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VALVES
B
G
P
A
P
P
A
P
P
A
P
1
2
3
Fig. 51
Logic function AND
It has three pneumatic connections: two inlets and one outlet.
Togeneratea signal at theoutlet, it isnecessary tohave thecontinuouspresenceof pressure inbothof the two inlets.
They need not necessarily be pressed simultaneously.
It is not sufficient to be used alone as a “Two hand control valve”.
Figure 52
Pos. 1
:
presence of inlet
P
on the upper side only.
The pneumatic inlet
P
pushes the stem
C
downwards and its seals, acting on the orifice located on the insert,
closing the passage of this inlet towards outlet
A
. In the opposite direction any pressure on outlet
A
can exhaust
through the lower inlet
P
.
Pos. 2
:
presence of both upper and lower inlets
P
.
With the stem in the position determined by the previous pilot signal, the second pilot signal is free to move
towards outlet
A
. The presence of outlet
A
is indicated by the extended indicator
D
. In the presence of two inlets
with varying pressures
P
, the outlet
A
is always the signal with lower pressure.
Pos. 3
:
presence of inlet
P
on the lower side only.
The pneumatic inlet
P
lifts the
C
and its seals, acting on the orifice located on the insert closing the passage of this
inlet towards outlet
A
. Any pressure on outlet
A
can exhaust through the upper inlet
P
. The Indicator
D
stem, due
to the spring is in the rest position.
D
C
P
A
P
P
A
P
P
A
P
1
2
3
Fig. 52
Logic functionMemory
The logic functionMemory supplies a signal to the pneumatic sections of the circuit depending on the pneumatic
command received and should remain in the position determined by the last pilot signal. Its operation is identical
to that of a bistable pneumatically operated 5/2-way valve, with two differences:
• reduced dimensions, as in the signal processing valves a high flow rate is not required;
• presence of themanual override.
Figure 53
Pos. A
: pilot signal 12.
In thepresenceof pilot signal 12 the grey spoolmoves to the right allowing thepassageof C/A from inlet 1 tooutlet
2 and from outlet 4 to exhaust 5. The spool pushes the right manual override outwards.
Pos. B
: absence of pilot signals.
As by definition this valve function memorizes the position determined by the last pilot received. The state does
not change.
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