Festo CPA-SC Series, Manual

Page: 90 / 140

4. Commissioning
4−6
Festo P.BE−CPASC−EN en 0808c
The pilot air must reach a pressure of 3
Ū
8 bar as soon as it
is switched on, otherwise, there is no guarantee that the valve
will switch directly (see diagram).
If the pressure is less than 3 bar, there may be a delay before
the valve is switched, in spite of an electric signal being
present. The slow increase in pressure of the complete supply
does not then affect the actuator. The actuator would react
suddenly (e.g. a cylinder would extend or retract suddenly,
depending on the valve function).
1
4 2
5 3
14 12
1
2
1
12/14
12/14
3
82/84
2
1
Externally supplied pilot air (3 to 8 bar), branched in
front of the safety start−up valve
2
Safety start−up valve (slow build up in pressure of
complete supply)
Fig.4/1: Example of valve−cylinder combination with slow
increase in pressure of the complete supply