How to control pH levels continuously?

[davidd31415]

Hi:

I'd like to continuously control the pH level of a tank of salt water. I'm looking for insight into pH sensors, specifically if all require calibration before each use.

My set point will be 6-7 pH.

http://www.aquamerik.com/catalogue/produits.cgi?category=analyseeau_controleursphindus&lg=eng

This appears to me to be a pH controller that will work continuously. Does anyone know how this might work?

Thanks,

David

 

[JLSeagull]

Several pH sensor manufacturers have tutorials on their web site. One manufacturer has a plug-and-play digital probe. Most require calibration before the first use after replacing the sensor. The digital sensor may eliminate this issue. Calibration is normally done using buffer solutions. Some manufacturers include ABB, Endress Hauser, Hach, Rosemount, Yokogawa etc. Related sensors for your application may include conductivity.

 

[bimr]

You are better off going with one of the name brands that JLSeagull is referring to.

The choice of sensor is probably more critical than the monitor that is used. You have to select a sensor that is appropriate for your application. Without knowing more about your application, you should probably plan on cleaning the end of you sensor once per week.

http://www.us.endress.com/eh/produc.../contentview/032CBE7118B6187AC1256CF3002A4C58

If you want to measure the pH in a tank, you will also have to have some type of mixer in the tank to homogenize the solution. Otherwise, you pH readings may be off.

 

[davidd31415]

Thanks for the link. Are there technologies other than Endress + Hauser's Memosens that can be used for constant pH monitoring?

If someone could point me to information regarding the advantages and disadvantages of different sensor technologies, I'd appreciate it; specifically:

Gel vs. Liquid Filled
Ceramic vs. Teflon diaphragms
Open apertures and salt reservoirs