Starting pH controller automatically

[OilBoiler]

Hey everyone,

I'm designing a control scheme at which I would like to "start" a pH controller after a level has been reached in the tank, since this is a semi-batch process. I won't be doing the loop drawings for the project, but I need to know whether this is feasible? Because I don't need the pH controller to be acting all the time. I only need it to open or close valves once the tank has filled and then stop acting when the low level is reached.

Thanks in advance!

 

[m777182]

Yes.The most brutal way is to connect you level switch in series with the open/close valve line of you pH controller.But I am sure there is a more ellegant way like command "enable/disable control function".It makes the same things but internally in the controller.
m777182

 

[Rheinhardt]

If the system is hard-wired with no controller{PLC/PC/ect)?? then m777182 would be right otherwise have the programmer of the controller put it into his coding whatever you need, its easier with a controller. Not so messy and keeps your instrument loops basic.

Rheinhardt

 

[ilan7]

I would suggest to monitor the PH at all time. Change the control loop to manual - OFF whenever the level is low, and back to auto when the level is high. You can do that with PLC controller or with a one PH loop controller with high and low level signals. You can also add high and low alarm PH which will be activating at all time.

 

[Murphy625]

If the ph controller retains its settings when power is removed, then just hook its power to a relay. When it powers up, it will should take a few seconds to go threw a self check, and then into normal operation. (depending on the type of controller I guess)

If your processing a batch, how do you keep the PH probes wet all the time?

What is the purpose of the PH controller? Is it actually controlling something like a pump? or just acting as a monitor/alert type of device?