Terms related to gravity

Specific gravity

Specific force is the arrangement of the body of a sample to the body of water. The arrangement depends on the temperature and burden of both the sample and water. The burden is consistently advised (in brewing) to be 1 atmosphere (1013.25 hPa) and the temperature is usually 20°C for both sample and baptize but in some locations of the apple altered temperatures may be acclimated and there are hydrometers awash calibrated to, for example, 60°F. It is important, area any about-face to °P is involved, that the able brace of temperatures be acclimated for the about-face table or blueprint getting employed. The accepted ASBC table is (20°C/20°C) acceptation that the body is abstinent at 20°C and referenced to the body of baptize at 20°C (0.998203 g/cc). Mathematically

SG_\text{true} = {\rho_\text{sample} \over \rho_\text{water}}

This blueprint gives the accurate specific force i.e. based on densities. Brewers cannot (unless application a U-tube meter) admeasurement body anon and so accept to use a hydrometer, whose axis is bathed in air, or pycnometer weighings which are aswell done in air. Hydrometer readings and the arrangement of pycnometer weights are afflicted by air (see commodity Specific Force for details) and are alleged "apparent" readings. Accurate readings are calmly acquired from credible readings by

SG_\text{true} = SG_\text{apparent} - {\rho_\text{air} \over \rho_\text{water} }(SG_\text{apparent}-1)

However, the ASBC table uses credible specific gravities, so abounding cyberbanking body meters will aftermath the actual °P numbers automatically.

edit Original Force (OG); Original Extract (OE)

The Original Force is the specific force abstinent afore fermentation. From it the analyst can compute the Original Extract which is the accumulation (grams) of amoroso in 100 grams of wort (°P) by use of the Plato scale. The attribute p will denote OE in the formulas which follow.

edit Final Force (FG); Credible Extract (AE)

The Final Force is the specific force abstinent at the achievement of fermentation. The Credible Extract, denoted m, is the °P acquired by inserting the FG into the formulas or tables in the Plato article. The use of "apparent" actuality is not to be abashed with the use of that appellation to call specific force readings which accept not been adapted for the furnishings of air.