Programmable lodgic question

[Creetin]

I had a melt down in my ca reactor. My effluent gotten plugged, and ph had shut off but with a ph of 6.5 recycling thru the reactor it had a meltdown even with no co2 entering the system.
I want to use the programmable lodgic to turn off the reactor pump and set an alarm if the co2 solinoid stays off for an hour.
Can this be done?
TIA

 

[Creetin]

After thinking i see my lodgic is flawed thinking this way. The co2 would cycle on off even with the effluent stuck.
I still want to do something like this, But i have to figure out exactly how long it would take to cycle the co2 on and off. I know its longer than normal as i seen it was off for an hour when i was getting ready this morn.
Too bad i did not have monitoring on. Hmm

 

[boboxx]

do you have you ph probe in the reactor or in the tank?

 

[Creetin]

Both. i have 2 ph probes on the profilux

 

[boboxx]

So cant you simply monitor the PH in the reactor and turn off the reactor pump/alarm if PH gets to low in the reactor?

 

[Creetin]

I can, But if the co2 stays a constant 6.5 (What i want to melt thick media) and the effluent line is plugged it will just cont to melt the media, and hense a melt down after a while. The co2 will still go on when the ph in the reacor rises above 6.5, and with the ca/rx recirculating the water inside will cont to melt it.
If i stopped the pump and set an alarm it would stop the meltdown, and warn me.

 

[Creetin]

No body has ever done something similar as a failsafe?
Matthias please help.

 

[redbull99]

I can't really see how you could do this on any system.
You want the pH to be 6.5 in normal use, but only stop Co2 introduction if it remains at 6.5 for a long period... which it would do in normal operation.

Looking at the situation in which it occurs, which is when the effluent outlet blocks. I can't see how can you detect that, without a complicated secondary chamber and level sensors which would equally be prone to blockage. Set a reminder to clean the effluent pipe every week, that's the simplest solution. Without flow detection or pressure detection modules I see no other way.
Steve

 

[Creetin]

I want to turn off pumps if co2 sol stays off for an hour.
Yes periodically check ca/rx, But it only takes 1 day to have a meltdown. 9 times out of 10 it happens on vacation or when you dont look at the reactor for a couple days.

 

[H20ENG]

Creetin,
Did you figure this out? This sounds reasonable enough.

You'd just need to put in the logic to NOT alarm if you had other logic turning off the solenoid- Off while in feed mode, off at night, etc.