A direct acting solenoid valve is designed in such a way that the ferromagnetic armature core within the core tube controlled by the electro magnet is directly controlling the flow or media through the valve. In the case of a miniature or compact M5, 1/8", 1/4", 3/8" or 1/2" solenoid valve with a smaller orifice or flow path, the armature itself rests against the sealing face.
In the case of a 2 way normally closed miniature solenoid valve the first picture on the right shows a miniature 2/2 way normally closed solenoid valve in the closed position. The armature (Green) s sealing against the orifice preventing the flow of media (Blue) from inlet port 1 to outlet port 2.
The second picture on the right / below shows the same 2-way compact solenoid valve but in the energised open position. The electro magnet (Grey) is energised generating a magnetic field pulling the armature (Green) up and away from the sealing face to allow the flow of media (blue) from inlet port 1 through to outlet port 2.
In the case of a 2/2 way normally open direct acting solenoid valve the function is in reverse, in that when energised the armature seals preventing flow and at rest is held lifted into the open position.
In the case of a 3/2 way miniature direct acting solenoid valve it is a little more complicated as there are 3 ports and the armature can seal from both ends (top and bottom).
For example the first picture on the right / below shows a 3/2 way normally closed solenoid valve at rest, the armature seals against the orifice blocking the inlet port 1, but pressure from the outlet port 2 can vent past through to the third exhaust port 3.
The second picture on the right shows the same 3/2 way direct acting solenoid valve in the energised position. The coil (Grey) has generated a magnetic field to lift the armature away from the inlet port 1 sealing orifice allowing flow from inlet port 1 through to outlet port 2 and at the same time sealing against the exhaust port 3 to prevent flow in this direction.
3/2 way valves can be supplied normally open i.e. inlet port 1 open to port 2 with port 3 closed, when powered port 1 closed and port 2 open to port 3 OR universal function so that inlet port can be ports 1, 2 or 3 with bi-directional flow (flow in either direction) control.
3/2 way direct acting universal function solenoid valves means that the media flow can be both directions and the valve can be used 3 way universal solenoid valveas normally closed, normally open or diverting function. To achieve each option no modification to the valve is required it is achieved by simply connecting the inlet supply to either of the three ports available.
The picture on the right / below shows a typical 3 port 2 position universal solenoid valve, with three ports marked 1, 2 and 3 with standard IP65 electro magnetic DIN43650A coil and electrical DIN connector.
Normally Closed Function: Pipe pressure inlet into port 3, port 2 is outlet with port 1 exhaust.
Normally Open Function: Pipe pressure inlet into port 1, port 2 is outlet with port 3 exhaust.
Diverting Function: Pipe pressure inlet into port 2, port 2 and 3 are both outlets.