Here, the sample volume V (pr) corresponds to the liquid volume V (fl). The sample
volume is determined by measuring the buoyancy. Hence, it is:
V (pr) = V (fl)
or
W (a) – W (fl) π · h · D
2
=
ρ (fl) 4
4 · [W (a) – W (fl)]
Therefore, h =
ρ (fl) · π · D
2
The buoyancy “A” caused by the immersed wires is:
π – d
2
A = 2 · · h · ρ (fl)
4
When “h” is used:
2 · π · d
2
· 4 · [W (a) – W (fl)] · ρ (fl)
A =
4 · ρ (fl) · π · D
2
d
2
A = 2 · · [W (a) – W (fl)]
D
2
To allow for the buoyancy of the wires, subtract the buoyancy “A” caused by the
immersed wires from the buoyancy determined for the sample: G = W (a) – W (fl).
The corrected buoyancy “A (corr)” to use in this calculation is then: G – “A.”
d
2
A (corr) = [W (a) – W (fl)] – 2 · · [W (a) – W (fl)]
D
2
d
2
A (corr) =
[
1–2·
]
· [W (a) – W (fl)]
D
2
The specific gravity determination kit uses the large-volume beaker (76 mm Ø)
and an immersing device with 2 wires (0.7 mm diameter) for the determination of
the specific gravity of solids.
When the values d = 0.7 mm and D = 76 mm are plugged in the equation, the
correction factor is:
0.7
2
1 – 2 · = 0.99983
76
2
When using devices with other dimensions, the correction factor must
be recalculated.
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