DO meters?

[Sauce]

Heyz,

Looking for whos using what, rough idea of price and where did you purchase.


Thanks all

JackK

[KWLSD]

Hi Jack,

We are an independent UK-based company specializing in service, repair and supply of second-user instruments for dissolved gas measurement (O2, CO2, N2). This isn't a sales pitch however..!

If you're looking for a good, robust portable meter you can use anywhere from wort oxygenation to brite tank (and, indeed, final package) I would suggest you look for an Orbisphere 3650.

These are pretty-much the commonest meter in the industry and are reliable, with good parts/consumables availability and all routine service/calibration can be carried out by the user.

There are other systems available that would be worth a look: Digox, Mettler and Mecsens being three that come to mind.

All have a track record in the brewing industry and are reliable to low O2 levels, critical for good shelf-life!

[burcher]

Any of y'all ever use a YSI DO meter? They have both replaceable membrane and twist of 'tips' with membranes. Models, from memory are about 200 for the economy version and maybe 800 for the main model. I used them extensively for water quality monitoring in a former life and have always thought they would be useful. Only drawback is they are probe based and require 'dipping' into the sample but can be sanitized like anything else. They were very accurate. I may ask to 'borrow' one from an old colleague and test it myself.

[KWLSD]

Chris,

We used to use something similar for wort O2 measurement; the difficulty for beer is that - to dip the sensor into the sample - the latter has to be open to the air, thus having an unfortunate habit of absorbing O2!

What makes this even worse is that most sensors of this type are designed to work in a flowing liquid, ie. water, so they really need the beer sample to be stirred, which means it absorbs O2 at a quite alarming rate

[burcher]

ahhhhh, yes - thanks!

[dick murton]

Had a chat with a rep from Mettler recently. His suggestion was

M200 transmitter, which is mains powered (220 - 240 / 110 - 120V) so a long extension lead may be required - approx £450

Sensor - InPro 6800 - approx £600

Flow chamber approx £50

This will give you an accuracy of +/- 6to 8 ppb, which will be plenty good enough - to the point where I almost wonder why we use such expensive kit most of the time

It is the Clark cell membrane system unfortunately, but this is a lot cheaper to buy initially than a really high accuracy instrument. I have no idea of maintenence costs

I haven't used one of these so this is not a personal recommendation. For that - Orbisphere as mentioned, or the Optical quenching instruments - but these are all considerably more expensive

And don't forget that you will need suitable sample points fitting on the plant, which then need to be cleaned / sterilised properly

[KWLSD]

It is the Clark cell membrane system unfortunately, but this is a lot cheaper to buy initially than a really high accuracy instrument. I have no idea of maintenence costs

Why 'unfortunately', Dick?

We have customers who's DO2 meters last 6-12 months between servicing, maintaining good calibration and electrode condition.

Clark Cells are a good, accurate technology and, properly serviced and maintained, are very reliable. Yes, they need to be kept clean and not abused, but that applies to any analytical kit.

Maintenance doesn't have to cost the earth either...but I'll stop there before this begins to sound like a sales pitch

[dick murton]

I tried a number of the new optical quenching sensors, and simply believe that in a year or two, the Clark cell types will not be produced any more. They are fast to respond to large changes in DO2, are not affected by pressure shocks and do not require the use of aggressive chemicals to clean, don't take hours to calibrate (< 15 minutes for some units). The cost of the new optical sensor spot is fairly expensive, but will be offset by the lack of frequent replacement of the membrane, and particularly the cost of the time involved.

Admittedly, so far there is a lack of real life long term usage, but the suppliers are learning fast as they get them out into the market

Just a shame the original cost is so high at present

[KWLSD]

They...don't take hours to calibrate (< 15 minutes for some units)..

Properly carried-out, a Clark Cell sensor doesn't take hours either

[I.D. Rinks]

How does a Orbisphere react to trub and or yeast?
How does the piercing device work for bottles or cans?

Thanks

[KWLSD]

Providing trub, yeast (or anything, really!) doesn't coat the end of the sensor then an Orbisphere will measure DO2 accurately. The same applies to any in-flow sensor, whatever the manufacturer or technology.

It isn't usual to measure in environments where there are high levels of these materials, however, for example:

Wort DO2 levels are usually measured immediately before pitching, as the yeast will be using the O2. It is more useful to know - and thus to be able to control - the O2 level available to the yeast for correct multiplication and hence fermentation.

Most of the commonly-used sensors are safe to be left in line with NaOH (caustic) cleaning; indeed this is helpful to remove any debris on the sensor face.

As to the piercer, these use a hollow 'spike' to pierce the can or crown. The spike is surrounded by a soft rubber/silicone seal to prevent pressure loss as the spike also allows gas pressure to be applied into the headspace and minimise gas breakout (to assist in accurate measurement!).

A sample tube is then lowered into the beer so that, when a flow valve is opened, the beer is forced up through the tube and to a sensor in a flow-cell.

The simplest piercers are manually controlled; some are now available that pierce pneumatically or with some form of electro/mechanical action.

By measuring DO2 or CO2 in-pack, the results can be used to ensure good packaging/filling methodology, so the beer reaches the drinker exactly as the hard-working brewer intended

[burlybeer]

Is anybody using the Milwaukee SM600 O2 meter? They are very affordable and the cost of consumables isn't high either, so of course I'm suspicious.

This is the first link that pops up on google, I'm not schilling for them:
http://www.eseasongear.com/milwaukeesm600.html

[KWLSD]

Might be okay for wort DO2 levels, but with a resolution of of 0.1ppm (ie. 100ppb) and an accuracy of +/-1.5% of full scale, which works out at +/-0.3ppm or 300ppb, it wouldn't be capable of the sort of measurements you should be looking for in brite tank or packaged beer.