Sartorius YDK01 Mode D'emploi page 25

Allowance Factors
You must allow for the following
when determining the specific gravity
of solids:
– the air buoyancy that affects the
sample weighed in air
where ρ (a) = 0.0012 g/cm
of air under standard conditions
(temperature 20°C, pressure 101.325 kPa);
which results in the following:
W (a) · [r (fl) – ρ (a)]
ρ =
W (a) – W (fl)
– the immersion of the wires of
the sample holder or sieve
When using this specific gravity
determination kit, you must multiply
the buoyancy G = [W (a) – W (fl)] by
the factor 0.99983 (Corr). Therefore:
W (a) · [ρ (fl) – ρ (a)]
ρ =
[W (a) – W (fl)] · Corr
This factor allows for the buoyancy
of the wires which are submerged deeper
when the sample is in the sample holder.
How this allowance factor is derived:
The buoyancy caused by the submerged
wires depends on the height "h" by which
the liquid rises when the sample is
immersed.
Here, the sample volume V (pr) corresponds
3
= density to the liquid volume V (fl). The sample
volume is determined by measuring the
buoyancy. Hence, it is:
V (pr) = V (fl)
+ ρ (a)
or
W (a) – W (fl)
Therefore, h =
+ ρ (a)
The buoyancy "A" caused by the immersed
wires is:
A = 2 ·
When "h" is used:
ρ =
A = 2 ·
2
π · h · D
=
ρ (fl) 4
4 · [W (a) – W (fl)]
ρ (fl) · π · D
2
π – d
· h · ρ (fl)
4
2
2 · π · d · 4 · [W (a) – W (fl)] · ρ (fl)
4 · ρ (fl) · π · D
2
d
· [W (a) – W (fl)]
2
D
2
2
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