Tuttnauer 2301006, Operation & Maintenance Manual

Page: 13 / 122

Page 8 of 117 pages
2.4 The Pneumatic Control System
The control of the pneumatic valves is done through compressed air, as described
below:
The pneumatic valves are air-air control type, fitted with two commands, an
opening command received through solenoid valve at a pressure of 6 bars - output
by the control system and a permanent closing command at a pressure of 3 bars,
connected to all valves.
The pneumatic control system is built as follows (refer to drawing on the next
page).
The incoming compressed air supply at a pressure of 7-8 bars is set by means of
a pressure regulator at 6 bars and transmitted to the entrance of the pilot solenoid
valve battery.
The solenoid valve battery is mounted on a manifold branch base, through which
all the solenoids are connected to the compressed air supply.
At the output side of the manifold branch, a pressure regulator at 3 bars sets the
compressed air.
As long as a pneumatic valve does not receive from the control system an opening
command the close command which is permanently present will determine the
shut-off position of the valve.
When an open command at 6 bars reaches a pneumatic valve, it overcomes the
opposite close command at 3 bars, and sets up the valve in position open.
A non-return valve mounted between the outlet side of the manifold branch and
the pressure reducer prevents the flow of air from the air reservoir to the solenoid
battery.
One safety measure is provided, a pneumatic control three-way, two-position
steam activated air returned valve
,
to prevent the possibility of opening the door
when pressure is introduced in the chamber.