Refractometer Help Pls (Brine Salinity V Str ° and density

[David7019]

Good morning,

First time poster here, so please be gentle

Historically we have been using a Glass hydrometer (brineometer) it measures from 0-100% Salt by weight so at 100% this would = around 26.4 % saturated.

Now they keep getting dropped and broken and due to the fact they are made of glass and mercury i think? as the bouyency part its not ideal...

 

So i have bought a Refractometer from Atago it can (im told by Atago) measure Density of saline at 20°c 1.000 to 1.070 with a 20/20 symbol at the bottom (which i dont understand what this is).

Anyways If i take a brine strength reading at 36° this = around 9.502% salt by weight or 1.070 which appears to be the max of the refractometer but if i take a sample of the solution and use it in the Refractometer it shows a reading of around 90‰ or parts per million with a density reading of 1.068

Now this just has me confused a little this isnt close to fully saturated of 26.4% by weight.... one of my solutions can have a str ° reading of 60-70 which according to my calculation would be 15.83 ish % by weight density 1.118 which goes beyond 100‰ unless it has something to do with this D20/D20 symbol? or the unit i have been sold is not accurate enough? even though they told me it was suitable...

I may even be over thinking this i dont know but i do need some smarter person to educate me or point me straight.

For your information i atta ch a table to demonstrate what i mean. i have used 35L water adding 250g and taking readings with both the brinometer for Str° and then the refractometer for salinity‰

at around 36° strengh i appear to reach the limit of the Refractometer......

 

Excel.Docxlsx.xlsx

 

Kind regards

Dave

Excel.Docxlsx.xlsx

Excel.Docxlsx.xlsx