Directional control valves belong to the large family of valves or solenoid valves. They have the particularity of offering a wide range of functions, generally allowing them to control pneumatic actuators.
Valves can be operated mechanically, pneumatically or most often electrically. They are available in sizes from M7 to G3/4", in 3/2, 5/2, 5/3, monostable or bistable versions. A distinction must also be made between individual valves and valve terminals.
With the help of selected partners, Elneo offers a wide range of valves, dispenser terminals and related services. Standard dispensers are available from stock and can be delivered within 24 hours, but it is also possible to configure customised dispenser terminals according to your needs.
Our experts are at your side to guide you in the selection of the ideal equipment and accessories for an optimal solution. Finally, we offer pneumatic diagrams and CAD files to design offices.
The main valve functions encountered are
A 3/2-way valve has three ports: an inlet (1), an outlet (2) and an exhaust (3). It is always monostable with a mechanical or pneumatic spring return. It is used to control a single-acting actuator.
A 5/2 way valve has 5 ports: one inlet (1), two outlets (2 and 4) and two exhausts (3 and 5); and 2 positions. It can be monostable, with a spring return, or bistable, without return to the initial position. It can be used to control a double-acting actuator.
A 5/3 valve has 5 ports: one inlet (1), two outlets (2 and 4) and two exhausts (3 and 5); and 3 positions. It is the centre position that varies according to the need: centre closed, centre open or centre exhausted. It is always bistable, with spring return to the centre position. It allows to drive a double acting actuator with intermediate positions.
What types of piloting are possible?
The most common type of valve used is the electrically controlled valve. In this case, solenoid coils are used to operate the valve spool. The most common voltages are 24 VDC and 230 VAC.
The valves can be connected individually when only a few coils are to be connected, whether they are mounted in a battery or insulated. Different types and sizes of connectors are available for different applications.
For ease of maintenance and electrical connection during installation, we recommend the use of multi-pin valve terminals with Sub-D25 connectors for quick connection.
The valve terminals can be connected to a network and controlled via a Profinet, Profibus, IO-Link, EtherCAD or other fieldbus. This allows maximum flexibility in connection and allows all input and output signals to be managed as close to the application as possible, for example for limit switches.
Note: All electrically operated valves require pneumatic assistance to operate correctly. This assistance can be internal or external.
The majority of valves are internally assisted, the pressure at the valve inlet is used for piloting. If the minimum required inlet pressure is not sufficient, the valve spool will remain in place despite the presence of the electrical signal or forced manual pilot.
With external pilot air, it will operate regardless of the inlet pressure, as long as the pilot pressure is sufficient. This requires additional ports on the valves.
In the past, manually or mechanically operated valves were widely used in industry. Today, with the advent of sensors and electronics, they are gradually being replaced by electrical solutions. However, we still offer a varied and recently updated range of lever, pedal, mechanical limit switches and push button valves.
In addition, pneumatically actuated valves can be found where compressed air pulses are used as the signal. The signal pressure is used to switch the valve position. Logically, they have additional, smaller ports for the connection of the pneumatic signal.
What types of set-ups are encountered ?
Depending on the number of valves, universal valves can be mounted individually, in a battery or on a terminal. There are also spool valves with a standardised installation layout that allow interchangeability, regardless of the manufacturer.
NAMUR faceplate valves according to VDI/VDE3845 are mounted directly on the process valve actuators. The 3/2 and 5/2 function are provided by the same valve by means of an adaptable seal.
ISO 15407-1 and ISO 5599-1 standardised spool valves are mounted on standardised subbases and allow interchangeability with any manufacturer. The subbases can be individual or assembled in a battery. These valves are of very robust construction and are often used for higher flow rates.
ISO faceplate valves are available in different sizes: ISO 15407-1 size 01 and 02, ISO 5599-1 size 1, 2 and 3.
All valve functions and control types are also available in ISO versions. Many accessories can also be combined. Depending on the options and accessories selected, some functions may not be interchangeable between brands. This is the case, for example, with valve terminals, where each manufacturer has its own system.
Always ask one of our specialists to guide you in your choices and select the most suitable equipment for your needs.
Elneo is able to provide you with all of these pneumatic valves and more, thanks to recognised partners who are focused on quality and innovation. Our key partner for this product range is Festo.