Sartorius YDK04 Betriebsanleitung Seite 11

Adhesion of the Liquid to the Wire
Whenimmersingthesample holder inthe
buoyancyliquid,liquidcreepsupthewire
becauseofadhesionforcesandcreatesa
fewadditionalmilligramsofweight�
Sincethesample holder isinthe
buoyancymediumbothwhenweighingin
airandwhenweighinginliquid,andthe
balanceistaredatthebeginningofeach
measurement,theinfluenceoftheliquid
meniscuscanbeignored�
Inordertoreducethesurfacetensionand
thefrictionoftheliquidonthewire,
aroundthreedropsofasurfactant(Mirasol
Antistaticoraconventionaldetergent)are
addedtothevessel'sdistilledwater
contents�
Withthebuoyancyliquidcreepingupthe
wire,theweightvaluemaystillslowly
changeafterthe"g"hasappeared�

Forthisreason,theweightvalueshouldbe
readassoonasthe"g"appears�
Air Bubbles
Themeasurementerrorswhichoccuras
aresultofairbubblesstickingtothe
samplecanbeevaluatedasfollows:Ifthe
airbubblehasadiameterof0�5mm,this
willproduceanadditionalbuoyancyofless
than0�1mgwhenweighinginwater�Ifthe
airbubblehasadiameterof1mm,the
additionalbuoyancywillbearound0�5mg,
andifthediameterisaround2mm,
roughly4�2mg�Itisthereforeimperative
thatlargerairbubblesaretakenoffwith
afinebrushorsimilar�
Moisturecanalsobeaddedinadvancein
aseparatecontainer�
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