Reactor Peristaltic Pump Question

Carl Salamone · Nov 20, 2018

Hi All,

I'm setting my reactor up to use a Masterflex style pump to push water through the reactor. I have an Apex controlling gas to the reactor based on reactor ph. I have it set up with the pump pushing water in and then an open/unrestricted line on the effluent output. The pump works great when the CO2 is turned off, but as soon as the gas turns on, gas displaces water inside the reactor chamber and everything goes downhill. The CO2 gas upsets the reactor's internal circulation pump and then CO2 gas gets dumped out through the effluent line, and causes a pH crash in the tank.

Can anyone tell me what I'm doing wrong please?

Thanks,

CS

LobsterOfJustice · Nov 20, 2018

It sounds like your CO2 flow rate might just be too high? What is your bubble rate in the bubble counter when the solenoid is open?

Carl Salamone · Nov 20, 2018

LobsterOfJustice said:
It sounds like your CO2 flow rate might just be too high? What is your bubble rate in the bubble counter when the solenoid is open?

I haven't been counting bubbles, just running the gas at about 0.5 PSI, letting the Apex control the gas solenoid as needed. Do you have any suggestions for a bubble count when paired with an Apex control?

Breadman03 · Nov 20, 2018

This thread might have some insights for you.

ca1ore · Nov 20, 2018

Picture would help to diagnose

Carl Salamone · Nov 20, 2018

It's made by Reeftek. Right now the reactor is receiving water from a pressurized manifold. I use a combination of the black handled needle valve and the john guest quarter turn fitting to adjust the effluent output. The CO2 is controlled by a solenoid that is triggered by apex. I'm not using a bubble counter for CO2, it just gets about 1/2 PSI from the low pressure regulator and that has seemed to work ok. My problem is that I routinely get clogs in the needle valve and have a hard time finely tuning the output.

So, I'm trying to make the change to a Masterflex style pump (Premia 75 - It's a diaphragm pump, but one designed for 24/7 operation at much larger back pressures than reactor pressure). Anyhow, when I use the Premia pump to push water through the reactor, it works great until the gas kicks on. I guess going back to bubble counting will probably solve the issue, but then what's the point of using the Apex solenoid control? Hoping I can make both the solenoid control and this Premia pump work together.

Thanks.

LobsterOfJustice · Nov 21, 2018

Solenoids fail. Solenoids are not meant to replace a bubble counter. The bubble counter lets you know the rate of flow (which I think is your issue) and it should be treated as a backup/failsafe, the CO2 bubble rate should still be appropriately tuned.

scuzy · Nov 21, 2018

You do adjust the co2 regulator to put out a specific amount of gas. If you let it run wide open that's too much co2 being let out ?

Carl Salamone · Nov 23, 2018

Thanks guys. I bought a new low pressure side valve and combined bubble counting with the solenoid control. The continuous duty pump is working great now. Pretty neat that you can see a change in solenoid cycling when I turned down the flow of the pump.

scuzy · Nov 23, 2018

What you really want is adjust the bubble count to a point where it keeps the solenoid open at constant pH in reactor. Like your pH graph is a constant straight line.

Carl Salamone · Nov 23, 2018

My solenoid is fairly old and when left on for long periods of time it gets pretty hot. So for now at least, the cycling is ok. Maybe once I dial in the reactor it might make sense to replace the solenoid and try to tune the gas more appropriately.

Thanks!