How can I tell if the refractometer is ATC? Do I believe the seller?

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peripatetic

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Hello,

I bought a refractometer on eBay, and in the description it said ATC (Automatic Temperature Correction or something like that). There is no indication on the case or the refractometer or the directions that this item does in fact have ATC. I asked the seller, and this is what he said:

How do you know the refractometer has ATC? EASY! The unit has a bimetallic ATC that
will vibrate when the unit is lightly struck.

Here's how you can tell...(no other Seller on eBay will even know!):

1) grasp the RHB-32ATC by the daylight plate and prism.
2) gently, but firmly tap the eyepiece end in the palm of your free hand.
3). Did you feel the vibration? That's the ATC bimetallic strip vibrating.

The manufacturer didn't put the sticker on the outside of the box.
Click to expand...

Is that true? I can feel something in there vibrating when I tap it against my hand, but for all I know _all_ refractometers do that.
 
Test at room temp, test at fridge temp ? Start a new thread, become a hero and get a thousand posts in less than a month. :D

Or just take the seller word.

-OCD
 
True, the sample will quickly reach the same temperature as the refractometer, but the refractometer still has to be corrected for ambient temperature.
 
Most of the commonly available cheap Chinese made refractometers sold these days have the ATC feature. I've yet to see one that does not. I'm sure there are some older models around that don't have it though, otherwise they wouldn't bother to tout the feature on the newer ones.

The ATC feature compensates for the temperature of the instrument, not the sample. The instrument has no means to detect the sample temperature.
 
Yuri_Rage said:
True, the sample will quickly reach the same temperature as the refractometer, but the refractometer still has to be corrected for ambient temperature.
Click to expand...

Catt22 said:
The ATC feature compensates for the temperature of the instrument, not the sample. The instrument has no means to detect the sample temperature.
Click to expand...

exactly - good points. The ATC refers mostly to the temp of the instrument it self - don't leave it in the sun or the freezer....
 
It is the ambient temperature that is variable in my case, since I brew outside. Winter = cold, summer = hot.

However, I brewed today (yay!) and calibrated the refractometer. That process took about 3 minutes. So, I suppose that with or without ATC, I'll just go ahead and re-calibrate every time. I brew with distilled water, so I have it around to use as calibration juice.

Thanks for all the info!

beerocd said:
Start a new thread, become a hero and get a thousand posts in less than a month. :D

-OCD
Click to expand...

Hey! You saw right through me! ;)
 
You shouldn't need to calbrate it often and tap water works just as well as distilled. Unless, of course, your tap water is really mucky for some reason. Mine holds it's calibration very well.
 
Brewer3401 said:
I think you calibrate it to zero using distilled water.

Read the instructions - if you don't have, Google it.
Click to expand...

Try this. Calibrate it with distilled water then check a sample of your tap water. I doubt you will be able to discern a difference for two reasons. These instruments are not that precise and there isn't much, if anything, in tap water that would influence the reading. Yes, sure the instructions will tell you to use distilled water. That's the safest recommendation for them. What alternative would they have? Maybe a lab certified calibration solution, but that would not be very practical IMO. I cannot detect a difference between tap water and distilled SG even using my good hydrometer and they are more precise than the refractometers although they operate on a different principle.
 
Brewer3401 said:
I think you calibrate it to zero using distilled water.

Read the instructions - if you don't have, Google it.
Click to expand...

This will zero it out... but then you have to determine the correction factor. Mine is 1.054 If you do not do this, you will not get accurate readings.

What is yours?
 
peripatetic said:
It is the ambient temperature that is variable in my case, since I brew outside. Winter = cold, summer = hot.

However, I brewed today (yay!) and calibrated the refractometer. That process took about 3 minutes. So, I suppose that with or without ATC, I'll just go ahead and re-calibrate every time. I brew with distilled water, so I have it around to use as calibration juice.

Thanks for all the info!



Hey! You saw right through me! ;)
Click to expand...

Did you already determine the Brix correction factor? What did it come out to be?

Calibrating it to "0" with distilled is one thing, but your readings will be inaccurate unless you determine the Brix correction factor so that you can get Plato.
 
What's a correction factor?

My refractometer read 17 brix. according to this site that translated to 1.068. My hydrometer read 1.070 - 1.072. So, close. For my purposes, probably close enough. Also, that hydro reading was with slightly warm water, so I correct down for that, right? That would make it even closer.
 
Catt22 said:
Try this. Calibrate it with distilled water then check a sample of your tap water. I doubt you will be able to discern a difference for two reasons. These instruments are not that precise and there isn't much, if anything, in tap water that would influence the reading. Yes, sure the instructions will tell you to use distilled water. That's the safest recommendation for them. What alternative would they have? Maybe a lab certified calibration solution, but that would not be very practical IMO. I cannot detect a difference between tap water and distilled SG even using my good hydrometer and they are more precise than the refractometers although they operate on a different principle.
Click to expand...

I agree - unless you're the head brewer at Bud, it won't make a whole lot of difference.

I have a small bottle of RO (reverse osmosis) water I got from my office. That's what I use to calibrate.

OG-FG is somewhat important, especially if you are "way off" on either.

Focus on sanitation - that may be the most important brewing variable.

Have fun, and brew well...........and like what you brew.
 
peripatetic said:
What's a correction factor?

My refractometer read 17 brix. according to this site that translated to 1.068. My hydrometer read 1.070 - 1.072. So, close. For my purposes, probably close enough. Also, that hydro reading was with slightly warm water, so I correct down for that, right? That would make it even closer.
Click to expand...

The correction factor is what you have to mulitply Brix by to get Plato which is then where your gravity comes from. Wort contains other solids and therefore there is a correction factor that each brewer should be using, specific to thier system to achieve correct readings.

A difference of 4 points is a fair amount IMHO

Using that above info, your correction factor would be 1.030 to 1.058 or so...
 
The Pol said:
The correction factor is what you have to mulitply Brix by to get Plato which is then where your gravity comes from. Wort contains other solids and therefore there is a correction factor that each brewer should be using, specific to thier system to achieve correct readings.

A difference of 4 points is a fair amount IMHO

Using that above info, your correction factor would be 1.030 to 1.058 or so...
Click to expand...


Another thought (a very simpleton one) is to take your extremely small sample indoors - wait 2-3 minutes to get to ambient temp - then check it.

No correction needed.

Also, if you have a lot of junk in your sample, strain it through a piece of paper towel folded twice to filter it - no more junk.
 
No, that's not a simpleton thought. It is a very reasonable thought -- "if it is super cold outside, take your reading inside, genius."

Yeah, I've been brewing today. I always drink when I brew.
 
The Pol said:
Did you already determine the Brix correction factor? What did it come out to be?

Calibrating it to "0" with distilled is one thing, but your readings will be inaccurate unless you determine the Brix correction factor so that you can get Plato.
Click to expand...

but can't you go straight from Brix to gravity by:

Brix/1.04*4

?
 
AZ_IPA said:
but can't you go straight from Brix to gravity by:

Brix/1.04*4

?
Click to expand...

I think it's brix x 4 x 1.04. The 1.04 factor is typically used as a default factor in lieu of an actual calculated brewhouse factor unique to a specific brewery. I use this default value myself as I don't see a need to be any more precise than that with a refractometer. I then take a hydrometer sample to establish the OG post boil with more precision.
 
AZ_IPA said:
but can't you go straight from Brix to gravity by:

Brix/1.04*4

?
Click to expand...

What Catt22 said... you are basically using an average 1.040 correction factor. The number is actually different for each system.

So, no you cannot go direct from Brix to SG by using that formula. Yes it is an approximation.
 
The adjustment factor is because the refractometer reads the concentration of sugar in water via its index of refraction.

Wort is not simply sugar in water, ergo you get an index of refraction that implies an incorrect sugar concentration.

The correction factor would vary from brew to brew, you have to live with an average.
 
Learned yet another thing on HBT. You need a measuring instrument to correct your measuring instrument. Over how many brews do you average? Or do you find an average per type of brew. Like Hefe vs. Pils would have diff correction factors?

-OCD
 
beerocd said:
Learned yet another thing on HBT. You need a measuring instrument to correct your measuring instrument. Over how many brews do you average? Or do you find an average per type of brew. Like Hefe vs. Pils would have diff correction factors?

-OCD
Click to expand...


I don't think so - sugar is sugar. Just calibrate to zero, then use the meter. It should be very close.
I use the same thing - much quicker (and more efficient) than a cylinder and hygrometer - wastes wort.

This is the same instrument used to calculate percentage sugar in fruit (oranges from what I've read).
 
I just use 1.04 and I'm accurate to the point every time I check, good enough for me.

I suggest starting with 1.04 and using the hydrometer too for a few brews. If you are a little high sometimes and a little low sometimes, thats good. If you are high every time, use a slightly larger adjustment, etc.

This is something where you are probably going to have to live with good enough.
 
Brewer3401 said:
I don't think so - sugar is sugar. Just calibrate to zero, then use the meter. It should be very close.
I use the same thing - much quicker (and more efficient) than a cylinder and hygrometer - wastes wort.

This is the same instrument used to calculate percentage sugar in fruit (oranges from what I've read).
Click to expand...

Sugar is sugar, but wort isn't just sugar and water.
 
remilard said:
Sugar is sugar, but wort isn't just sugar and water.
Click to expand...

Right. There is other "stuff" in there too. I think the meter shows refraction based on dissolved sugar.

What I do when I want answers = GOOGLE.

Find reputable sights - there is a lot of garbage on the internet.

Lots of good stuff too.

Always fun finding new things (the real ones)
 
I was reading the instructions on my refractometer when it came Friday It has ATC, but the instructions still say to re=-calibrate when the ambient temp changes more than 5°. So (I don't remember) if that was 5°C, do you guys recalibrate for say winter brewing vs summer brewing or day to day before using?? It says to calibrate it at 68°F but then why would you need to recalibrate it at +-5°?
 
IrregularPulse said:
I was reading the instructions on my refractometer when it came Friday It has ATC, but the instructions still say to re=-calibrate when the ambient temp changes more than 5°. So (I don't remember) if that was 5°C, do you guys recalibrate for say winter brewing vs summer brewing or day to day before using?? It says to calibrate it at 68°F but then why would you need to recalibrate it at +-5°?
Click to expand...

Just take your sample indoors and let sit for 2-3 minutes.

It's such a small sample, it will get to ambient temp. quickly.

I'm in S/E Louisiana, so my temp. variations are not that much.

Take 4-5 drops, bring indoors, then test. You should get a very accurate reading (make sure you calibrate the day of brewing).
 
No need to wait at all. The tiny sample of only a few drops will equalize to the temperature of the instrument almost instantly. The ATC will compensate for variations in the temperature of the instrument. Within the adjustment range of the ATC, ambient air temperature doesn't matter at all. There are limits to what the ATC can handle, but unless you are working in some kind of extreme conditions it will take care of the variations automatically. No need to retreat indoors either.
 
Catt22 said:
No need to wait at all. The tiny sample of only a few drops will equalize to the temperature of the instrument almost instantly. The ATC will compensate for variations in the temperature of the instrument. Within the adjustment range of the ATC, ambient air temperature doesn't matter at all. There are limits to what the ATC can handle, but unless you are working in some kind of extreme conditions it will take care of the variations automatically. No need to retreat indoors either.
Click to expand...

Good thoughts - since the sample is so small, it does not make that much of a difference.
 
A "sugar" refractometer is made to measure sugars, but IS affected by other substances in the wort, which is the reason for the correction factor in the first place. Just like a hydrometer that WE use to measure sugar via SG, is affected by more than just sugar in the solution.

A wine/beer/fruit refractometer will be affected by other solids in the "water". There is no way that the refract. can tell the difference between sugar and other substances that affect light refraction.
 
remilard said:
Sugar is sugar, but wort isn't just sugar and water.
Click to expand...

Exactly Remmy... which is exactly the explaination given in all brewing software that allows for the correction factor to be entered so that the software always applies it for you.
 
Brewer3401 said:
Right. There is other "stuff" in there too. I think the meter shows refraction based on dissolved sugar.

What I do when I want answers = GOOGLE.

Find reputable sights - there is a lot of garbage on the internet.

Lots of good stuff too.

Always fun finding new things (the real ones)
Click to expand...

Brewing software applications actually tell you to determine the correction factor, because these refractometers do NOT see only sugar. They also go on to tell you that this value will be based on individual systems and processes. In the "defaults" setup of brewing software applications you can enter this correction factor so that the software will apply it to the values that you input into the program.

I love google and all, but honestly I trust the software manufacturers as this is thier livelihood.

BeerSmith
ProMash etc... all tell you to use a correction factor, I trust them as I have heard this from other brewers as well. Here is a thread on the topic.
https://www.homebrewtalk.com/f84/be...sers-whats-your-brix-correction-factor-87922/
 

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