Cheap refractometers

Discussion in 'Ebay & Other Limited Offers' started by BeerCat, Dec 21, 2017.

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  1. Dec 30, 2017 #41

    nigelnorris

    nigelnorris

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    I've just had accepted a £2.50 offer for a digital ph meter from the same seller. Doesn't come with batteries which makes it a bit less cheap but I have some kicking around anyway. If you've not looked he has other stuff, for example I also bid for an STC-1000 but he's sold out of them for now.
     
  2. Dec 30, 2017 #42

    Zakrabbit

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    Balls! Paid £4.48 for mine! :lol:

    What was the item number?

    Mine (a T1H7) came with batteries, which I didnt expect. Seems accurate but im waiting on a pack of buffer to test it properly.

    The only thing i'd say about the pH meters is not to return your test sample to your brew!
     
  3. Dec 30, 2017 #43

    nigelnorris

    nigelnorris

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    It's this one.

    Test sample? Surely you just dunk the thing into your brew as you go along?
     
  4. Dec 30, 2017 #44

    Zakrabbit

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    I wouldnt with a pH meter. I dont know what the electrodes on these are made from, but lab ones ive used have had some pretty nasty salts as electrodes! Lead salts etc

    The reference electrodes in these might be silver chloride, but i doubt the manufacturer will tell me

    But you only need enough sample to cover the electrodes, in a suitably sized glass probably 10-20ml or so, certainly less than a trial jar full. The amount sucked up by a wine thief, or a large pipette should be enough
     
  5. Dec 30, 2017 #45

    MmmBeer

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    I received my refractometer today. Didn't get round to calibrating, but tried it against my hydrometer when bottling my Plinian Legacy 5 l extract kit. The refractometer indicated 1.015, compared to the hydrometer's 1.012. I'll get some deionised water before I make my next brew, as its a lot less faff to use than the hydrometer.
     
  6. Dec 30, 2017 #46

    Honk

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    Is tap water not going to pretty close to deionised water anyway? If its good enough to check a hydrometer is at 1.000 at 20c then why not a refractometer?
     
  7. Dec 31, 2017 #47

    Zakrabbit

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    It'll depend on how 'hard' your water is, and whether the dissolved salts have much of an affect on the refractive index - a refractometer works by measuring the extent to which the sample changes the angle of refraction (bending) of linear polarized light through a prism, entirely different to how a hydrometer works

    But its unlikely to be much of an effect, That said, you dont need deionised water, just distilled water, and thats a 30sec job to make enough at the same time as making a cup of tea

    The amount of distilled water you can make just by holding a cold glass over the spout of your kettle while it boils is about 10x what you require to calibrate - so just calibrate it at same time as making a cuppa or pot-noodle :thumb:
     
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  8. Dec 31, 2017 #48

    Zakrabbit

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    Remember as well, that the refractometer is for measuring the sugar content, the dissolved sugar molecules having a high refractive index. Its not intended to measure alcohol content.

    A hydrometer on the other hand measures density of solution in relation to pure water (1.000) and doesnt care what the solute is, as alcohol is less dense than water this leads to high alcohol solutions showing a lower density. In alcohol containing solutions, I wouldnt expect the hydrometer and refractometer readings to match - only in a 'pure' sugar solution

    That said, take a look at the 'liquids' table here https://en.wikipedia.org/wiki/List_of_refractive_indices you'll see that pure ethanol has an RI similar to that of sugar solutions. Its likely that the difference in reading between refractometer and hydrometer in a finished/near finished brew wont be remarkable

    Refractive Index (n) solution at 589.3nm =

    0%
    Ethanol - 1.333
    Sucrose - 1.333

    10%
    Ethanol - 1.3395
    Sucrose - 1.3478

    20%
    Ethanol - 1.3469
    Sucrose - 1.3639

    So, a 10%Brix pure sugar solution would read very similar to a 20% pure alcohol solution. Since a finished brew is a mixture of alcohol, sugars, plus many other substances, I really dont think the readings between refractometer and hydrometer will be too far apart. But, if you do intend to use the refractometer on completed brews, it would be worth using the same sample of brew with each device, and making a note of the 'error' factor, so you can correct between the two

    This website explains how refractometers work http://www.refractometer.pl/
    The 'datasheets' section has the tables for ethanol and sucrose solutions I used above
     
    Last edited: Dec 31, 2017
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  9. Jan 2, 2018 #49

    stevic

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    Tried mine out yesterday, an excellent bit of kit. By the way, did anyone else receive a set of battery operated fairy lights along with the refractormeter or did they mix my order up?
     
  10. Jan 2, 2018 #50

    nigelnorris

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    Same here, once calibrated mine agreed with the hydrometer all the way.

    No lights here, but I got one of the £2.50 ones so can't read much into that.
     
  11. Jan 2, 2018 #51

    terrym

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    Cheap refractometers from the 'ilivingdeals' ebay seller now out of stock. :-(
     
  12. Jan 2, 2018 #52

    BeerCat

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    There were adds for others for £5.99 when i bought mine.
     
  13. Jan 3, 2018 #53

    Zakrabbit

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    Likewise from the seller i used. I suspect, as with many of the chinese sellers, that most of the seller names are in fact the same people, but even if not, it looks like the dispatch was all from the same warehouse in the UK, so they will all go out of stock at the same time once the warehouse is cleared.

    The super low offers accepted, and the quick run out of stock is probably due to space clearing for new stock - possibly a new model (there is a new version being made available) but more likely just for an entirely new product in the warehouse that needs the space.

    So we've probably all grabbed a true bargain!

    I think many far east sellers are now catching on to the idea of using a locally based drop shipper in the target country or region - they ship product in bulk by container. It also avoids many international safety rules - my 'chinese' bought LiPo batteries come by ferry from a drop shipper in Belgium! So I get them almost as quick as by airmail, which they are banned from!
     
  14. Jan 4, 2018 #54

    stevey

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    They were out of stock when I first looked. I looked again a couple of days later, and they had some, I bought one and it arrived in a few days.
     
  15. Jan 4, 2018 #55

    terrym

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    All well and good. But they were out of stock from the 'ilivingdeals' supplier (and still are) which was the point of my post, although other suppliers have more of the same but then the cheapest I found was about �£10.
     
  16. Jan 4, 2018 #56

    nigelnorris

    nigelnorris

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    My £2.50 pH meter has just arrived too.
     
  17. Jan 4, 2018 #57

    Drunkula

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    Do a few tests with it and let us know how it goes. I've also ordered one and want to live vicariously. It's got a thermometer, too, yeah? Even if that works I 'll be happy as mine are all knackered.
     
  18. Jan 5, 2018 #58

    nigelnorris

    nigelnorris

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    Alas I'm away until the middle of next week now so it's going to sit unused. As discussed upstream the one I bought doesn't come with batteries so if you have the same one don't forget to order 2 x 2032 button cells.
     
  19. Jan 5, 2018 #59

    Drunkula

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    Okey doke - got a stack of them here from Poundland. Thanks.
     
  20. Jan 5, 2018 #60

    Fictional

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    I did haha. Thought it was wrongly packed
     

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