View Full Version : TDS meter calibration at the meeting
05/18/2006, 07:44 AM
Hey guys, so I wanted to talk about the standards for our TDS meter calibration.
I can make them up but I was wondering about something. It says to calibrate them with NaCl, leading me to believe I should make up some solutions of say...1, 5, 10 ppm NaCl.
Is this what you guys want me to do?
1ppm, 5ppm, and 10ppm solutions? I don't see the point in going a whole TON higher. Maybe 5, 10, 20 would be better?
Let me know and I will make these up for us!
05/18/2006, 08:43 AM
1ppm, 5ppm, and 10ppm would be ideal, I think. That is the area of the curve we are wanting to see, anyway. Nothing wrong with a slightly higher setup, but I'd before to see it down low since I regularly get readings of 4ppm to 9ppm on my present setup.
05/18/2006, 11:21 AM
I think most calibration solutions are pretty high like the ~300-800ppm range. My meter recommends 342ppm. I'm just wondering if there would be any difference if we used 5/10ppm vs. something higher.
05/18/2006, 11:39 AM
Well the reason we wanted to use really low standards is because the values we are measuring are so low.
It will not read accurate at all down in the <10 ppm range if you calibrate it at 300ppm. So we are going to calibrate them low in the hopes that they will read better in the lower range, ya know?
05/18/2006, 01:03 PM
Yep, agreed. :rollface:
05/18/2006, 05:29 PM
Could we calibrate low and then check against a high concentration to see how much accuracy is lost due to calibrating at different levels? Just a thought.
05/19/2006, 02:47 PM
Hi guys, ok so here's what I did:
The 1 ppm standard seems to be below the detection limit of the meter so that standard didn't work. I could never get it to read the 1 ppm solution no matter how far I cranked the screw on the back.
So I made five each of 5, 10, 20 ppm solutions for some people to take home and a single 100 ppm solution for us to mess around with at the meeting. I figure that not everyone needs the calibration solutions so we can just share the five amongst ourselves. For example, Art and I live 5 minutes apart so we don't need two sets of solutions so we will share one set. People who live close together can just share. If I need to make more solutions because someone desperately wants another set, then I can easily do that because I kept my stock solution and would only have to redo some dilutions.
OK? Everybody happy?
05/19/2006, 03:29 PM
Thanks Mel. I have an unopened 800 ppm that came with my in-line tds. I'll bring it along if anyone wants to mess around with it and the 100 youre bringing. My thought is that it would be better to calibrate a 10 & 100 than a 100 & 800 but I happen to have this pouch sitting on my desk and I may as well let "someone" use it if they want to - I have no use for it as long as our helpful mad scientist is around.
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