Pneumatic Positioner
YT-1200 series
Product Manual
Ver. 1.18
20
3
principle of positioner movement
3.1
Linear Positioner
Fig. 3-1: Linear positioner with an actuator
When INPUT SIGNAL PRESSURE increases to open the valve,
①
the bellows stretches and pushes
②
the flapper to the opposite side of
③
the nozzle. The gap between
③
the nozzle and
②
the flapper
becomes wider and from inner part of
④
the pilot, air inside
⑨
the chamber is exhausted through
③
the nozzle. Due to this effect
⑤
the spool moves to the right. Then,
⑦
the seat which was blocked
by
⑧
the poppet pushes the poppet away and supplied pressure (air) goes through
⑦
the seat and
OUT1 Port and enters into
⑩
the chamber of the actuator. Then
⑩
chamber’s pressure will increase
and when there is enough pressure inside the chamber to push
⑪
the actuator’s spring,
⑫
actuator’s
stem will start to go down and through the feedback lever, stem’s linear motion will be converted to
⑭
span lever’s rotary motion. This
⑭
span lever’s rotary motion will then once again rotate
⑮
the
span and pulls
the spring. When the valve’s position reaches to given input signal pressure,
⑯
span
spring’s pulling force and force of
①
bellows will be balanced and move
②
the flapper back its original
position to reduce the gap between
③
the nozzle. The amount of air being exhausted through
③
the
nozzle will reduce and
⑨
the chamber pressure will increase again.
⑤
Spool will move back to its
original position on the left and
⑧
the poppet will also move in same direction blocking
⑦
the seat to
stop the air coming into the
⑩
chamber through the SUPPLY. As a result, the actuator will stop
operating and the positioner will return to its normal condition.
Содержание YT-1200 Series
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