Generally, before diagnosing the problem of irrigation solenoid valves (sprinkler solenoid valves), some work needs to be done: such as determining whether the water source is turned on, whether the controller is connected to the power supply and the program setting is correct, whether the flow control handle on the solenoid valve is closed, and then try operating the valve manually. If the solenoid valve can work normally when operated manually, the problem may be in the controller, solenoid or cable.
1. Determine whether the controller has normal output?
Generally, the output of an irrigation AC controller is about 24V, and that of a pulse controller is about 12V. Check the solenoid valve controller first, so that customers do not think and conclude that there is a problem with the solenoid valve when the valve cannot be opened.
Use a multimeter to measure the voltage of the output port of the solenoid valve controller. If there is a problem with the output, troubleshoot it. If not, proceed to the next step.
2. Check whether the connecting cable between the solenoid valve and the controller is connected?
If a wireless control system is used, ignore this step. Measure the control signal cable by using the resistance range of the multimeter. Infinity represents a circuit break, and the normal resistance value is more than ten to tens of ohms, which depends on the length and material of the cable.
3. The last step is to troubleshoot the solenoid valve failure. In addition to the damage to the valve body, which is easy to judge, other two common problems are: the solenoid valve cannot be opened and the solenoid valve cannot be closed.
1. Common Faults, Causes and Troubleshooting of Irrigation Solenoid Valves
1.1 Solenoid Valve Unable to Be Closed
There may be two reasons for this.
First: Physical obstacles, such as some gravel, dead leaves and branches, prevent the diaphragm from being completely sealed. After removing these obstacles, it is necessary to check whether the diaphragm and related accessories are damaged.
Second: Pressure acting on the upper diaphragm is too small. This may be caused by the following:
1. The inlet filter of the upper diaphragm chamber is blocked, which will prevent water from entering the upper diaphragm chamber, so there is not enough water pressure generated to close the valve.
2. The seal between the upper and lower valve bodies of the solenoid valve is not tight or the pipe joint is not connected well, and water can easily seep out of it, which is not conducive to generating enough pressure to close the valve. At this time, the valve body fixing screws need to be tightened.
3. The solenoid valve is in the manual water bleed state. There are two manual operation modes for solenoid valves (internal water bleed and external water bleed). The external water bleed is generally easy to identify, while internal water bleed is not easy to detect for general customers. That is, the solenoid is not tightened, which is often neglected in the process of switching from manual to automatic operation.
4. There are small holes on the diaphragm. So not enough pressure can be generated in the upper diaphragm chamber to close the valve. Check carefully and replace the diaphragm if necessary.
5. The installation direction of the solenoid valve is incorrect. The arrow direction on the solenoid valve is the direction of water flow, and pay attention when installing.
1.2 Solenoid Valve Unable to Be Opened
There are mainly two reasons. One may be that the flow control handle is rotated too tightly (for valves with flow control handles) and the valve is closed.
The other is that the pressure in the upper diaphragm chamber is not released. The following may be the reasons:
1. The solenoid is damaged. Use a multimeter to measure the resistance value of the solenoid at this time, so that you can determine whether the solenoid is bad. For specific reference, refer to the resistance value provided by each manufacturer.
2. Damaged diaphragm. No enough force can be generated to open the valve.
3. The inlet and outlet holes under the solenoid (with a filter inside) or the channel connected to the upper diaphragm chamber are blocked. This prevents the water in the upper diaphragm chamber from escaping and the pressure cannot be reduced. Clear the blockage and clean it.
4. The voltage applied to the solenoid is not enough (about 12V needed for pulse type, about 24V for AC type). This may be a wiring problem (too small wire size, too much pressure drop) or a connection problem between the wires (there is a leakage).
2. FAQs about Irrigation Solenoid Valves
2.1 Why Does My Valve Leak when It Is Closed?
There may be debris in the valve that causes the valve to remain open. To solve this problem, you need to disassemble the valve, rinse all parts with clean water, and then reassemble the valve.
2.2 Why Does My Valve Continue to Run Even When It Is Turned Off?
Your valve may have been opened manually. You need to find your valve box and turn the solenoid on the valve clockwise until it is snug. The solenoid is located on the top of the valve and is a cylinder with two wires.
There may be debris in the valve that is holding it open. To fix this, you need to disassemble the valve, rinse all parts with clean water, and then reassemble the valve.
2.3 How Do I Manually Open a Zone Control Valve without Using a Controller?
Simply turn the solenoid (black cylinder) counterclockwise on the valve 1/4 to 1/2 turn. To close the valve, turn the solenoid clockwise until it is snug against the valve.
2.4 Why Sprinkler Valve Solenoid Buzzing?
A buzzing sound from a sprinkler valve solenoid typically indicates an electrical issue. This could be caused by several factors:
Low Voltage: If the solenoid is not receiving enough voltage to operate properly, it may buzz as it attempts to activate the valve.
Mechanical Issues: Mechanical obstructions or damage to the valve assembly can cause the solenoid to buzz as it struggles to operate the valve.
Dirty or Faulty Contacts: Accumulation of dirt or debris on the electrical contacts can interfere with the solenoid's operation, leading to buzzing.
Faulty Solenoid: A solenoid nearing the end of its lifespan or one that has become damaged may buzz as it fails to operate correctly.
Inspecting the solenoid and its connections can help identify the underlying cause of the buzzing sound, allowing for appropriate troubleshooting and repairs.
3. Conclusion
In general, irrigation solenoid valves are an important part of farmland irrigation systems, but they often fail during use. When encountering a failure, you can check and solve the problem according to the above listed failures and troubleshooting methods to ensure the normal operation of the farmland irrigation system. At the same time, check and maintain the solenoid valve regularly to extend the service life of the equipment.
