5/2-way and 4/2-way pneumatic valves
The 5/2-way pneumatic valve has five connection ports and two states. It has one pressure port (P,1), two ports (A,2) and (B,4) that connect to the device that needs to be controlled, and two exhaust ports (EA,3) and (EB,5). The two states of the valve are:
- Pressure port (P,1) connects to port (A,2), while port (B,4)
ventsthrough exhaust port (EB,5)
- Pressure port (P,1) connects to
port(B,4), while port (A,2) ventsthrough port (EA,3).
Video: How to use a pneumatic solenoid valve by Tameson
Different manufacturers use different port designations. There is also a standard designation: ISO-1210-1. This standard we aim to maintain in our articles as much as possible. The ISO standard uses numbers to designate the different ports. Some manufacturers, however, use letters to somewhat clarify the port designations.
In the example, ISO port 1 is also designated with a letter P from 'pressure', which is the connecting point for the pressure line. The outlet ports (or working ports) with the ISO designations 2 and 4 are alternatively designated with the letters A and B. The corresponding exhaust ports have the ISO designation numbers 3 and 5. The alternative letter designations of these ports are respectively EA and EB, which means 'exhaust from
Valve symbol of a mono-stable 5/2-way valve with ISO and alternative port designation
The 4/2-way pneumatic valve has four connection ports and two states. The difference between the two valve types is the number of exhaust ports:
- A 5/2-way pneumatic valve has two independent exhaust ports
- A 4/2-way valve has only one common exhaust port
Valve symbol of a mono-stable 4/2-way valve with ISO and alternative port designation
This means that both port (A,2) and (B,4) connect to
The valves can be mono-stable or bi-stable. Mono-stable 5/2-way valves return to their rest position when they are not actuated. The valve returns to its rest position by means of a spring. This means that mono-stable valves require constant actuation (pneumatic, electric or manual) to stay in the actuated position. Bi-stable 5/2-way valves keep their position during power
The following circuit functions are possible:
- 5/2-way mono-stable
- 5/2-way bi-stable
- 4/2-way mono-stable
- 4/2-way bi-stable
5/2- and 4/2-way pneumatic valves can be actuated by different means:
- Electrically (solenoid valve)
The circuit function and actuation of the valve can be shown by a symbol. The circuit function symbols for both 4/2-way and 5/2-way solenoid valves are given below.
Circuit function symbols of 4/2 and 5/2-way pneumatic valves
Although the basic function remains the same, pneumatic 5/2-way valves are available in uncountable design variations with regards to size, material, color, connection interfaces, etc. This is necessary to meet a wide range of requirements, such as medical use, food processing, dusty environments, explosive environments etc.
Most 5/2-way valves have a movable spool with seals along the length in a cylinder. The valve ports connect to this central cylinder. By moving the spool through the cylinder, the valve ports are connected or blocked. Furthermore, the valve can be
Many 5/2-way valve types are available with manual override, or even with a lock mechanism. The benefits of the lock mechanism can be seen during maintenance – the valve keeps the designated position until the lock is released – so the actuated pneumatic elements, such as cylinders or grippers retain their positions. One possible use for the manual override is testing the system; the valve doesn’t need to be electrically energized to be actuated. To switch the valve, it is enough to push the override button. A disadvantage of a lock mechanism is that operators might forget to remove the lock.
While selecting a solenoid valve, the type of electrical connector needs to be considered. Some manufacturers have a wide range of connector designs or use standard DIN connectors, such as DIN43650 type A,
Some 5/2-way valves are available with a NAMUR housing. NAMUR is a widely used interface standard to mount a control valve directly onto an actuator. By using a NAMUR valve, the number of fittings and tubing can be reduced.
Some valves can be mounted on a manifold. This is an easy way to group multiple pneumatic valves and save space,
A 5/2-way valve can be used as a 3/2-way valve, by blocking one inlet and one outlet (A-EA or B-EB) port. With two 3/2-way mono-stable valves, it is possible to build a 5/2-way bi-stable valve.
5/2-way valves are used to actuate double acting pneumatic actuators, such as cylinders, rodless cylinders, grippers and rotary actuators. Double acting actuators require compressed air to move in both directions. To decide whether a
The following information is needed to decide which valve can be used:
- How many actuators are in the system?
- How many
I/O ports areavailable on the PLC?
- Actuator’s positions
- Normal working conditions
- Safety requirements
Schematic representation of a double acting cylinder with adjustable end-position cushioning at both ends, actuated by a 5/2-way mono-stable valve
The number of actuators determines the required number of valves: each actuator or group of actuators needs its own control valve. The PLC limits the number of coils that can be energized. Mono-stable valves (with one solenoid coil) require less wiring and PLC outputs than bi-stable valves (with two solenoid coils). Some manifolds have internal wiring and have one connector that connects to all valves, for
The choice between mono-stable and bi-stable valves is often motivated by safety requirements. In some machine designs, to prevent machine damage or injuries, it might be desired that the actuator returns to the base position during power loss. In such
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