Installation and Maintenance of Filters for Irrigation Systems

When talking about installing and maintaining filters for irrigation systems, proper installation and maintenance is crucial to the optimal performance of any irrigation filtration system. It is essential to carefully follow the manufacturer’s installation instructions, and to ensure that all components are assembled correctly and safely. For maintenance, it is important to perform regular checks and cleanings, the frequency and procedures of which may vary depending on the type of filter. Manual filters, for example, require more frequent cleaning than automatic or semi-automatic filters.

Read more about The importance of installing filters in drip irrigation networks

Maintaining Filter Efficiency in Irrigation Systems

When talking about filter efficiency, the focus has always been on the size of the filtration area, or effective filtration area. This area is defined as the total area of ​​the filter media exposed to the water flow and involved in the filtration process. To understand that filter efficiency is about more than just the size of the filtration area, let’s talk about how the efficiency of a disc filter is defined.

Traditionally, the effective filtration area is discussed in a two-dimensional context. However, when it comes to disc filtration, we must switch to a three-dimensional way of thinking.

Remember that disc filtration, like intermediate filtration, is multi-layered and provides deep filtration. This means that there are second, third, and successive chances to capture a particle in subsequent layers.

Disc filters consist of a cylinder of compressed discs. Each disc has grooves running in alternate directions that intersect when two discs are stacked on top of each other, forming a series of grids. These grooves form passages of varying dimensions through which water passes from the outside to the inside of the discs. Water is filtered as it enters the cylinder of compressed discs from the outside to the inside. The number of layers depends on the specific micron rating of the discs.

What is Dirt Holding Capacity (DHC) and How to Calculate It

Given this technical explanation of how a disc filter works, it is clear why we can think of disc filtration as three-dimensional. However, how do we measure a three-dimensional filter element? The answer is Dirt Holding Capacity (DHC).

The dirt holding capacity of a filter represents the number of particles (mg) retained on the filter media during one filtration cycle. This concept can be expressed by the following mathematical equation: Total suspended solids from backwash (mg/L) × backwash volume (L) = DHC (mg).

The DHC of a filter varies based on the type of filtration technology used (surface or depth), the quality of the water source (particle type), the operating conditions (filtration speed – Q/A, dP) and the structure of the filter element (porosity, depth, surface properties, construction materials).

The DHC will determine the backwash frequency and efficiency of the filter, which determines the filtration efficiency. A higher DHC means fewer backwash cycles as the filter can hold more dirt particles per square centimeter. In addition, fewer backwash cycles save water and energy.

The importance of a low and stable pressure loss rate

If the backwash cycle of a filter is ineffective, it will not only require more frequent backwashes; dirt will also accumulate on the filter over time. This will eventually limit the filter’s ability to function, requiring manual cleaning and interrupting irrigation. If the filter does not return to its initial pressure loss rate after a cleaning cycle, the filter’s backflow efficiency is low. This will of course reduce the pressure loss rate and increase the backflow frequency. If this inefficient backflow cycle continues, you will have to manually clean the discs more frequently.

The graph below illustrates the importance of a low and stable pressure loss rate. The filter shown in blue has a lower pressure loss rate than the filter shown in red.

A filter should not be judged by its effective filtration area alone. In the field, the filters compared above are disc filters with similar filtration areas. However, there is a significant difference in how they respond in terms of backflow frequency and pressure loss maintenance.

Maintaining Efficiency

No matter how you calculate efficiency, it cannot be maintained without proper and regular filter maintenance. Without it, you are likely to encounter problems, and the filter will fail to protect your irrigation system throughout the year.

A filter maintenance schedule can be divided into three sections:

• Weekly Maintenance
• Maintenance at the end of the irrigation season.
• Maintenance at the beginning of the irrigation season.

Screen Filter Maintenance

It is important to perform weekly visual inspections of automatic, semi-automatic and manual screen filters. The main purpose of these checks is to check for leaks, which should be repaired as soon as possible.

If you are working with an automatic screen filter and do not find any leaks, activate a manual cleaning cycle to ensure that the filter has been cleaned successfully. The next step is to check the pressure differential. If this value is abnormally high, perform two more manual cleaning cycles. If the value remains high after three manual cleaning cycles, the filter should be opened, the defective parts checked and the screen cleaned manually if necessary.

Make sure to follow the manufacturer’s step-by-step guide and all safety instructions when opening the filter and removing the screen. For cleaning when removing the screen, use pressurized water to remove any remaining dirt. Reinstall the cleaned screen according to the supplier’s instructions and follow all safety instructions.

In a semi-automatic screen filter, the cleaning process should be started before the pressure differential reaches 0.5 bar. Some semi-automatic screen filters have an automatic clog indicator that will notify you when the pressure differential limit has been reached.

Starting the cleaning process

To begin the cleaning process, open the drain valve and turn the handle all the way out and then back in. The filter will be cleaned the interior of the screen while rotating the handle and suction is generated in the nozzles. If you are working with poor water quality or low pressure. It is recommended to perform the cleaning process with the drain valve closed. Close the drain valve after the process is complete.

If the pressure difference remains abnormally high after three completed cleanings, the filter should be opened, the defective parts should be checked and the screen cleaned manually if necessary.

In a manual screen filter, a high pressure difference will always require the filter to be opened for manual cleaning. Start by shutting off the water supply to the filter and opening the drain valve to relieve the pressure completely. Open the filter body clamp and remove the filter cover. Carefully pull out the screen element and clean it with pressurized water. If necessary, use a soft nylon brush for more efficient cleaning. Never use any abrasive tools and make sure the O-rings of the body and screen are lubricated before reassembly.

Disc Filter Maintenance

The filter should undergo a general inspection on a regular basis. It should also be checked before any scheduled maintenance procedures are performed.

Check the pressure difference between the filter inlet and outlet. Then start the cleaning cycle and recheck the pressure difference one minute after the cleaning cycle is complete. If the pressure difference is still abnormally high, you will need to open the filter and remove the discs for manual cleaning. Before removing the filter cover, turn off the water supply to the filter and open the drain valve to relieve the pressure completely.

Visually inspect the discs after removing them. If there is visible deposits, clean the discs according to the supplier’s recommendations. Additionally, visually inspect the spine and ensure that the cone membrane is not damaged. If any parts of the filter are damaged, replace them immediately.

When reassembling the spine and discs, ensure that the disc count is correct. As indicated by the line on the spine, and lubricate the O-rings. Also open the command filter and clean its discs.

Media Filter Maintenance

As with disc and screen filters, it is important to inspect the media filter regularly. This type of filter is generally made of crushed basalt or graded silica sand. For successful filtration, the media must be angled with sharp edges to provide the best environment for trapping debris. The media should be replaced once the edges become rounded due to wear, so inspect it regularly.

While checking the media filter, check the pressure difference between the inlet and outlet of the system. Check the number of cleanings accumulated since the last inspection to see if the water quality is deteriorating. Start a manual cleaning process and check the proper operation and sequence. After the manual cleaning process is complete, make sure that the sand level in each tank matches the media level indicator. In addition, make sure to clean the inspection filter.

Choose the best and take care of it

Various factors determine the success of an irrigation system, and filter selection and setup is one of them. To ensure that the filtration system continues to operate effectively and for a long time. Two factors should never be neglected: using quality products and system maintenance. When it comes to product quality. The message is clear: you cannot afford to risk the financial viability of your project by not investing in the best possible irrigation equipment.

When it comes to maintenance, make sure to take the right actions at the right time to ensure that the filters are maintained and perform at their full potential.

Success Stories: Improving Performance with the Right Water Filtration System

Well Water Filtration

In the Chapanay area of ​​Mendoza, Argentina, an agricultural producer implemented an innovative approach that combined pistachio and garlic crops. The main challenge was the high concentration of sand in the well water, which threatened the efficiency and longevity of the irrigation systems. The solution came with the installation of a suitable water filtration system with 130 micron filters. Which are perfectly adapted to low-revving pumps and work efficiently with an additional booster. This advanced system has significantly improved the quality of the irrigation water. This has extended the life of the irrigation system, ensured regular irrigation and reduced operating and maintenance costs.

Water Filtration in the Orange River, South Africa

A leading raisin producer in South Africa was facing significant challenges due to the variability of water quality in the Orange River, especially during the rainy season. The challenge focused on the effective filtration of water laden with solids and organic matter. The solution was to implement two suitable water filtration systems, capable of handling a flow rate of 360 m3/h. These powerful and efficient systems allow for effective filtration at low pressure. Improve energy consumption and facilitate the reuse of backwash water. Significantly improving the sustainability and efficiency of irrigation in raisin production.

Increasing Irrigation Efficiency with the Right Filter

In short, choosing the right irrigation filter is a key step in increasing efficiency and saving water in any agricultural system. It is important to choose a filter based on the specific needs of the irrigation system and the type of water available. To make a decision based on a comprehensive understanding of the options available and their benefits. By choosing the right filter and maintaining it properly, significant improvements in irrigation efficiency can be achieved, contributing to the sustainability and productivity of agricultural practices.