On-off pneumatic actuator


Thread Starter

Bijan Rahimi

How can i install two solenoids on one on-off pneumatic actuator (ball valve's actuator)? We require 2 solenoids on each actuator, one is related to dcs system and other is related to esd system.

bob peterson

Try this.

Air pressure to ESD solenoid valve.

Output of ESD valve to pressure port on DCS valve.

Output of DCS valve to process valve.

That way if either solenoid valve shuts off the air signal to the process valve is removed and the valve goes to its fail position.

Install 2 solenoids in series. first install esd solenoid and then DCS operated solenoid. Output of esd operated solenoid is connected to the input of DCS solenoid & output of DCS solenoid is connected to valve actuator. This arrangement is for emergency shutdown condition.
Tushar... your approach reduces the probability of output success, doubles the probability of output circuit failure, and also doubles the probability of an unwarranted (false) trip!

The above comments are based on my interpretation of your explanation. If you want a more accurate Probabilistic Risk Assessment (PRA) contact me off list!

Regards, Phil Corso (cepsicon[at]aol[dot]com)