how does a solenoid valve function?
July 3rd, 2009 | 
Author: I want to know that if you input different voltage or current levels, will there be a change in the flow of water. Does it open according to the level of voltage or current in the coil?
The most simple Solenoid Valve is like a plunger. The plunger holds the water from flowing into the rest of the piping. The plunger is also attached to metal core cylinder which is external to the piping. The core is "floating" inside a coil of wire. When electric current is applied to the coil, it induces a magnetic field inside and around the coil which causes the core to be pulled into it. The moving core, then, of course, releases the plunger and water flows. There usually is a spring on the other side of the core that, when the current is turned off, pushes the core and the plunger back to a closed position.
To control the amount of water is more difficult, because as mentioned above, it very much depends on how the plunger in the valve is designed. Yes, if designed in a certain way, increasing the current can strengthen the magnetic field and pull the core further into the coil.
Posted in Solenoid Valve
It is due to current, but the exact details on how much current change effects how much flow of water is specific to the actual valve.
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The most simple solenoid valve is like a plunger. The plunger holds the water from flowing into the rest of the piping. The plunger is also attached to metal core cylinder which is external to the piping. The core is "floating" inside a coil of wire. When electric current is applied to the coil, it induces a magnetic field inside and around the coil which causes the core to be pulled into it. The moving core, then, of course, releases the plunger and water flows. There usually is a spring on the other side of the core that, when the current is turned off, pushes the core and the plunger back to a closed position.
To control the amount of water is more difficult, because as mentioned above, it very much depends on how the plunger in the valve is designed. Yes, if designed in a certain way, increasing the current can strengthen the magnetic field and pull the core further into the coil.
References :
Yes, increasing or decreasing the current will change the position of the valve. most throttleing solenoids in mechanical systems are used as a kind of intermediate throttling valve however, meaning you throttle the solenoid to throttle the hydraulic/pneumatic pressure on a valve actuator for the actual system valve.They do this to have finer control over a system and ease of maintenance
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The term "solenoid valve" generally refers to a valve that is opened or closed by energizing a solenoid. In the usual configuration, if the valve is opened by energizing a solenoid, it is closed by the action of a spring when the solenoid is de-energized. The action of the solenoid does not regulate the flow of water except to turn the water on and off.
A valve that regulates flow is usually called a "control valve" or a "throttling valve." The control current does not control the valve directly but servers as a command to electronic circuitry that regulates the valve position. The actuating device is usually a small motor.
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The solenoid consists of a wire coil within which is a movable iron core
The core is attached to a valve in the water line.
When no power is being applied, a spring above the core keeps the valve closed to block the flow of water.
When the solenoid coil is energised, (current flowing through the coil), a magnetic field is produced that pulls the iron core up into the coil.
This opens the valve and the water will flow to whereever it is piped..(like into a washing machine for example).
In the washing machine, a level switch is installed that, when the water level reaches the setting of the switch, it cuts the power supply to the solenoid and the valve closes stopping the water flow. The washer then goes on to the next part of its cycle. When the washer comes to the drain part of the cycle, another solenoid is opened and the pump starts and empties the washer. At a setting in the washer cycle, the solenoid is switched closed again and the pump shuts down too.
Some solenoids are controllable by varying the current running through the coil. This causes the valve to be partially opened or closed thereby controlling a flow or a level of liquid in a system.
(Here we go again, the ‘Thumbs Down Merchant’ has the correct explantion but, he doesn’t want to share it. (Unless of course they’re being given in order to try to favour another answerer).
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good resource for basic functions of valves etc. http://www.amazon.com/Fundamental-Refrigeration-George-Gunter/dp/1930044232/ref=pd_bbs_sr_1/105-4174690-7409205?ie=UTF8&s=books&qid=1190424672&sr=8-1
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