Namur is an acronym for the user association of Automation Technology in the process industries which also serve as a standard for automated valve technology. This standard interfaces for mounting actuators actually keep solenoid and installation cost very down. As a result, the NAMUR solenoid valve is directly connected to the inlet/outlet port of the pneumatic actuator.
The function of the NAMUR solenoid valve is to control the flow of fluids. The valve itself is controlled by an electrical solenoid that closes and opens valves which in turn control the amount of kp-lok.com air to close the valve via a pilot pneumatic actuator. Pneumatic actuators convert energy into compressed air in motion. Solenoids and actuators operate in parallel to control flow amount, flow direction and flow speed. Likewise, the valve operates in a normally closed or normally open position.
The solenoid valve has various configurations, including three directions and four directions. The three-way solenoid valve typically consists of an inlet, an outlet, an outlet and two seats for fluid controls. The four-way solenoid valve uses four or more ports (1 outlet, 2 inlets, 2 seats and 2 exhausts), and is designed to operate a double acting rack and pin actuators.
Principle of design and operation
Pneumatic solenoid valves generally have a coil structure. They consist of aluminum bodies with cylindrical holes. The different ports of the valve are connected to the cylinder. The coil in the cylinder has several seals along its length. By moving the coil back and forward through the cylinder, various connections can be connected or closed. The coil design is very difficult to form a tight seal. Therefore, pneumatic solenoids valves always have very small (but acceptable) internal leaks. With these types of valves, air can flow through the valve in either direction. This is usually called a bidirectional.
The force required to move the coil is relatively small. The effect of air pressure on the required force is limited. In addition, the spring force in a single stabilizing valve is very small. As a result, the solenoid typically consumes little energy. Most valves are pilot operated and therefore require less force of the solenoid valves. Pilot operation (indirect mode) means that the valve uses air pressure to actuate the valve, and that the air pressure is controlled by the solenoid. With this design, the transmission force of the solenoid must be much less than the force transmitted by the air pressure. The valve may be externally or internally piloted. The internally piloted valve uses the inlet pressure to actuate the valve, and the external pilot valve uses a separate channel for the piloted operation. Internal piloted valves generally require a constant pressure difference of 0.1 to 1.5 bar to operate. If this pressure is too low, the valve will not switch even if the solenoid valve is activated. Internal piloted valves are not suitable for low pressure or vacuum applications.
The technician may ask if the pneumatic solenoid valve can be used for other fluids such asoilorwater. The truth answer is that it is not usually recommended. Many pneumatic solenoids are internally controlled to minimize the amount of air needed to operate the valve. For most applications, a slight air leak in the environment is acceptable, but not for oil, water or other media. In addition, the material of the valve is usually optimized for the use with air. Normally the valves prepared with aluminum parts and HNBR or NBR seals. Media other than air can cause corrosion and other chemical reactions that can affect the life duration of the valve.