Camozzi Pneumatics Manual

VALVES

The 2/2-way NO or NC valves are generally used in applications that involve blowing operations, or tank filling,

closing a flow, etc. Aesthetically they do not present any substantial differences to the 3/2-way valves apart from

the absence of connection of the exhaust 3 and the different connection points.

2/2-way NO solenoid valve

(2-way, 2-position, Normally Open)

Figure 28

Rest position, electrical contact open, absence of electrical energy.

Pos. A

: to reduce the number of components, the body of the 3/2-way version is typically used; however the port

that would have been closed is plugged. The conical spring pushes the mobile plunger and its seal against the

orifice connected to the plugged port.

Pos. B

: under the influence of the conical spring, the upper part of the mobile plunger and its seal are detached

from the fixed plunger and its orifice, which enables the connection between inlet 1 and outlet 2.

Fig. 28

Figure 29

The electrical contact is closed, there is passage of electrical energy, voltage is supplied to the solenoid.

Pos. C

: a current flows through the solenoid generating amagnetic field that attracts themobile plunger upwards.

The conical spring compresses and the seal is detached from the orifice.

Pos. D

: the surface of the upper part of the mobile plunger is now in contact with the lower surface of the fixed

plunger, the seal closes the passage between inlet 1 and outlet 2.

Fig. 29

Regardless of the type of actuation, the operation of the poppet valve depends on the pressure and the size of the

orifice under the poppet on the inlet side. Themobile plunger, previously analyzed, represents the poppet, which

via a seal and a conical spring keeps the orifice closed. In this state, the conical spring is dimensioned in such a

way that it overcomes the thrust that the pressure of the compressed air generates on the surface of the plunger

in contact with the orifice. As the pulling force of the solenoid that moves themobile plunger “is considered to be

constant”, there is a proportional relationship between pressure and diameter of the orifice.With high pressure the

diameter of the orificewill have to be smaller, with low pressure the diameter may be larger.

The 2/2-way NC valves are typically used for blowing operations such as taps where it’s necessary for the

passage areas to have greater diameters and high pressure. These requirements are achieved due to a different

construction, the seal of themobile plunger and different flow directions of the compressed air.

105

CAMOZZI

VALVES