KERN & SOHN EMB 500-1BE - Manual (Page 37)

EMB-V-BA-e-1422 37
12 User Instructions
• To form a reproducible mean value several density measurement are necessary
• Remove fat from solvent-resistant sample / sinker /beaker.
• Regularly clean sample dishes/ sinker/beaker, do not touch immersed part with
your hands
• Dry sample/ sinker/pincers after each measurement.
• Adjust sample size to sample dish (ideal sample size > 5 g).
• Only use distilled water.
• When immersing for the first time, lightly shake sample dishes and sinker, in order
to Dissolve air bubbles.
• Always ensure that, when re-immersing into the liquid no additional bubbles
adhere; it is better to use pincers to place the sample.
• Remove firmly adherent air bubbles with a fine brush or a similar tool.
• To avoid adherent air bubbles smoothen samples with rough surface.
• Take care that no water drips onto the upper sample dish when weighing with the
help of tweezers.
• 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).
• Oval samples can be held more easily with pincers when you cut grooves into
them.
• 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.
• To avoid great vibrations of the balance, place sample carefully.
• Avoid static charge, e. g. dry sinker with cotton cloth only.
• 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.
• To avoid corrosion, don't leave the density kit immersed in liquid for a long time.