What is self cleaning filter?
Types and applications of self-cleaning filters
1. Multi-media filter
Multi-media filter refers to the usual use of three-layer media for multi-media filtration: anthracite, sand and stone. Because of their obvious differences in density, these media are often chosen for multi-media filters.
The shell is mainly made of epoxy coated, stainless steel or fiberglass cans. It is mainly used to remove organic clastic sediments / suspended particles from water flow.
2. Hydrocyclone
The hydrocyclone is used to remove sand and other fine solids from water. The desanding machine works by centrifugal force. Centrifugal force separates sand from the water. Clean water is forced into the center of the separator and goes up through an outlet. The sand removed from the water is then collected in the collection room at the bottom of the separator. The shell is mainly made of tapered steel chamber, and there is a debris collection area at the bottom, which is mainly used to remove large granular sand.
3. Disc filter
Disc filter is a kind of water filter mainly used for wastewater treatment, which is similar to the screen filter, except that the filter cylinder is composed of many superimposed disks, and the water is trapped through the small grooves between them. Impurities are trapped inside.
The shell is mainly made of high density polyethylene and is mainly used for agricultural drip irrigation.
4. Self-cleaning Screen Filter
The internal filter element of the self-cleaning screen filter is wedge-shaped screen or stainless steel braided mesh medium. Cost-effective, efficient and space-saving, while reducing maintenance.
The shell is mainly composed of carbon steel, S304, S316 stainless steel and other materials, which is mainly used for clarification and filtration of industrial sewage.
Technical parameters need to be considered before selecting a mechanical self-cleaning filter
- Flow
It is usually expressed in gallons per minute. The minimum and maximum flow rates need to be checked to select the filter correctly.
- Pressure
It is generally expressed as P.S.I (pounds per square inch). The minimum and maximum pressure during self-cleaning need to be checked.
- Water source
Well water, ponds or reservoirs, sewage, processed seawater, canals.
- Detritus
Organic, inorganic or combined. The amount of debris is usually expressed as PPM (particles per million). The size of particles is usually expressed in microns.
- Discharge port
The size of the protected device can be expressed in inches or millimeters.
- Cleaning method
Filter flushing can be done manually or automatically.
What should be done when the filter cake is piled up?
Self Cleaning Filters’ Operation and Maintenance
1. Operation and maintenance of multi-media filters
1) Turn off the system pump and disconnect the power of the automatic controller. Open the upper inspection port of each filter tank to check the quantity and quality of media sand. The loss of sand indicates that there is too much backwashing. The existence of contaminants or mucus indicates insufficient backwashing.
2) Through the automatic controller, press the manual button for one second to start the manual backwashing cycle. Each filter tank shall be backwashed in accordance with the procedure. Pay attention to the packing time and backwashing time.
3) Check that all pipes and components are properly connected and damaged.
4) Check the pre-filter on the intake pipe: clean the internal filter if necessary.
5) Check the expected reading of the pressure gauge.
Seasonal shutdown process
SAIFILTER recommends that all storage tanks be closed when they are not in use for a long time.
Backwash all filter tanks in the system for a long time and to a certain extent, backwash each tank for at least two minutes, and the opening of the backwash throttle valve is slightly higher than normal operation.
Note: if any chemical is introduced into the irrigation system during shutdown, it should be downstream of the filtration system. If you are upstream, you should rinse through the filtration system with clean water before shutting down the filtration system at the end of the season.
Turn the system pump and power off the automatic controller, if applicable. Open each filter tank and check the sand quantity and quality. If extra or new sand is needed, be careful to add the necessary sand before starting the device before next season.
Warning: if the inspection finds that there are too many contaminants in the mucus or sand medium anywhere in the tank, it means that all medium sands need to be replaced. Remove all sand from the media tank at this time, but do not introduce new sand until the start of the next season.
Completely drain all water from the filter system. It is best to open the coupling connection on the outlet manifold of the filter system to ensure that all water is discharged from the lowest point of the filter system.
Drain all the water in the filtration system. Open the coupling on the outlet manifold of the filtration system to ensure that all water is discharged from the lowest point of the filtration system.
Clean the strainer in the pre-filter on all system intake components. In order to achieve the best life expectancy. Lubricate the inner shaft of each backwash valve.
Troubleshooting
| Analysis of the possible reasons for the poor filtering effect | Solution |
| The flow through the filter is too large, causing the media sand to “taper” and / or force the contaminants to pass through the filter outlet. | Reduce the flow rate or add additional filter tanks |
| The air in the tank may lead to the rupture of the medium sand layer. | Drain the trapped air from the system |
| wrong medium sand | Replace the appropriate medium sand. Consult your supplier. |
| The pressure difference before backwashing is too high, forcing the contaminants to pass through the filter layer. | Backwash more often at lower pressure difference. |
| Insufficient media capacity in the filter, causing pollutants to pass through the system. | Add appropriate sand medium to the tank to the specified liquid level. |
| Analysis of possible causes of continuous high pressure difference. | Solution |
| Excessive pollutant load limits the flow through the filter and prevents sufficient backwashing flow. | Empty the pitcher and remove the manhole entrance. Carefully remove excess or caked contaminants from the surface of the media sand bed. Restore the normal operation of the water tank and the backwashing system. |
| Insufficient backwashing flow. | Re-adjust the backwash or partially close the field valve. |
| The insufficient volume of the medium sand may minimize the coverage of the backwashing flow through the filter bed, thus forming a dead point for the accumulation of pollutants. | And add sand media as needed. |
| Analysis of the possible reasons for the increase of the frequency of backwashing cycle. | Solution |
| The backwashing flow rate or duration is not sufficient to flush all pollutants in the filter. | Adjust backwashing flow or duration |
| Insufficient sand | Add medium sand to achieve the right volume. |
| Increased concentration of pollutants in water supply | Adjust the backwashing frequency or reduce the differential pressure setting to achieve a more frequent backwashing cycle. |
| Analysis of the possible reasons for the failure of automatic backwashing to circulate. | Solution |
| The controller may be powered off or the circuit breaker may be tripped. | Make sure the wiring is connected correctly. Reset the circuit breaker. |
| The differential switch is set incorrectly | Turn on the power. The controller may be faulty and needs to be replaced. Make adjustments if necessary. Typical values are 6-7 psi. |
| Solenoid valve failure. | Check the connection, clean the port, and check the solenoid valve for startup sound. Replace the solenoid valve if necessary |
| Lose enough pressure to drive the valve | Check the strainer on the suction kit and hydraulic lines for blockage or rupture / leakage. Replace if necessary. |
| Analysis on the possible causes of the occurrence of sand media downstream. | Solution |
| Incorrect sand medium (that is, too fine and too small | Replace the media with a medium of the appropriate size |
| The side is damaged, damaged, or missing | Repair or replace the side of the culvert |
| Analysis on possible causes of leakage of backwash valve | Solution |
| Valve seat blockage | Remove obstacles |
| Rubber seat disc wear or damage | Replace the seat plate |
| Damage to the diaphragm (leakage from the exhaust hole located in the piston cavity) | Replace the diaphragm |
| Analysis on the possible causes of Water Hammer. | |
| There is air in the can | Drain the trapped air from the system. Exhaust vents may need to be installed on the system. |
| A long backwash line creates a vacuum | Install vacuum circuit breaker on backwash line |
2. Operation and maintenance of hydrocyclones
When the guide plate on the hydrocyclone is not less than 3 psi (the recommended range is 3-8 psi), the normal working conditions can be achieved. The head loss of less than 3 psi will reduce the separation efficiency, while the head loss of more than 8 psi may lead to the increase of erosion. The maximum recommended working pressure for hydrocyclones is 120 psi, and should not exceed 150 psi. Sedimentation tank flushing The sedimentation tank can be flushed manually or automatically by an irrigation controller or computer on a regular basis. When installing manual valves. According to the recommendation, the sedimentation tank should be drained regularly. When the sedimentation tank is full, the water in the sedimentation tank should be drained. Do not make the amount of water injected into the sedimentation tank exceed its capacity, otherwise, the sand will not be washed properly. Regular cleaning of the sedimentation tank Check the rubber sleeve for wear or damage and replace it if necessary. When separating sand, rubber inserts may need to be replaced every 2-3 years. When separating the sludge, it may be necessary to replace the rubber pad every year. Close the hydrocyclone inlet valve. Open the drain valve at the bottom of the sedimentation tank to relieve pressure and drain. Take off the lid. Remove all sediments collected from the sedimentation tank. Thoroughly flush the interior of the empty sedimentation tank. Replace the lid on the sedimentation tank so that the lid washer fits it. Install the fastening bracket and tighten the handle correctly. Warning: do not tighten or open the lid during operation or under pressure. Maintenance Video link（https://vimeo.com/173883191）
Apply a layer of grease on the thread every year.
Repair any damage to the protective coating of the tank immediately.
3. Operation and maintenance of disc filter
Open the blind flange connection of the inlet manifold and flush the main line upstream of the filter. After initial flushing, reassemble the blind flange.
Slowly turn on the system to increase pressure. Start the backblow cycle to ensure that all system components are operating properly.
After backblowing, please check that the PD pressure gauge reading is zero.
If the filter is loaded during startup:
Close the downstream (flow control) valve to increase the pressure downstream of the filter.
Start the backblowing cycle until the filter plate is clean. Slowly reopen the downstream valve.
If the pressure difference is still high, check whether the flow rate is too high. Excessive flow through the filter will lead to excessive pressure loss.
General requirements and maintenance:
Confirm that the downstream pressure of the filter is 30 psi during backwashing. Check that the PD gauge returns to 0-2 psi after recoil.
All exhaust pipes need to be freely discharged into the atmosphere without any back pressure.
In order to minimize damage to the recoil controller, always close the door and turn off the power supply when the controller is not in use for a long time.
Seasonal maintenance:
At the end of the irrigation season, start the recoil with the required pressure and turn off the water before closing. This ensures that the filter disc is kept clean during downtime.
Manually clean the filter plate if necessary. To prevent the filter from being damaged in freezing conditions, drain all water from the filter and keep the discharge valve open.
Video link（https://youtu.be/V4NtlraUXsA）
Troubleshooting
1) No water passes through the filter:
If the system has upstream and downstream valves around the filter, check to make sure they are open. Check whether the valve is open on site.
At start-up, the recoil valve requires at least 12 psi to start working. If there is air in the system, close the downstream butterfly valve to increase the pressure at the filter. Then, slowly open the butterfly valve and let the water flow into the field.
Verify that the manual buttons on all solenoid valves are in the correct position. If all manual overdrive buttons are in the wrong position, the water will not flow through the filter. Ensure that all vents are discharged into the atmosphere without back pressure.
2)No recoil operation
Check upstream and downstream pressure.
During backwashing, the pressure downstream of the filter should be at least 30 psi. Keep pressure normally open (PSNO). During backwashing, the valve should be set to at least 30 psi.
Check filter instruction
Make sure the instructions are correct. The wrong command will not supply water to the solenoid and recoil valves, and the filter will not flush. At the same time, make sure the ball valve in front of the instruction filter is open.
Check the differential pressure (PD) gauge
Make sure the PD gauge is not broken. The set value (short needle) should be set to 5 psi. The long red needle indicates the pressure difference at any time. If the pointer reading is zero, the disk is clean. When the red pointer moves toward the shorter (set value) pointer, the valve disc becomes dirty. When the two needles come into contact, the recoil controller will start the flushing cycle.
Check if the filter disc is clogged.
To check if the filter disc is clogged, turn off the water and make sure there is no pressure in the system. Open the filter cover and check the disc. If all filters are completely blocked, the filters will not be flushed. Remove the filter disc and clean it, reassemble the disc and filter cover on the spine, and then tighten the clamp. If the filter still cannot be flushed, use the recoil controller to start the recoil.
Check recoil controller
To test the recoil controller, press the black button (manual override) to start the recoil. The solenoid valve should click and send the filter into flushing mode. After 20 seconds, the solenoid valve should click again and end the recoil.
If the solenoid valve clicks. Then the solenoid valve works and the control panel does not work. If the solenoid valve does not click, the solenoid valve needs to be replaced.
Test solenoid valve: remove the wire of the solenoid valve from the terminal of the control panel and connect it directly to the power supply. For DC models. Touch the wire. For AC models. Connect the solenoid valve wire to the outlet transformer wire.
If the recoil is not activated. Check the wires to verify that all connections are secure. Press the reset button on the front panel to start the recoil function.
3)Continuous recoil:
Continuous flow of drainage manifold.
If water continues to flow through the drain manifold, one of the recoil valves is stuck in the flushing position. This may be caused by one of the following three problems:
There may be debris stuck in the discharge port of the recoil valve, making it impossible for the valve to return to the filter position. Determine which valve has been flushing. Turn the manual switch of the solenoid valve to the flushing position and return the knob to filter. Make sure the knob is in the correct position. If the valve is still flushing, turn off the water.
If the fault moves with the stuck solenoid valve, the fault occurs in the solenoid valve. Disassemble the solenoid valve to remove any debris. If the problem persists, replace the new solenoid.
The diaphragm of the backflush valve may be torn. To confirm, close the ball valve in front of the instruction filter. If the water is still flushed from the drainage manifold, the diaphragm may be torn. Turn off the water and remove all bolts from the bonnet. Remove the diaphragm and check for tears. Replace if necessary.
4)The filter completes a recoil cycle, stops and recoils again:
If the filter recoils continuously through a cycle, stop for 1 minute, and then recoil again, check to see if the word “alarm” on the controller flashes. If so, the filter may be clogged.
5)The filter can be blocked for the following reasons:
During backwashing, the pressure on the downstream side of the filter is less than 30 psi. The water quality changes and becomes too dirty to keep the filter running. Check to see if there is a large number of algae or a high amount of silt. Increase the flow by opening an additional valve, so the filter cannot keep up with the increased flow.
The diameter of the drain is too long or too small, or it is so vertical that it rises into the tank. All of these will produce back pressure on the filter during the flushing process and have a negative impact on the flushing quality.
The drain pipe should be at least 4 inches in diameter, no more than 50 feet long and can flow freely into the drain. If the drain needs to be more than 50 feet, use a 6-inch pipe. There should be no check valve or gate valve on the drain.
4. Self-cleaning screen filter control system
Automatic operation
Hydraulic cleaning controller
High and low pressure signals and hydraulic movement of the diaphragm are used to start and control the backwashing cycle.
Electronic cleaning controller.
The DP switch monitors the voltage drop. It signals to the PLC controller, which operates the solenoid valve electrically to start and control backwashing.、
Manual operation.
Hydraulic cleaning controller
Hydraulic cleaning controller.
A small three-way valve controls the flow of water to the controller. At the “A” position (automatic), the filter flushes automatically. Move to the “C” position (clean) for a few seconds, then return to “A” to manually remove the filter. Keeping the valve in a “clean” position will result in continuous flushing. Do not use the third location “O” (open).
Electronic cleaning controller
A button marked “manual flush” is provided on the controller panel. You will hear the click of the solenoid valve and then start the backwash cycle. The amber light indicates that a backblow is in progress. The red light on the panel indicates that the recoil is too frequent.
Pressure diagnosis.
A pressure gauge with a three-way valve is installed on the filter body (two pressure gauges are required), which enables the operator to observe the pressure in the inlet, outlet and drain chamber. During cleaning, the pressure difference between the inlet and outlet should be between a minimum of 15psidy and a maximum of 35psid.
Video link（https://youtu.be/cn7jhKPjKyM）
Self-cleaning filter maintenance
Most self-cleaning filters only need to be checked half a year. Open the lid, determine whether the internal brush mechanism rotates properly, and confirm that the screen is intact.
Remove the internal screen and clean it with a water cannon.
There should be no gap between the cleaning brush and the screen for a full cleaning.
The O-ring at the end of the filter should be lubricated with pipe industrial grease (such as Dow Corning DC33 or other silicone).
Manual backwashing should be performed regularly to verify the correct flushing cycle, cycle time, and pressure.
Troubleshooting
Filter backflushing is too frequent (a red “frequent flush” alert appears on the PLC panel). It is usually caused by excessive flow, insufficient screen area or too much dirt. A filter needs to be added in parallel.
Insufficient cleaning of the screen may also be the reason. This is almost always caused by insufficient inlet pressure. Check to see if it is at least 30psi. If lower, add a booster pump.
Although the DP is high, the filter will not backwash. In a filter with a hydraulic flushing controller, the suspected emitter is clogged. The emitter cannot be cleaned and must be replaced.
In the filter with electronic flushing controller, check that the operation of the solenoid valve and action switch is normal. Also check the hydraulic line to the DP switch.
The strainer that is seriously clogged due to too much dirt or no backwashing operation can be cleaned manually.
Remove the strainer and soak it for 24 hours. Use 900psi’s high-pressure cleaner for spray cleaning.
How long do self cleaning filters last?
The life of a typical filter is expected to exceed 20 years. This actually depends on the chemical properties of the water and the frequency of flushing.
Troubleshooting
| Analysis of the possible reasons for the poor filtering effect | Solution |
| The flow through the filter is too large, causing the media sand to "taper" and / or force the contaminants to pass through the filter outlet. | Reduce the flow rate or add additional filter tanks |
| The air in the tank may lead to the rupture of the medium sand layer. | Drain the trapped air from the system |
| wrong medium sand | Replace the appropriate medium sand. Consult your supplier. |
| The pressure difference before backwashing is too high, forcing the contaminants to pass through the filter layer. | Backwash more often at lower pressure difference. |
| Insufficient media capacity in the filter, causing pollutants to pass through the system. | Add appropriate sand medium to the tank to the specified liquid level. |
| Analysis of possible causes of continuous high pressure difference. | Solution |
| Excessive pollutant load limits the flow through the filter and prevents sufficient backwashing flow. | Empty the pitcher and remove the manhole entrance. Carefully remove excess or caked contaminants from the surface of the media sand bed. Restore the normal operation of the water tank and the backwashing system. |
| Insufficient backwashing flow. | Re-adjust the backwash or partially close the field valve. |
| The insufficient volume of the medium sand may minimize the coverage of the backwashing flow through the filter bed, thus forming a dead point for the accumulation of pollutants. | And add sand media as needed. |
| Analysis of the possible reasons for the increase of the frequency of backwashing cycle. | Solution |
| The backwashing flow rate or duration is not sufficient to flush all pollutants in the filter. | Adjust backwashing flow or duration |
| Insufficient sand | Add medium sand to achieve the right volume. |
| Increased concentration of pollutants in water supply | Adjust the backwashing frequency or reduce the differential pressure setting to achieve a more frequent backwashing cycle. |
| Analysis of the possible reasons for the failure of automatic backwashing to circulate. | Solution |
| The controller may be powered off or the circuit breaker may be tripped. | Make sure the wiring is connected correctly. Reset the circuit breaker. |
| The differential switch is set incorrectly | Turn on the power. The controller may be faulty and needs to be replaced. Make adjustments if necessary. Typical values are 6-7 psi. |
| Solenoid valve failure. | Check the connection, clean the port, and check the solenoid valve for startup sound. Replace the solenoid valve if necessary |
| Lose enough pressure to drive the valve | Check the strainer on the suction kit and hydraulic lines for blockage or rupture / leakage. Replace if necessary. |
| Analysis on the possible causes of the occurrence of sand media downstream. | Solution |
| Incorrect sand medium (that is, too fine and too small | Replace the media with a medium of the appropriate size |
| The side is damaged, damaged, or missing | Repair or replace the side of the culvert |
| Analysis on possible causes of leakage of backwash valve | Solution |
| Valve seat blockage | Remove obstacles |
| Rubber seat disc wear or damage | Replace the seat plate |
| Damage to the diaphragm (leakage from the exhaust hole located in the piston cavity) | Replace the diaphragm |
| Analysis on the possible causes of Water Hammer. | |
| There is air in the can | Drain the trapped air from the system. Exhaust vents may need to be installed on the system. |
| A long backwash line creates a vacuum | Install vacuum circuit breaker on backwash line |
2. Operation and maintenance of hydrocyclones
According to the principle of centrifugation, the particles rotate against the inner wall of the hydrocyclone and are attracted to the bottom of the sedimentation tank. The speed at which the water flows through the hydrocyclone determines the efficiency of the separation of particles from the water.
When the guide plate on the hydrocyclone is not less than 3 psi (the recommended range is 3-8 psi), the normal working conditions can be achieved. The head loss of less than 3 psi will reduce the separation efficiency, while the head loss of more than 8 psi may lead to the increase of erosion.
The maximum recommended working pressure for hydrocyclones is 120 psi, and should not exceed 150 psi.
Sedimentation tank flushing
The sedimentation tank can be flushed manually or automatically by irrigation controller or computer on a regular basis. When installing manual valves. According to the recommendation, the sedimentation tank should be drained regularly. When the sedimentation tank is full, the water in the sedimentation tank should be drained. Do not make the amount of water injected into the sedimentation tank exceed its capacity, otherwise the sand will not be washed properly.
Regular cleaning of sedimentation tank
Check the rubber sleeve for wear or damage and replace it if necessary. When separating sand, rubber inserts may need to be replaced every 2-3 years. When separating the sludge, it may be necessary to replace the rubber pad every year.
Close the hydrocyclone inlet valve. Open the drain valve at the bottom of the sedimentation tank to relieve pressure and drain.
Take off the lid. Remove all sediments collected from the sedimentation tank.
Thoroughly flush the interior of the empty sedimentation tank. Replace the lid on the sedimentation tank so that the lid washer fits it.
Install the fastening bracket and tighten the handle correctly.
Warning: do not tighten or open the lid during operation or under pressure.
Maintenance
Apply a layer of grease on the thread every year.
Repair any damage to the protective coating of the tank immediately.
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3. Operation and maintenance of disc filter
Initiated action:
Open the blind flange connection of the inlet manifold and flush the main line upstream of the filter. After initial flushing, reassemble the blind flange.
Slowly turn on the system to increase pressure. Start the backblow cycle to ensure that all system components are operating properly.
After backblowing, please check that the PD pressure gauge reading is zero.
If the filter is loaded during startup:
Close the downstream (flow control) valve to increase the pressure downstream of the filter.
Start the backblowing cycle until the filter plate is clean. Slowly reopen the downstream valve.
If the pressure difference is still high, check whether the flow rate is too high. Excessive flow through the filter will lead to excessive pressure loss.
General requirements and maintenance:
Confirm that the downstream pressure of the filter is 30 psi during backwashing. Check that the PD gauge returns to 0-2 psi after recoil.
All exhaust pipes need to be freely discharged into the atmosphere without any back pressure.
In order to minimize damage to the recoil controller, always close the door and turn off the power supply when the controller is not in use for a long time.
Seasonal maintenance:
At the end of the irrigation season, start the recoil with the required pressure and turn off the water before closing. This ensures that the filter disc is kept clean during downtime.
Manually clean the filter plate if necessary. To prevent the filter from being damaged in freezing conditions, drain all water from the filter and keep the discharge valve open.
Video link（https://youtu.be/V4NtlraUXsA）
Troubleshooting
- No water passes through the filter:
If the system has upstream and downstream valves around the filter, check to make sure they are open. Check whether the valve is open on-site.
At start-up, the recoil valve requires at least 12 psi to start working. If there is air in the system, close the downstream butterfly valve to increase the pressure at the filter. Then, slowly open the butterfly valve and let the water flow into the field.
Verify that the manual buttons on all solenoid valves are in the correct position. If all manual overdrive buttons are in the wrong position, the water will not flow through the filter. Ensure that all vents are discharged into the atmosphere without back pressure.
- No recoil operation
Check upstream and downstream pressure.
During backwashing, the pressure downstream of the filter should be at least 30 psi. Keep pressure normally open (PSNO). During backwashing, the valve should be set to at least 30 psi.
Check filter instruction
Make sure the instructions are correct. The wrong command will not supply water to the solenoid and recoil valves, and the filter will not flush. At the same time, make sure the ball valve in front of the instruction filter is open.
Check the differential pressure (PD) gauge
Make sure the PD gauge is not broken. The set value (short needle) should be set to 5 psi. The long red needle indicates the pressure difference at any time. If the pointer reading is zero, the disk is clean. When the red pointer moves toward the shorter (set value) pointer, the valve disc becomes dirty. When the two needles come into contact, the recoil controller will start the flushing cycle.
Check if the filter disc is clogged.
To check if the filter disc is clogged, turn off the water and make sure there is no pressure in the system. Open the filter cover and check the disc. If all filters are completely blocked, the filters will not be flushed. Remove the filter disc and clean it, reassemble the disc and filter cover on the spine, and then tighten the clamp. If the filter still cannot be flushed, use the recoil controller to start the recoil.
Check recoil controller
To test the recoil controller, press the black button (manual override) to start the recoil. The solenoid valve should click and send the filter into flushing mode. After 20 seconds, the solenoid valve should click again and end the recoil.
If the solenoid valve clicks. Then the solenoid valve works and the control panel does not work. If the solenoid valve does not click, the solenoid valve needs to be replaced.
Test solenoid valve: remove the wire of the solenoid valve from the terminal of the control panel and connect it directly to the power supply. For DC models. Touch the wire. For AC models. Connect the solenoid valve wire to the outlet transformer wire.
If the recoil is not activated. Check the wires to verify that all connections are secure. Press the reset button on the front panel to start the recoil function.
- Continuous recoil:
Continuous flow of drainage manifold.
If water continues to flow through the drain manifold, one of the recoil valves is stuck in the flushing position. This may be caused by one of the following three problems:
There may be debris stuck in the discharge port of the recoil valve, making it impossible for the valve to return to the filter position. Determine which valve has been flushing. Turn the manual switch of the solenoid valve to the flushing position and return the knob to filter. Make sure the knob is in the correct position. If the valve is still flushing, turn off the water.
If the fault moves with the stuck solenoid valve, the fault occurs in the solenoid valve. Disassemble the solenoid valve to remove any debris. If the problem persists, replace the new solenoid.
The diaphragm of the backflush valve may be torn. To confirm, close the ball valve in front of the instruction filter. If the water is still flushed from the drainage manifold, the diaphragm may be torn. Turn off the water and remove all bolts from the bonnet.
Remove the diaphragm and check for tears. Replace if necessary.
- The filter completes a recoil cycle, stops, and recoils again:
If the filter recoils continuously through a cycle, stop for 1 minute, and then recoil again, check to see if the word “alarm” on the controller flashes. If so, the filter may be clogged.
- The filter can be blocked for the following reasons:
During backwashing, the pressure on the downstream side of the filter is less than 30 psi. The water quality changes and becomes too dirty to keep the filter running. Check to see if there is a large number of algae or a high amount of silt. Increase the flow by opening an additional valve, so the filter cannot keep up with the increased flow.
The diameter of the drain is too long or too small, or it is so vertical that it rises into the tank. All of these will produce back pressure on the filter during the flushing process and have a negative impact on the flushing quality.
The drain pipe should be at least 4 inches in diameter, no more than 50 feet long and can flow freely into the drain. If the drain needs to be more than 50 feet, use a 6-inch pipe. There should be no check valve or gate valve on the drain.
4. self-cleaning screen filter control system
Automatic operation
Hydraulic cleaning controller
High and low pressure signals and hydraulic movement of the diaphragm are used to start and control the backwashing cycle.
Electronic cleaning controller.
The DP switch monitors the voltage drop. It signals to the PLC controller, which operates the solenoid valve electrically to start and control backwashing.、
Manual operation.
Hydraulic cleaning controller
Hydraulic cleaning controller.
A small three-way valve controls the flow of water to the controller. At the “A” position (automatic), the filter flushes automatically. Move to the “C” position (clean) for a few seconds, then return to “A” to manually remove the filter. Keeping the valve in a “clean” position will result in continuous flushing. Do not use the third location “O” (open).
Electronic cleaning controller
A button marked “manual flush” is provided on the controller panel. You will hear the click of the solenoid valve and then start the backwash cycle. The amber light indicates that a backblow is in progress. The red light on the panel indicates that the recoil is too frequent.
Pressure diagnosis.
A pressure gauge with a three-way valve is installed on the filter body (two pressure gauges are required), which enables the operator to observe the pressure in the inlet, outlet and drain chamber. During cleaning, the pressure difference between the inlet and outlet should be between a minimum of 15psidy and a maximum of 35psid.
Video link（https://youtu.be/cn7jhKPjKyM）
Self-cleaning filter maintenance
Most self-cleaning filters only need to be checked half a year. Open the lid, determine whether the internal brush mechanism rotates properly, and confirm that the screen is intact.
Remove the internal screen and clean it with a water cannon.
There should be no gap between the cleaning brush and the screen for full cleaning.
The O-ring at the end of the filter should be lubricated with pipe industrial grease (such as Dow Corning DC33 or other silicone).
Manual backwashing should be performed regularly to verify the correct flushing cycle, cycle time and pressure.
Troubleshooting
Filter backflushing is too frequent (a red “frequent flush” alert appears on the PLC panel). It is usually caused by excessive flow, insufficient screen area or too much dirt. A filter needs to be added in parallel.
Insufficient cleaning of the screen may also be the reason. This is almost always caused by insufficient inlet pressure. Check to see if it is at least 30psi. If lower, add a booster pump.
Although the DP is high, the filter will not backwash. In a filter with a hydraulic flushing controller, the suspected emitter is clogged. The emitter cannot be cleaned and must be replaced.
In the filter with electronic flushing controller, check that the operation of the solenoid valve and action switch is normal. Also check the hydraulic line to the DP switch.
The strainer that is seriously clogged due to too much dirt or no backwashing operation can be cleaned manually.
Remove the strainer and soak it for 24 hours. Use 900psi’s high-pressure cleaner for spray cleaning.
How long do lastself-cleaning filters last?
The life of a typical filter is expected to exceed 20 years. This actually depends on the chemical properties of the water and the frequency of flushing.