types of distributors

 types of distributors

General presentation

Distributors are the most commonly used accessories in pneumatic circuits, they
correspond to switches, contactors and relays of electrical circuits. A
distributor is defined by the following :

• position number ;
• number of orifices or channels ;
•  internal construction(drawer, valve, other).

Drawer dispensers usually have two or three positions while the
clap dispensers only count two.
Each rectangle or square corresponds to a position of the dispenser. Inside
each square, arrows indicate the direction of fluid circulation for each of the
distributor positions.

The different models of distributors are represented using symbols. Symbol
representing the distributor indicates the number of its ports, its switching positions
and its control mode.
"Zero" position means, in the case of recall distributors, the position that the
moving parts occupy when the dispenser is not operated.
"Rest" position (or " initial position ") means the position occupied by the
moving parts of the distributor after installation and installation
pressure or, if applicable, under electrical voltage. This is the position by which
starts the switching program.
Usually the orifices are identified by letters. Thus, according to ISO 1219, the
orifices of a dispenser are identified as follows :

• Supply pressure (power source) : P
•  Output or use (Work): A, B, C…
•  Exhaust (exhaust free l air): R, S, T…
•  Control : Z, Y, X…

contains a list of symbols of the most common distributors

• Each dispenser can be ordered by various processes and it has a means of recall : the control method constitutes the actuation mode and is drawn, by

convention, to the left of the distributor symbol ;

•  the recall means constitutes the deactivation mode of the dispenser and is drawn,

by convention, to the right of the symbol.
In addition, two main classes of distributors are distinguished according to the number of
stable positions they possess :
- Monostable: has only one stable position, that of rest. Mode
must be permanently activated for the entire duration of the actuation
distributor. This is the case with a push-button and spring-return model.
- Bistable: has two stable states, which means that an actuation
momentary or a single pulse is used to switch the distributor. It is also said
that a bistable dispenser acts as a memory, because it has the ability to preserve his position. This is the case of a model equipped with a pneumatic control of each
side.

The construction characteristics of the dispensers are decisive for longevity,
response time, control mode, connection types and
the clutter.
Types of construction of distributors :

•  Valve dispensers :

* ball dispensers ;
* flat seat dispensers (valve or disc)) ;

•  Drawer dispensers :

* longitudinal drawer dispensers ;
* flat longitudinal drawer dispensers ;
* turntable dispensers.

A. distributors 2/2

The distributor 2/2  has two openings and two positions (open, closed).On

this distributor, there is no exhaust in the closed position. The type of

the most commonly encountered construction is the ball dispenser.

The 2/2 dispenser is rarely used in a pneumatic circuit. We use it mostly

to open or close a power line. A distributor may take different

position. It is said to be "open" or "closed". His condition at the rest position on

characterized as "normally open" or "normally closed".

B. distributors 3/2

The 3/2 distributors allow the activation or resetting of the signals. Distributor

3/2 has 3 ports and 2 switching positions. The third orifice 3 (R) serves to

exhaust the signal path.

b. 1 ball dispensers3/2

An action on the pusher of the dispenser causes the ball to take off from its seat. It is necessary for this

defeat the force of the return spring and the force of the present pressure. At the actuated state,

the ports 1 (P) and 2 (A) are connected and the dispenser thus switched releases the flow. In this

the distributor is controlled either manually or mechanically. Force

operation depends on the supply pressure and friction inside the

distributor. The size of the dispenser is thus limited. Ball dispensers are from

simple and compact design.

b. 2  Valve dispensers 3/2

b. 3  drawer dispensers 3/2

The drawer model is very versatile, because by simply reversing the connection of the orifices, a 3/2 n distributor is obtained .O.

The use of 3/2 dispensers is widespread. It can be used to directly actuate cylinders or motors, or simply to provide an air pulse necessary to control another distributor. 3/2 dispensers can be manually operated, mechanical, electric or pneumatic. The choice of the order mode is dictated by the specifications. The distributor 3/2 with pneumatic control (fig. 9 A, B and c) is operated by means of a pneumatic signal sent to the input 12 (Z). Usually it is with a return spring. A pneumatic control distributor may be used as a pre-actuator in the case of indirect control.

C. Distributors 4/2

The 4/2 dispenser has four orifices and two positions. It fills the same

function that a combination of two dispensers 3/2, one of the dispensers to be

closed at rest and the other open at rest.

flat seat Distributor 4/2

The two pushbuttons  are actuated simultaneously to first close the pushbuttons.

orifices 1(P) to 2(B) and 4(A) to 3(R). By continuing to press through the pushbuttons

on the valves and on the Springs is obtained the reopening of the orifices 1(P) to 2 (B) and

4 (A) to 3 (R).

The distributor has an exhaust port without overlap; it is brought back into

initial position by a return spring. This distributor is used for cylinder control

double effect.

There are 4/2 distributors with single pneumatic control and return spring

(Pneumatic distributor) and double-operated pneumatic (pulse distributor), with

roller with steering and with flat or cylindrical drawer.

drawer Distributor 4/2

D. distributors 4/3

The 4/3 distributor has 4 ports and 3 positions. The Rotary tray dispenser 

is an example. This dispenser is usually manual or pedal operated.

An action on the control causes the rotation of two trays that connect the

pipelines between them.

E. Distributors 5/2

The 5/2 dispenser has five orifices and two positions . It is mainly used

for the control of cylinders. The longitudinal drawer dispenser is an example of this.