12 user instructions – KERN & SOHN EMB 500-1BE User Manual
Page 37
EMB-V-BA-e-1422
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12 User Instructions
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To form a reproducible mean value several density measurement are necessary
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Remove fat from solvent-resistant sample / sinker /beaker.
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Regularly clean sample dishes/ sinker/beaker, do not touch immersed part with
your hands
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Dry sample/ sinker/pincers after each measurement.
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Adjust sample size to sample dish (ideal sample size > 5 g).
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Only use distilled water.
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When immersing for the first time, lightly shake sample dishes and sinker, in order
to Dissolve air bubbles.
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Always ensure that, when re-immersing into the liquid no additional bubbles
adhere; it is better to use pincers to place the sample.
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Remove firmly adherent air bubbles with a fine brush or a similar tool.
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To avoid adherent air bubbles smoothen samples with rough surface.
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Take care that no water drips onto the upper sample dish when weighing with the
help of tweezers.
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In order to reduce the surface tension of water and the friction of the liquid on the
wire, add three drops of a common detergent (washing-up liquid) to the aid liquid
(density modification of dest. water occurring due to the addition of tensides can
be ignored).
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Oval samples can be held more easily with pincers when you cut grooves into
them.
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The density of porous solids may only be determined approximately. Buoyancy
errors occur when not all the air is eliminated from the pores during immersion in
the aid fluid.
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To avoid great vibrations of the balance, place sample carefully.
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Avoid static charge, e. g. dry sinker with cotton cloth only.
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If the density of your solid only deviates slightly from that of distilled water,
ethanol may be used as aid liquid. However, check beforehand whether the
sample is solvent-proof. In addition you must observe the applicable safety
regulations when working with ethanol.
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To avoid corrosion, don't leave the density kit immersed in liquid for a long time.