Sg And Temp

[kfarrell]

Heyas, I'm a newb *8)

So I used to read Hydrometers for a living, (petrochemicals) so I know in some cases temp can make a big difference to the reading. So as such we had a chart that converted the hydro reading at temprature to 15C.

So here's my question. When I add cold water to my mix the temp is about 27C, my final reading is more likely to be at 21C, That's a big difference in temp. When calculating Acloholic Content, should there be a way to convert both hydro readings to 15C, is there a chart or calculator that would help here?

 

[pint of lager]

Hi Kieran,

You are after what is commonly called in brewing circles a hydrometer correction chart.

Have a read through this thread and download wortgame's link.

 

[Adamt]

Pure water at 15C should be 0.999 on the hydro, at 20C, 0.998 and 25C 0.997.

i.e. between 15C and 25-27C, water volume increases by (1/0.997)/(1/0.999) - 1 = 0.2%

So for your reading at 27C, multiply the density (if SG = 1.050, density = 1050) by 1.002

Doesnt really make much difference at all at those temperatures.

 

[RobboMC]

I'd be trying to reduce the temp of your mix by adding some
pre-refridgerated water, and start your brew at something like 22 deg C.
Then as Adamt says, the odd few degrees don't make any difference.
And with the froth on the surface I seriously doubt anyone can read the hydrometer to within an accuracy of about 0.02 anyway.