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can someone tell me some advantages of pneumatic controllers versus electrical controllers? i can't seem to find any answer on the web it only shows up all this complicated stuff. i'm not that good at process tech yet...

Hi,

The only advantages I see is, it being a pneumatic controller, it is safe to put it in hazardous area, close to your process, so in situ tuning of process parameters can be done.

Disadvantages could be many many, a few are:
1. Moving parts - more maintenance
2. Pneumatic signal travels slow
3. No autotuning or any complex control
4. Manual adjustment is required
5. May drift after continuous operation
6. More costly to operate - compressed air is energy, more maitenance

Regards,

C. Potdar

To add to C Potdar,

Sometimes you see pneumatic controllers running on other than air, I have seen them on natural gas. Pneumatics is also good for local control in wet areas e.g. flotation level control in mining. Even so I have not purchased one in over 20 years. Most electronic controller output signals still convert back to pneumatics at the control valve.

Roy

Pneumatic controls are not subject to damage from electromagnetic pulse (EMP) generated by atomic weapons.

Pneumatic actuators are usually cheap, simple and reliable. If You need move something or latch, they are very often the only option.