waste water PH control

Join Date
May 2007
Location
giza
Posts
153
Hello guys

Iam working in Washing plant sure washing water PH is very important to us we use only one dosing pump for SODA we change the dosing manually "L/H" we have no any automatic control for PH only by lab test we increase or decrease the dosing

I want to control it by the same way but using PH sensor and dosing pump which I can change the dosing automatically so I searched in this forum and after that I decided to use FU20 pH/ORP Combined Sensor from yokogawa where I want the sensor to measure PH from 2 to 12 and give me a signal 4-20mA I will use in PLC program then change the dosing this process will repeated every 5 mins

my questions
1- is my choice the best or there is a better sensor?
2- I know PH process is not linear so Is my process good or not?
3- from the attached Pics I can not know the terminal of PH signal?

I appreciate your help

PH1.jpg PH2.jpg
 
Last edited:
You only have half the stuff needed for pH measurement.

What you listed is a pH probe only. Its output is NOT compatible with a PLC analog input. Its output is high impedance, requiring a VERY high impedance analog input.

You need a pH analyzer or controller with analog output, or a pH transmitter; any of which connects to the probe and produces an industry standard 4-20mA output.

The reason you are confused about wiring is that the wiring is intended to connect to a compatible pH analyzer/controller/transmitter which has connections labeled to match the probe wiring.

Go search for a pH analyzer/controller/transmitter from which to get your signal.
 
many thanks Dan and Oceansoul

I will use FU20 pH/ORP and EXAxt PH450 4-Wire Analyzer
Could any one tell me how much the probe and the Analyzer will cost?
 
You're right about pH control being non-linear. How much that influences your logic depends on the range of variation you expect, and on the alkalinity of the water. If you do a search on this site you will find several threads about pH control that may give you some guidance.
 
many thanks Dan and Oceansoul

I will use FU20 pH/ORP and EXAxt PH450 4-Wire Analyzer
Could any one tell me how much the probe and the Analyzer will cost?

Surely you should be asking the distributor you are buying from the costs. Prices can vary around the world, and even locally, and discounts can often be obtained if there are future purchases or agreements to standardise.
 
We use the exact same sensors where i work (clean water treatment). Dan is right, you have only listed the pH probe. You need a transmitter to interpret the signal coming from that pH probe and give you a scaled 4-20mA output. We use yokogawa ph450 (http://www.yokogawa.com/us/ia/analytical/us-ykgw-anal-ph450-pdetail.htm). This gives a couple of 4-20mA outputs, plus relays for fault conditions, hi/lo etc

But which electrode do you use where I will measure PH of water at 95°C

I found PH20 or FU20 is good (depend on price I will use one of them)
 
At 95°C you need to be examining the spec sheets very closely for temperature limits. The pressure ratings vary dramatically at different temperatures.

You need to be scrutinizing (looking closely) at the specs.
 
You're right about pH control being non-linear. How much that influences your logic depends on the range of variation you expect, and on the alkalinity of the water. If you do a search on this site you will find several threads about pH control that may give you some guidance.

I also have trouble tuning the pH control loop in my skid.
Can you post the links to the pH PID control? I am not able to find them.

Thank you
 

Similar Topics

Hey all, Question regarding waste water treatment control standards. Without too much context, i am wondering if waste water for some reason...
Replies
5
Views
2,386
Hi all- Looking for a stand alone valve/controller to regulate wastewater flow to 100gpm. would like to make it a self contained as possible...
Replies
6
Views
5,084
D
Hello everyone, In a conversation with a major drive distributor MCCs and Kiosks were frequently mentioned and I had no clue what he meant by a...
Replies
2
Views
1,131
This system is a 1769-L32E PLC/SCADA, with three 1794-AENT flex bus remote I/O stations, over Ethernet. This system has been in place for 10 (or...
Replies
6
Views
1,936
I have a customer that needs to start logging their waster water system at the demand of the county. They need to report quarterly the daily...
Replies
16
Views
4,058
Back
Top Bottom