133 / 218
VALVES
Pressure switches
To enable a system to operate properly, the pressure needs to reach a value suitable for the requirements, and
only in this state the cyclemay begin. Pressure switches are thereby employed to ensure this value remainswithin
the allowed range.
The pressure switch is a component that is connected to the source of the compressed air, and uses that pressure
to commutate an electrical switch.
Themost common are:
•with
Normally Closed contact (NC)
•with
Normally Open contact (NO)
•with
Exchange contact (NC
and
NO)
Thepressure switch canbe regulated toadjust the switching point of the switch to thenecessary pressure value. The
adjustment ismade bymeans of a regulation screw, which, by placing a load on a spring, acts on a diaphragm, and
so opposes the thrust force from the air.
Figure 67
NCModel
: in the absence of pressure the switching elements are in contact with each other closing the electric
circuit so that the signal is present. Upon applying pressure, the switching elements separate from each other and
the electric circuit is interrupted.
Fig. 67
Figure 68
NOModel
: in the absence of pressure on the diaphragm, the switching elements have no contact with each other
and the electric circuit is interrupted. In applying pressure on the diaphragm, the electrical contact closes the
circuit, enabling the signal.
Fig. 68
The
Exchange contact Model
is similar to previous models, the only difference is that this type of switch is
equippedwith both
NC
and
NO
contact.
4
131
CAMOZZI
>
VALVES