Mettler Toledo Excellence XP Instrucciones De Manejo página 13

Air bubbles
With poorly wetting liquids (e.g. water without wetting agent), it is possible that air bubbles remain
adhered to the immersed parts (solid, sinker, holder) and influence the result owing to their buoyancy.
A bubble with a diameter of 1 mm causes a buoyancy of 0.5 mg, whereas one of diameter 2 mm
results in a buoyancy as high as 4 mg. To avoid air bubbles, we advise the following precautionary
measures:
– Degrease solvent-resistant solids
– Clean holders and sinker at regular intervals, never touched parts which are immersed with your
hand
– Gently shake holders and sinker on first-time immersion to dislodge any air bubbles
– Remove tenaciously adhering air bubbles with a fine brush
– Use enclosed or commercial wetting agent or organic liquids (the density change experienced by
distilled water on the addition of wetting agent can be neglected).
Porosity of the solid
When solid bodies are immersed in a liquid, usually not all the air in the pores is displaced. This leads
to buoyancy errors and thus the density of porous bodies can only be determined approximately.
Density determination kit for Excellence XP/XS analytical balances
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