There may be efffects, but I think they would be much smaller that 1 and 2 above. You can Google "air bouyancy" for techniques, formulas.ģ) Temperature: I don't know. The bouyancy effect of air on 1 L of sample is around 1 g, so this must be considered for density more precise than 0.001 kg/L. Particularly table 109 is in vacuo, but has typos, table 114 is apparent hence they are different. Be sure which you want agrees with which you are using. The NBS tables were published both for "in vacuo" and "apparent" data. Commercial weighing generally ignores it. High precision lab work considers this effect and reduces to "in vacuo" weight. On a balance, this affects both the weights and the sample. Use modern tables for density of water at 4 and 20 ☌Ģ) Just like water, air exerts a bouyancy effect on everything immersed in it (but much smaller). The SGs in the NBS tables should be unaffected, but the densities are obsolete. The modern definition of 1 dm³ gives a different absolute density. A few cautions.ġ) The liter had a difference definition in 1942 (1901-1960 really), 1 kg of water at 4 ☌. I put what little I could figure out in it. I'm grateful for any help I can get.We have a thread here on Brix. How are these factors calculated in the first place?ģ) Is the effect of redefinition of 0 'C in 1948 (IPTS-48), 1968 (IPTS-68) and 1990 (ITS-90) significant when converting older SG tables (probably based on experimental data with temp measurements using older temp scales) to metric density (SI)? This seems to suit the data well, but then I saw many other similar factors on the internet (none the same). Gupta (Practical density measurement and hydrometry,2002) multiplying SG 20/4 by 0.999975 produces metric density. Before I use tables/formula giving the metric density of sucrose solutions produced by an industry body (ICUMSA, 1998), I want to verify these values using brix tables published by NBS in 1942.ġ) What are the factors or equations to covert the following to metric density?Ģ) According to S.V.
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