SO2 Analysis

Cellar Rats (ITB)
21

I don’t have the Hanna for SO2, but I do use their TA titrator machine. One tip a friend of mine gave me was to plug it into a surge protector (I have mine plugged into the power back-up my computer is plugged in to) as power surges or any power variability can really affect the machine. We are very prone to power surges where we are. Do you ever experience problems like that? It might be something to look into.
I too had looked into making my own solutions, but I think they are secretive so that they can sell their overpriced stuff. For ithe TA machine you use an 8.2 pH buffer to standardize your pH electrode- even that is not readily available through scientific supply catalogs. The other solutions- I could probably figure out how to make the titrator solution, but I haven’t had a chance to try to figure it out yet.

22

We’ve used the Hanna for about 2 years now and it’s proven to be economical (<$2 per) and reliable. We calibrate about every 20 barrels per day just to be safe, though I will admit that there has been little valid variation on random retests of “round 1” calibration samples. When we first bought it, we ran lots of head-to-heads against AO and our local commercial lab. I’ll have to go back and look at the data, but as I recall all methods were within 2-3ppm. Which one was “right” is another question entirely… :slight_smile:

23

Michael:

I’m curious at to why you run 3 tests per year per batch (barrel?).
Also, when you figure $12.- per batch, do you include the operator time?
Thanks
E

24

Good tip about the surge protector. I haden’t thought about that, but our power is always going out/off and on. I have lost so many electronic devices over the years, It would be horrific to lose a $8k titrator to a simple power surge.

We only make around 1500 cases a year, but all lots are picked and fermented a ton/1.5 at a time, so we have 30+ small lots to keep an eye on. The Hanna seems perfect for this situation and I can’t wait to finish the lab station and get titrating- wow that sounds super geeky! [shock.gif]

Thanks for all of the advise guys, and Linda! [wink.gif]

25

Hey Emilio,

We don’t yet have the luxury of counting operator time into the mix…There are two of us and we are pumping our revenue right back into production. Soon, though!

Also, we run 3 batches of test per year- one after MA, one about 3 months later, and a final batch of tests just before bottling. Our current production fits into 3-4 tanks, so we don’t have to do individual barrel testsing, unless we get antsy. We typically just wait to test until after we have blended barrels.

26

All the info here helps, everyone. I have heard from a few other places about the range in results from the hanna 84100, but I guess it comes with the territory. The alternative for me would have been the oxidation/aeration setup, which has a better result record, but much more room for operator error. And as mentioned, we are growing…so the expenses of these tests will eventually decline (a couple bucks sounds great!). The surge protector is also a great idea, Linda. Here in Woodinville we get some crazy wind and seem to lose power every winter.

On another note, I received a box from Hanna with a new bottle of standard (500ml instead of the 200ml bottle the machine comes with) and a new pump tube to try to fix our “error” messages. Hopefully this works and I can actually test some wine! Pretty cool of them to give us the extra standard to make good on us needing to run through the whole bottle the first time.

27

Michael:

Just saw this follow-up. We have a 901W. There was no mention in training or on the product list of calibration for the potentiometer. So, no, we do not calibrate that side. We do calibrate the pH probe often.

In my experience, Hanna’s customer service is top-notch, so not surprising to hear they are helping you out.

3 tests 3 times a year, huh? I probably would have stuck wit a contract lab. Ours is running just about every day doing something or other.

28

They have been really great- actually waiting for a call back now. We are still not able to calibrate the machine…the latest probe that was sent appears to be broken.
I was really close to sticking with the lab or getting the airation/oxidation set from R&D glass, but here the free and total so2 tests go for $15 a pop, so I felt the money could be used well as an investment toward the machine. Next year we’ll up the ante and add a few more tanks, then the following year we’ll do the same… I’m hoping to quit my day job in the next 5 or so years!

I wish I could put a 901 in my collection! It’s really interesting that it doesn’t need a pump calibration. Wish mine didn’t either- if that were the case maybe we would have completed a test by now!

29

I’ve got the Hanna machine, and it seems to me that when I retest the same sample when it sits for a couple hours between tests, the variation hasn’t been random. I think the free SO2 has consistently dropped on the later test, and I chalked this up to normal bind up with oxygen exposure rather than to inconsistency of the machine. The take home lesson for me was that sending samples out to a lab (where the time factor makes free SO2 drop inevitable) isn’t a viable substitute for the ability to do your own analysis immediately after drawing a sample.
Have other people found variation in retests to really be random?

30

We just received our 3rd probe and 3rd set of chemicals from Hanna and the machine will still not complete a pump calibration. It has been 1 month since the beginning of our attempts and we have received replacement components every week since then. The probes have consistently provided incorrect readings from the standards when the machine has been started in a test mode. I am guessing the machine is broken, rather than ALL of the other components they have replaced. How frustrating. I needed this thing to work like last month! [soap.gif]

On a side note, though…Their product support department is still pretty awesome. They have been super willing to send the components without hesitation. Thanks Rob.

31

I couldn’t get mine to calibrate last week and spoke with customer support. The guy I talked to (Kearny I think) said that besides the bad probe possibility, the dosing tube is another likely point for the machine to fail. When I took mine off of the pump/rollers on the back of the machine, it was definitely flattened out. Evidently, they also stretch and throw off the calibration. The support guy’s advice was to always remove the tube from the rollers when you are done. I guess I’ll do so, since the replacement tube is (like everything else associated with the Hanna machine) way overpriced for what it is.

32

Addendum to the previous note about removing the tube from the rollers – when you do so, the solution is apt to siphon out if you just leave the tip in the holder. I lost half a bottle of the stuff that way. The tip needs to be elevated when the tube is off the rollers…

33

Those are both great tips- It makes perfect sense that the tube would flatten. We now have an extra tube (from all our trouble shooting), which is nice…but Hanna has my machine now and I won’t be getting a replacement until the backorder has cleared…

Our customer service rep suggested flushing the tube if it will sit for a prolonged period of time unused (weeks or longer)…so for us, we use it for one or two days staraight, then we will be clearing the tube with distilled water and then draining it completely.

34

so it sounds like your machines are peristaltic pumps and what you may be calibrating is the delivery of the pump?

that’s why we don’t need to calibrate (or at least weren’t led to believe that we did). The 901 delivery system is a piston pump.

FWIW I take my peristaltic must pump rollers out in the off-season for the same reason.

35

The piston pump must be really accurate! It doesn’t need to calibrate because it always delivers the exact same measurement of whatever size the piston cavity is- right?

I finally heard back from Hanna. They have been testing my machine for the past few days and have had the same unusual trouble with it. A chemical engineer performed the calibration with incomplete results 3 times and got a wine sample to read 400 ppm. They even got the president of the company in to have a look at the odd problem. Now, after owning this thing for 4 months, I should have one that works sometime next week.