Answer / sam

The design engineers must have had a reason why they
selected to use motorized valves in stead of pneumatic
valves. It might be that they felt the main power is less
likely to fall away than the plant air compressor tripping
and there is no air to operate these valves. It also
sometimes happens that the main instrumentation supply UPS
(24VDC) will trip and the whole plant looses the
instrumentation supply but the main supply is still available.
Also if the main power do fall away there is always the
emergency generators that will kick in and supply emergency
main supply to all the critical systems.
Just for interest they tend to select motorized valves for
safety systems as well like foam, fire pump control valves
and deluge main control valves, most probably for the same
reasons.
Good luck

Answer / rajender

For Very high Pressure Applications motorised valves are
used.

Answer / balaji

TO OBTAIN THE SAME RESULT WE CAN USE THE AIR LOCK RELAY KNOW
Y PEOPLE PREFER ONLY MOV

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