Hi everybody'

please could tell me what is the different between normally open Solenoid valve and normally close which it is using for instrument air to the pneumatic? and how many port for each one of them. in addition what is the function of tripped relay for double acting control valve?

Thanx

 

Hi,

Normally open solenoid will be in open position if the coil is not energized and will close if it energize. NC coil is vice versa.

 

As the previous poster said the normal position is without power applied. Usually a 3 port solenoid is used when open it connects air supply to valve, when closed it blocks air supply and vents any air in the pneumatics to atmosphere

I'm not certain what you mean by "tripped relay for double acting control valve" Sometimes I have used a pneumatic relay to vent a control valve actuator very quickly. These have much larger ports than the solenoid, they are usually very simple devices that mount between the solenoid and valve actuator. When the solenoid opens the diaphragm in the relay opens a large port to atmosphere venting the actuator very quickly.

I hope that helps
Roy

 

I mean relay for double acting piston valve