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VALVES
Manual operation of poppet valves
The devices used to manually control the valve are categorised as
bistable
or
monostable
depending on the
functionwithin the circuit. The light switch, and the doorbell of the house, are two exampleswhich illustrate these
two types of devices: the first is bistable as it keeps the position of the light on or off; the second is monostable
because it allows the bell to ring only when pressing the button.
Manual Operation:
Figure 7
Monostable push button operator, spring return.
The force transmitted by the push button depresses the poppet plunger, this allows the passage of air if the valve
is NC type or its interruption if NO and this will continue as long as the push button is pressed. The repositioning
is performed by a springwithin the valvewhich releases the key.
BUTTON
MONOSTABLE
OPERATION
SYMBOL
SPRINGRETURN
COMMAND
Fig. 7
Figure 8
Monostable lever operator, spring return.
The valve is operated by moving the lever through its arc of movement. The operator must hold the lever in the
operating position for the duration of the action; this achieves the passage of compressed air if the valve is NC or
its interruptionNO.When the lever is released, a spring will return the valve to its initial position. The valve is of
themonostable if type.
LEVER
MONOSTABLE
OPERATION
SYMBOL
SPRINGRETURN
COMMAND
Fig. 8
Figure 9
Lever control, bistable operation, manual repositioning.
The valve is operated by moving the lever throughout its arc of movement, once the end position is reached, the
operator may release the lever, this allows the passage of the compressed air if the valve is NC or its interruption
if NO. The repositioning is performedmanually by returning the lever to the initial position.
LEVER
BISTABLE
OPERATION
MANUAL
REPOSITIONING
SYMBOL
COMMAND
Fig. 9
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VALVES