What's Been The Most Inaccurate Equipment You Have Bought?

[np1962]

my wife h34r:

a hydrometer.,

edit: oops nigeP62 beat me too it

Mine has been away nearly 3 weeks, but, damn it, she has taught her 16yo daughter to be just like her!!!

 

[chappo1970]

I'm probably the most inaccurate piece of equipment in my brewery... h34r:

Definitely Thermometers has been the bane of my existance been through a heap of 'em but now have 2 glass ones that are my measure for all things including the Dial thermometer. I sooo hope I won't break one or I'm stuffed.

Cheers

Chappo

 

[EK]

Stick on thermometers, though I use them on all my fermenters.

Plastic kitchen scales. The box should have read: "Every reading unique!"

:icon_cheers:
EK

 

[braufrau]

The bathroom scales .. wrong as wrong can be!

 

[peas_and_corn]

The bathroom scales .. wrong as wrong can be!

So I'm not really a fat load?

 

[Fourstar]

Be weary of using Sight (laser) thermo's during your mash, mine was 10deg out because of steam temp. perfect to use when measuring your ferment temp or keg temp however.

best investment was a .1+- resolution digital probe thermometer from ebay for a mere 12$. Same product in the local home wares store is $45. Bargain and is accurate too!

 

[jjeffrey]

My refractometer. I don't think it ever read the same number twice. Except 0 with water.

Same same.

Not too long ago, I bought a refractometer. The first brew I did I thought I had a stuck lager fermentation (wouldn't drop below 4.5 Brix), until I measured with my hydrometers- they reported 1.009. That prompted me to do a calibration with sucrose at 20degrees, using my lab gear for temperature, mass and volume measurement. What I found was that the refractometer and my 3 hydrometers all agreed very closely and were accurate when compared to a range of standard sucrose solutions. Refractometer was plus or minus 0.2 Brix, and hydrometers plus or minus 1 point. However, used to measure wort and beer, it was a different story. With unfermented wort all instruments were within cooee (2 points difference max), but as fermentation progressed, the refractormeter would diverge from the hydrometers. The heavier the beer (that is, the greater the ratio of unfermentables to fermentables), the greater the divergence. At the end of my oatmeal stout fermentation, for example, the refractometer reported 7.5Brix (1.030), where as my hydrometers told me 1.016. I recorded data from 3 batches which all exibited the same behaviour, but to varying degrees depending on the type of beer.

Turns out, that maltose has a refractive index which is pretty close to sucrose, but more complex dextrins have a greater refractive index (increasing with complexity). This means that at the start of fermentation the refractometer error is not great, but as you use up your maltose, the error increases.

I've gone back to the hydrometers.

jj

 

[np1962]

Same same.

Not too long ago, I bought a refractometer. The first brew I did I thought I had a stuck lager fermentation (wouldn't drop below 4.5 Brix), until I measured with my hydrometers- they reported 1.009. That prompted me to do a calibration with sucrose at 20degrees, using my lab gear for temperature, mass and volume measurement. What I found was that the refractometer and my 3 hydrometers all agreed very closely and were accurate when compared to a range of standard sucrose solutions. Refractometer was plus or minus 0.2 Brix, and hydrometers plus or minus 1 point. However, used to measure wort and beer, it was a different story. With unfermented wort all instruments were within cooee (2 points difference max), but as fermentation progressed, the refractormeter would diverge from the hydrometers. The heavier the beer (that is, the greater the ratio of unfermentables to fermentables), the greater the divergence. At the end of my oatmeal stout fermentation, for example, the refractometer reported 7.5Brix (1.030), where as my hydrometers told me 1.016. I recorded data from 3 batches which all exibited the same behaviour, but to varying degrees depending on the type of beer.

Turns out, that maltose has a refractive index which is pretty close to sucrose, but more complex dextrins have a greater refractive index (increasing with complexity). This means that at the start of fermentation the refractometer error is not great, but as you use up your maltose, the error increases.

I've gone back to the hydrometers.

jj

Someone smarter than me will come along and give you the formula for adjusting refrac reading of fermenting wort.

Nige

 

[peas_and_corn]

For your FG, you need to run the number through a calculator since alcohol also refracts light- you did this, right?

 

[barry2]

How accurate is whatever we are calibrating with?
Some months ago I carried out a "water audit" to check on daily water consumption.As part of that I measured out 10 litres of water from a tap using a supermarket 2 litre jug. The water meter registered 9.8 litres.I would like to think that I am paying for less water than I use but suspect both readings are wrong.

 

[jayse]

:icon_offtopic: spare a thought!
Inaccuracy of cheap homebrewing equipment is nothing if you compare it too all the poor *******s that invested in scud missiles, woefully inaccurate and you can't just go down the road to the shopping centre and get new ones at a cheap price. :unsure: also they sure had a lot more too loose than just 20 litres of slightly different beer than expected. :lol:

 

[Mantis]

Do the refractometers come with instructions. I just ordered one a couple of days ago

 

[jjeffrey]

Someone smarter than me will come along and give you the formula for adjusting refrac reading of fermenting wort.

Nige

That'd be nice.

 

[jjeffrey]

For your FG, you need to run the number through a calculator since alcohol also refracts light- you did this, right?

nope. I did start mucking around with the various tools on beersmith, but eventually I cracked the ***** and packed it into the cupboard. Really, what I need to do is spend a bit more time finding out how to use the thing properly, I suppose.

 

[flattop]

Me being casual

 

[jayse]

nope. I did start mucking around with the various tools on beersmith, but eventually I cracked the ***** and packed it into the cupboard. Really, what I need to do is spend a bit more time finding out how to use the thing properly, I suppose.

Its pretty easy go down the bottom of the beersmith sidebar and hit refract tool, select fermenting wort gravity, type in the brix reading and whatever the starting gravity was and you have it.

 

[pdilley]

Light and Dark worts will comprise of different mixes of fermentables and non fermentables so there is no one universal correction. That said, prefermentation Brix to Plato is 1.04. 1.02 to 1.06 are the normal correction ranges with worts depending on the recipe. If all you ferment is wort exclusively then you have to train your refractometer against a trusted hydro for a brew to determine the most exact correction value for that recipe then you can rely on the refractometer for future brews of that recipe.

Once you gain alcohol during fermentation, it also refracts light differently to sucrose in solution. However its refractive influence at evet increasing levels is well known and predictable at good precision in a single formula so once you have the OG reading, any future Brix readings use the original Brix reading in the formula and you track Alc content exactly.

Because you work on the physics of bending visible spectrum light it behaves differently to displacing a weight in liquid solution. So they do not behave the same. If you start with hydro and switch to refractometer youll swear its not working right. If you start with refractometer and switch to hydro you'll raise an eyrbrow on your first few brews worth of readings. Hydro is linear, it drops from one reading down close to 1.0 or just below. Refractometer is not linear but a curve, as alc increases the numbers decrease towards 1 at a slower and slower rate.

A straight Brix reading to Plato conversion because we are dealing with wort with mix of sugars instead of all sucrose in water would be:

Brix of 5.25
Plato = 5.4
Plato to Specific Gravity = 1.021

Now this fine if you use this as OG and then pitch in yeast and begin yhe fermentation.

This is *NOT* fine if you pitched yeast 4 days ago and it has been fermenting into alcohol.
You have to go get your original Brix or SG value and plug it into the original alcohol correction formula with your current Brix reading you are getting, 5.25 in this case. The OG value will determinr the Specific Gravity of the current refractometer reading. If it was high maybe your corrected SG will be 0.991 instead of the straight 1.021 conversion. If you started low then 5.25 Brix might correct to 1.012 instead of the straight conversion value of 1.021.

This imho is the source of all th deviation head scratching sessions new refractometer users are getting and beer brewers have one more head scratching to do than wine or mead brewers.

Wines and Meads, take an original Brix reading and write it down. If you need SG number just skip the conversion to plato formula and just treat it as plato in the plato to specific gravity formula. All future readings after yeast just apply the alc correction formula.

Beers, each style needs a calibration for Plato conversion from Brix. Use 1.04 if you want to guess and dont care about being accurate. Write down as OG. All future readings need to run through alc correction formula using the OG and current reading.

Excel spreadsheets and web pages exist that do this all for you but you have to know about the whys above to use them fully and accurately.

Its a slight extra work step for some to gain the 2mL or less per reading step performed compared to ~300mL romoved per reading for hydrometer. Others might call it a mountain, others again a mole hill. If you are brewing 60 liters then 0.3 litres lost per reading is not an issue. If you brew small batch 5 litre carboy batches then two hydro readings means you lost a wine bottle when you are only gettng 4 to 5 bottles in the whole batch you may now only get 3 or 4 bottles.

Degass your samples either tool you use. Omitting temp correction formulas step with hydrometer readings as most will know that already. Refractometers also have temperature corrections if you dont have an ATC model which isnt a cure all if you measure liquids falling to the extreme ends of the ATC range which is usually +/- some number C or F listed in your refractometer manual. Know that colder skews less than hotter temps so I would worry more about accuracy at 30 C than at 10 C.

 

[pdilley]

My equipment of dubious accuracy are all mentioned:

Plastic Kitchen scales of dubious readings
-- Ive jiggled them more than SWMBOs tits in an many an attempt at good readings
-- Ive now replaced with 0.1g resolution and 1g resolution digital scales

Thermometers:
-- Ive asked for laboratory grade glass thermometers and gotten strange stares by people over here
-- I brought a lab grade glass thermometer in from a trip to the States and it broke in luggage handlers hands no matter how well packed. Next time im bringing it in on my body

LHBS kits included instructions, need I say more
-- been swictching to AG recently
-- all meads, ciders, wines are done with real ingredients, not expensive Goo Tins with dodgy yeast and super dodgy instructions

 

[jlm]

-- I brought a lab grade glass thermometer in from a trip to the States and it broke in luggage handlers hands no matter how well packed. Next time im bringing it in on my body

Um, internally....I'm going to invest in one of those self calibrating digital jobs someone posted in another thread recently. I've found its not hard to knock a dial thermo out of whack when cleaning the mash tun, anything that can bump it around a bit. Glass things (Thermos and hydros) and me have a bad relationship though, some drunk ******* keeps breaking them.

 

[t2000kw]

Turns out, that maltose has a refractive index which is pretty close to sucrose, but more complex dextrins have a greater refractive index (increasing with complexity). This means that at the start of fermentation the refractometer error is not great, but as you use up your maltose, the error increases.

I've gone back to the hydrometers.

jj

Thanks for that experience! I'll buy a narrow range hydrometer first to make it easier to read for my aging eyes. Then I'll consider a refractometer and figure out how to use the tool in Pro Mash to correct the readings.

Somewhere I seem to remember reading that you can calculate OG from just an FG reading using a refractometer. Anyone remember reading that, and if so, does it work?

Donald