In this article, we have listed the main schematic symbols that are conventionally used by directional control valve.
Two-Way Directional Control Valves:
The two-way valve has two main ports that are called inlet and outlet. When the channel is clogged during the “at rest” condition, it is known as normally closed (NC). The “at rest” box is the one with the flow lines that go to and from it.
The enclosures represent the position of the valves. When the operator moves the valve, it is similar to sliding the upper box so that it can replace the location of the lower box. When the boxes are shifted, flow takes place from the inlet to the outlet. By releasing the palm button, you allow the valve spring to return to the regular stop flow condition.
The two-way valve runs a fluid motor in one single direction, which by itself is a two-way valve that cannot cycle, even with a single acting cylinder.
Three-Way Directional Control Valve:
A three-way valve has three various functioning ports. These ports include the inlet, outlet, and the tank. This variant of the directional control valve supplies the fluid to the actuator; it also allows the fluid to return from it. This type of valve is connected to the single acting; spring returned cylinder that can extend, retract or stop at any place within the stroke. Some three-way valves tend to select fluid paths. Use the spool type valve for this operation. The diverter valve is another flow condition; it sends the fluid in two ways. The number of boxes the valve has determines how many positions are included in it.
Five-Way Directional Control Valves:
Many spool type air valves are available in a five-way configuration because the air that is dispensed usually exhausts in the atmosphere. Hence, the extra exhaust port does not pose a problem.
Many valves use the two exhaust ports for speed control mufflers. Mufflers can make the exhaust runs smoothly and quietly; they also throttle the exhaust, and this controls the cylinder speed in a meter-out circuit.
Moreover, you can use a dual inlet piping to make the sir cylinder operate smoothly. Most air cylinders go from one extreme to another, a two-position, single solenoid, spring return valve is enough for this task. 90% of air circuits use this type of valve. If you want to stop an air cylinder in mid-stroke, then use the three-position valve.
It can be difficult to accurately stop an air cylinder at any place than the end of the stroke. So, when the cylinder moves slowly, a repeated mid-stroke position of plus or minus an inch can be possible. The only problem is that if the load on the cylinder shifts or if there is any slight leak in the piping, it will not hold the position once it stops.