The minor problems in the functioning of the control valve can become the reason for a big problem and can also harm the whole system. They are referred to as the muscles of the processing system.
The working and performance of the electronic pneumatic flow control valves goes down with the passage of time. Sometimes you can easily spot the issues that are affecting the performance of the electronic air flow control valve but sometimes it becomes difficult to find out the fault. In this kind of situation, the problem can be found with the experienced eye.
Common Proportional Flow Control Valve Problems:
If you are using a system in which you have to use the controlled amount of a fluid to make the process happen. It means, you are relying on the electronic flow valves to keep your system safe and running efficiently. There are some problems that you can face with the passage of time.
Here we have listed 5 common problems of electronic pneumatic flow control valves:
Deadband:
This is a range that you provide as an input but in the result you don’t get an output. Basically, this is a range of controller signals that you use but it fails to trigger any activity of the valve. Most of the time it happens when the valve has to change the direction of the flow. As a compensation the controller should send the additional output that can make the valve to overshoot its target position and in return becomes the cause of the process to overshoot the setpoint.
Stiction:
The Word stiction is the combination of stick and friction. It causes an electronic pneumatic flow control valve to stick in a particular position. In this situation to move the valve you have to provide more force. Same like as the deadband, it goes towards the valve shooting its position and processes overshooting the set point. Resultantly, the proportional flow valve gets stuck in the new position.
Valve Erosion:
The most common problem is erosion that happens in the places of the slurry service (where the fluid is a liquid containing a significant quantity of the hard particles). Erosion damages the valve very badly and affects its performance. It can cause the electronic pneumatic flow control valve to leak and you will not have the expected outcome from the system.
Cavitation:
It can happen in any portion of the digital flow control valve and interrupts the flow of the fluid. This happens because of the vapor bubbles and happens at the time when the liquid pressure drops below the vapor pressure and as a result of the bubble collapsing creates cavitation. This can be stopped by using a tortuous flow path and expanding the flow area. You can also use the harder trim material to stop the cavitation.
Valve Chatter:
Valve chatter is a noise that comes from the electronic pneumatic flow control valve caused by the plug or the vibrations of the spindle. If you will not check the valve and let the noise come then it can damage the components of your valve. Resultantly, the performance of the valve will be reduced. It can be very harmful for your system. There are several reasons for valve chattering such as the inappropriate valve size and orientation. The return spring pressure and the conflict forces can force the valve plug to bounce inside the body and this bouncing generates the chattering sound. To resolve this issue you should reinstall the valve.
Nonlinearity:
Flow control valves are linear which means that the fluid flow enhances linearly with valve travel. Any of the above listed problems can cause nonlinearity. In this state the relationship between the flow and valve travel does not remain stable. Basically, nonlinearity affects the tuning of the controller.
Reverse Flow:
The most common problem is the reverse flow of the fluid. It occurs when the pump is discharged and causes it to spin in the opposite direction. Reverse flow is caused by the loss of pressure. Resultantly you see vibrations in the system and this reverse flow can damage the whole system. Installation of the appropriate electronic pneumatic flow control valve can reduce the chances of the reverse flow. Several factors should be considered while selecting the right valve for industrial and commercial use. So you must choose the control valve wisely by seeing the operational environment, required flow capacity, and the nature of the fluid etc.
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Final Words:
After seeing all of these common problems that occur with the electronic pneumatic flow control valves, you may be thinking of leaving them alone but this is not a good idea. You should always be familiar with the places where your valves are installed so that you can easily access them to perform the regular checkups and in the case of an emergency.
