Milwaukee MW-102 pH Meter Stabilty Test Results

Hey All,

Just wanted to post the results of my stability test for my new Milwaukee MW-102 pH meter. I promised I would post my findings in my original "What to buy" post, but I figured I would give this it's own thread, so others might be able to find it easier.

So how does this data look? (Looks REALLY good to me, I think?)

Anyway here are my results:


Pretty Graph:


Not sure if it's better looking at this info as a Scatter Graph to be more representative of the time x-axis:

Not sure if this is good or not but can you explain the procedure? Are you just measuring the 4.01 buffer soln over time? Is it a fresh pour of buffer each measurement or same pour? If same pour how are you handling between pours?

eric19312 said:

Not sure if this is good or not but can you explain the procedure? Are you just measuring the 4.01 buffer soln over time? Is it a fresh pour of buffer each measurement or same pour? If same pour how are you handling between pours?

Click to expand...

I tried to follow what AJ outlined in the pH Meter calibration sticky.

Procedure:

• I am just measuring the 4.01 buffer over time
• I used same buffer pour over and over again during the course of the test.
• The test buffer was stored in a small sealed container between tests.
• Before each test, I remove probe from storage solution, rinse with DI water then wipe probe with towel to remove excess water. (Blow out bulb area a little where water gets trapped)
• Put probe in buffer along with temp probe, swirl both for a few seconds.
• Wait for meter to come to stable reading (About 30 seconds)
• Note pH and Temp from meter.
• Remove both probes and rinse in DI water.
• Dry probes once again
• Return pH probe to storage solution

Looks good to me. The bias suggests that if you wait a little longer before accepting the cal values you might do even better but this is certainly good enough.

Just for grins, I was curious how my new meter was holding calibration since the last calibration.

Last time I calibrated was for the original post back on Aug 28, 2014. So I took my meter out and read that same calibration solution that I had in a sealed container and read it at a pH of 3.96.

That is about 10 days post calibration!! and as AJ pointed out, in my original calibration, I definitely didn't wait long enough to accept the calibration. I rushed it and should have waited longer for it to stabilize for a better calibration.

Still VERY happy that after 10 days I am still darn close!

CyclingCraig said:

Just for grins, I was curious how my new meter was holding calibration since the last calibration.

Last time I calibrated was for the original post back on Aug 28, 2014. So I took my meter out and read that same calibration solution that I had in a sealed container and read it at a pH of 3.96.

That is about 10 days post calibration!! and as AJ pointed out, in my original calibration, I definitely didn't wait long enough to accept the calibration. I rushed it and should have waited longer for it to stabilize for a better calibration.

Still VERY happy that after 10 days I am still darn close!

Click to expand...

Just make sure that you clean that thing well and get the cleaning solution; my MW-102 started taking longer, and longer (4ish minutes) to get a stable reading over time despite being rinsed well and properly stored with Hanna storage solution; properly cleaning it enabled it to work faster.

Personally, I find the separate temp and ph probes a bit annoying and the whole thing a bit slow, but I don't know any ph meter that's faster at this price and accuracy, so nit picking, really. The temp and ph features integrated into a single probe with a "high speed mode" for the next version, would certainly be welcomed, anyway.


Adam

In brewing protein is going to build up on it eventually. This can be removed with an enzyme based cleaner such as Zymit or a similar product.

You can buy electrodes with the temperature sensor built in and a separate cable with the 2.5 mm connector. I'm assuming the temp sensor used by these meters is a 100 Ω RTD.

ajdelange said:

In brewing protein is going to build up on it eventually.

Click to expand...

Yep, I thought I was ok just rinsing it, and I couldn't SEE anything on it, but the difference in performance before and after cleaning it was HUGE.

I wonder how many complaints about the stability waning over time are related to protein crusted probes...

ajdelange said:

You can buy electrodes with the temperature sensor built in and a separate cable with the 2.5 mm connector. I'm assuming the temp sensor used by these meters is a 100 Ω RTD.

Click to expand...

Wow! Thanks for the tip; now I know what to buy when the current one finally wears out. -You really ARE like consumer reports for pH probes! ;-)
*Now the # of PMs you get asking you for pH probe purchasing advice should triple*. ;-)



Adam

The temp meter on mine seems to be the most accurate of the ones I own. I'd hate to lose the use of it at higher temps.

ajdelange said:

In brewing protein is going to build up on it eventually. This can be removed with an enzyme based cleaner such as Zymit or a similar product.

You can buy electrodes with the temperature sensor built in and a separate cable with the 2.5 mm connector. I'm assuming the temp sensor used by these meters is a 100 Ω RTD.

Click to expand...

Would denture soak like Polident an over-the-counter available in every grocery or pharmacy also work to clean protein off of probes?

How often should the probe be cleaned with an enzymatic cleaner?


Sent from my iPad using Home Brew

I don't know how much polident is but I use:
Milwaukee Instruments Storage Solution for pH/ORP Electrodes

EDIT: Posted the wrong thing. Home brew WAS involved:
http://www.ebay.com/itm/Milwaukee-M...142?pt=LH_DefaultDomain_0&hash=item3f2f6af826

Milwaukee even suggests using vinegar to clean the probe:
http://www.milwaukeeinstruments.com/pdf/pH_Application_Info.pdf

youngdh said:

Would denture soak like Polident an over-the-counter available in every grocery or pharmacy also work to clean protein off of probes?

Click to expand...

There are certainly lots of enzyme based cleaners out there but I don't know if Polident is one. I always use Zymit for jobs like this as it is now possible to buy one liter (which should last a long time since it is used in 1% v/v solution) for a reasonable, but steep, price. I think Martin found a product that works and posted about it a while back.

youngdh said:

How often should the probe be cleaned with an enzymatic cleaner?

Click to expand...

As often as it needs it. Thinking back over it I haven't cleaned a pH electrode since I can remember but a good indication that you should try cleaning is the slowing response that people have mentioned here. The manufacturer of your electrode should have furnished 'rejuvenation' instructions which may include things like soaks in HCl and NaOH. Be sure to do those too but as protein is a thing we have to deal with in beer I'd go for the proteolytic enzyme cleaners first.

Also note that we are talking here about a cleaning solution which is distinct from a storage solution. They do different things.

Well I wish I had found a cheap enzymatic cleaner for probe cleaning, but all I did was suggest that some of those grocery store cleaners such as an enzymatic carpet spray MIGHT be suited. I still haven't tried it yet. I am pretty sure that there are some carpet or laundry stain remover sprays that say they are suited for protein stains. I am guessing that they may have proteolytic enzymes.

Posted the wrong thing. Home brew WAS involved:
http://www.ebay.com/itm/Milwaukee-MA9015-pH-ORP-Electrode-Probe-Storage-Solution-230ml-hanna-hi70300m-/271378479142?pt=LH_DefaultDomain_0&hash=item3f2f6a f826

Milwaukee even suggests using vinegar to clean the probe:
http://www.milwaukeeinstruments.com/pdf/pH_Application_Info.pdf

Slightly off topic but I was wondering what causes mold to grow in probe storage bottles...does the solution become contaminated?

Hermit said:

Posted the wrong thing. Home brew WAS involved:
http://www.ebay.com/itm/Milwaukee-MA9015-pH-ORP-Electrode-Probe-Storage-Solution-230ml-hanna-hi70300m-/271378479142?pt=LH_DefaultDomain_0&hash=item3f2f6a f826

Milwaukee even suggests using vinegar to clean the probe:
http://www.milwaukeeinstruments.com/pdf/pH_Application_Info.pdf

Click to expand...

Vinegar will only help soften calcified deposits and not protein based deposits.


Sent from my iPad using Home Brew

Searching online for Zymit the only place I'm finding it is from the US supplier direct at www.ipcol.com. Unfortunately you have to purchase by the case and it's expensive plus it has a limited shelf life.

I did a general search for enzymatic cleaners and stumbled on this DIY citrus cleaner on wikihow.com http://m.wikihow.com/Make-Enzyme-Cleaner. The initial instructions end with "wait 3 months then..." but they have a part 2 at the end that by adding yeast, which us homebrewers don't lack, you can reduce the fermentation process down to 2-3 weeks.

This does raise the question if any citrus cleaner could be used to rejuvenate sluggish pH probes or if any pet stain remover could be used as a soak that states removal of pet urine, feces or vomit?


Sent from my iPad using Home Brew

You can get it from Cole-Parmer by the liter but it is over $30. OTOH the case price brings it down to about $14/L. It would make, thus, a good 'club buy' proposition. Shelf life is finite but, IIRC, pretty good. I used the free sample Cole-Parmer sent me with some purchase for several years and am now on the first liter I actually bought (they only sold by the case for quite a while) a couple of years back.

I have a follow up question with regard to the calibration buffers.

I purchased the buffer pillow packs from Hach:
4.01 Pillows

Can I mix them up the night before my brew day and store in a sealed container, so they will be ready for me the next day when I calibrate the meter? Will they still be "Good"?

I like to get as much done the night before my brew day to make the day easier.

I plan to weight the DI water out on a accurate scale to get the 50ml , I would like to be as precise as possible to mix the powders. Is that a reasonable way to measure the water? (Density of the DI @ room temp used to calculate the weight)

Thanks again
-Craig

Yes, they are absolutely good overnight. In fact, in a sealed container, they are good for weeks.

Yes, that is a very reasonable way to measure the water. Keep in mind that the density of DI water at room temperature is 0.998203 gram/cc. Also keep in mind that you are dealing with a buffer which will try to hold pH irrespective of small error in the amount of water. In a pH 7.00 phosphate buffer adding an extra 5% water would shift the pH of the buffer by about 0.02 pH.

My main computer won't boot so I don't have a date but I brewed about 1 month ago. My readings today when I tested the probe are 7.00 and 3.98. I don't think I'll bother running the calibration routine.

Edit: Just to be clear I have the MW102 which is why I posted in this thread.

ajdelange said:

In brewing protein is going to build up on it eventually. This can be removed with an enzyme based cleaner such as Zymit or a similar product.

You can buy electrodes with the temperature sensor built in and a separate cable with the 2.5 mm connector. I'm assuming the temp sensor used by these meters is a 100 Ω RTD.

Click to expand...

I bought some Milwaukee MA9016 cleaning solution. Do I just soak the probe in the solution or scrub it with something like a toothbrush?

Or it may just be time to buy a new probe as mine is almost 3 years old.