Thermaworks PH meter

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I have the Thermoworks 8100, but it looks like that one is more compact with the same accuracy for half the price. I'd definitely go that route.
 
Just looking at the specs.

It has an auto calibration feature meaning the device decides after 30 seconds when to calibrate the meter. Perhaps not a major concern.

I like being able to decide when to calibrate and not rely on an automated feature.

edit: Also it is risk free if you wanted to get it and do the stability check previously linked. Thermoworks have a 1 year warranty on it and I'm guessing getting them to honor it if the device does not give stable readings would not be a problem.
 
Remember that though most manufacturers do not specify what they mean by accuracy we have more or less surmised that it is the rms value of the readings from a stability run over some period of time. As an illustration of what this means the picture below shows a hypothetical string of reading on the 4 buffer from a meter which we suppose to be specified to an accuracy of 0.05 under the assumed definition. This string of readings has an rms deviation from 4.0 of 0.047 and is thus better than the spec of 0.05 even though the errors span 0.17 pH units. While this series is in no sense intended to represent an actual sample of the product in question and any real meter's errors would be correlated over time it is nevertheless true that an instrument with a spec of 0.05 will have errors greater than ± 0.05.

Errs.jpg
 
ajdelange said:
Remember that though most manufacturers do not specify what they mean by accuracy we have more or less surmised that it is the rms value of the readings from a stability run over some period of time. As an illustration of what this means the picture below shows a hypothetical string of reading on the 4 buffer from a meter which we suppose to be specified to an accuracy of 0.05 under the assumed definition. This string of readings has an rms deviation from 4.0 of 0.047 and is thus better than the spec of 0.05 even though the errors span 0.17 pH units. While this series is in no sense intended to represent an actual sample of the product in question and any real meter's errors would be correlated over time it is nevertheless true that an instrument with a spec of 0.05 will have errors greater than ± 0.05.
Click to expand...

Am I right in thinking RMS= Root Mean Square?

Sorry if this is an obviously stupid question. Just wanted to be sure. I didn't know that's how the accuracy was categorized. Thanks for the useful plot
 
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bembel said:
and REED lists it at $99
http://www.reed-direct.com/product/...-to-14-00-ph?gclid=CITKmJe9kscCFYmPHwodON4D4w

I just ordered one, for $40 on Amazon Prime I can take on for the team as soon as Friday and return it if issues, can I purchase any 4 & 7 calibration solutions or the ones specific for this pen?
Click to expand...

Any calibration solution is fine, there shouldn't be any deviance at all. A 4 or 7 pH solution should always be 4 or 7 no matter what brand otherwise, it's not calibration fluid.
 
brew703 said:
you are lucky- Amazon just increased the price to $99.
Click to expand...

I saw that, really strange, like a teaser and then the price goes up? They changed the price shortly after I ordered, I even clicked on the "buy another" link from my $40 order history and it was back to the $99 price???

Anyone have similar experience with this? Its not bait and switch, but its not cool either
 
bembel said:
I saw that, really strange, like a teaser and then the price goes up? They changed the price shortly after I ordered, I even clicked on the "buy another" link from my $40 order history and it was back to the $99 price???

Anyone have similar experience with this? Its not bait and switch, but its not cool either
Click to expand...

Well amazon has various retailers, it'd be interesting to see if yours is fulfilled by amazon or was through another vendor selling through amazon.

I had the same thing happen though with my Bud industries Steel NEMA box for my electric panel. Its normally $70 but was on sale for $30 so i bought one and then it shot back up to $70 right after.
 
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The resolution may be 0.01 but the accuracy is 0.1 within 10 ° of cal and 0.2 within 20. I'd avoid this one as there are several alternatives that do deliver 0.01 or 0.02 for comparable money.

Distilled water is considered deionized (DI). It can be used for rinsing but not for calibration. A buffer is required for that.
 
ajdelange said:
The resolution may be 0.01 but the accuracy is 0.1 within 10 ° of cal and 0.2 within 20. I'd avoid this one as there are several alternatives that do deliver 0.01 or 0.02 for comparable money.

Distilled water is considered deionized (DI). It can be used for rinsing but not for calibration. A buffer is required for that.
Click to expand...

Once again, thank you!
I was not paying attention ( only half a cup of coffee yet)

FYI - just discovered a cool extension to track and take advantages of price drops on Amazon, so others can try to get similar deal like I did on the Reed ph meter, the company WAS dropping the price each day and I lucked out buying it at the low end, which triggered it to go back to normal price. The extension in called Camelizer from Camel Camel Camel, and it charts the historic prices too and lets you set alerts for this kind of price drop strategy that many vendors use, look that the chart for the pen, they were dropping the price every few days until someone made a purchase

In any case, AJ, I thoroughly enjoy reading ( and trying to comprehend) your extensive technical posts and responses, and procrastinated at work a good deal this week on all the articles on your website, where did /do you teach, by the way?

In the past 6 months I have self taught myself more info on bio and chem than I learned undergrad, and wonder how many more HS or college students would pay focused attention in class if all the science we put into the context of brewing :mug:

Cheers!

Screen Shot 2015-08-14 at 9.08.24 AM.png
 
bembel said:
...where did /do you teach, by the way?
Click to expand...
Mostly in my 'lab' which is a space over my garage (which contains my brewery) but I have also done classes in my living room and kitchen.

bembel said:
and wonder how many more HS or college students would pay focused attention in class if all the science we put into the context of brewing :mug:

Cheers!
Click to expand...
Oh yes. I ran into fellow that taught biochem lab at one of the local colleges and his approach was to structure the labs in a brewing context wherever possible. He said that his male students at least were enthralled!
 
ajdelange said:
Mostly in my 'lab' which is a space over my garage (which contains my brewery) but I have also done classes in my living room and kitchen.


Oh yes. I ran into fellow that taught biochem lab at one of the local colleges and his approach was to structure the labs in a brewing context wherever possible. He said that his male students at least were enthralled!
Click to expand...

OK, but you must be either bio-chem or bio-engineering by profession, right? Or is all this stuff you learned brewing in your lab :)
 
No, I was (retired now) an EE by education and experience so yes, I picked up much of the stuff I post from brewing (and reading) but a lot of it is basic science. It doesn't much matter if it's a pH electrode or an RF power meter sensor. They both have to be calibrated, they are both temperature sensitive, they are both subject to noise etc.
 
I used the Reed last night. After initial calibration it kept giving me an error that I was outside of the slope parameter and the instruction are not well written on how to adjust and operate the settings. But I remained calm instead of breaking it against the wall. Must be the new meds. In any case

Had to rely on my old $14 pen which I hastily calibrated. I was trying to get my ph for a ferulic acid rest at 5.8 and with a 1/4 of baking soda added to the mash that's what I appeared to hit. Then I added a little lactic with the rest of the next infusion to get things to 5.5. Must admit, I thought this would be easier. We will see how the beer turns out.

I called Reed early but this morning and they answered with a live human who spoke English and was very helpful at troubleshooting and getting me to reset the slope parameters. Seems to be working fine now. I had NO IDEA these pens took so long to stabilize on a value. Not seeing how this can be used practically in brewing unless it's to measure water and wort samples before. To use this while mashing seems difficult, are there other units that are less fragile or respond quicker? At this point I'm ready to spend a few more dollars.

Any tips on storing these in solution? Other than keeping the cap off and putting the pen In 50 ml flask of solution and hiding it on a shelf I'm not really sure how to do so?
 

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