filter and a media filter, with many of the advantages of both. A disk filter is full of round-stacked disks (think poker chips) that allow water to pass through but are excellent at catching organic material and sand. These filters can be automatically flushed or manually cleaned.
It is important to match your filter to your unique water requirements. No matter how clean your water is every irrigation system needs to have a filter. Filters are inexpensive insurance to guard against debris entering your irrigation system. Even small particles in the water can cause drip emitters to become clogged and typically we don’t notice a clog emitter until we have damaged plant material. Let us know if you have additional questions about filters. If you enjoyed this article please consider subscribing to the blog or follow me on twitter @H2oTrends