Withless sophistication,sucha test can also be donewithpH-paper.Testing
withpH-papermayalsobe usedin caseof spillsas an informative test to
determinewhether a product is alkaline, neutralor acidic.
Measuringthe conductivity
Whatis true for pH measuring appliesalso for conductivitymeasuring:onlyin
diluted solutions can correct valuesbe obtained.At higher concentration the
degree of dissociation and ion mobility decreases, thus altering the
proportionalitybetween concentrationand conductivity.Conductivityis only
a measure of the physical property of conducting electricalcurrentbut doesnot
giveany other information aboutthe characterof a product when usedas a
single method. Carefully adapted, this method might be used for the
identification of concentrates in combinationwitha secondmethod.
CombiningpH and conductivity
Twodifferentproductscan easilyhavethe same conductivitybut still havea
verydifferent composition.Findingtwo concentrates in one placewiththe same
pH and conductivity is more unlikely. Therefore, a combinationof both
methodswill dramatically improve reliability as a rapidand simple product
identification method.
Refractiveindices
This is a veryfast and simple methodwitha highlydiscriminatingcharacter;
therefore it is importantto definea range,not a standardvalue.Deviations that
occurdue to the technical gradeof the products question will be detectedand
might causeuncertainties.Whenusedas a thirdparameteralong withpH and
conductivitythe identificationis nearly100%safe.
The aforementioned methodsare availableas automated on-linesystems as
wellas hand-heldmanualprocedures or laboratoryprocedures. The required
time, evenfor all threemethods together,is less than10 minutes, including
evaluation.Alone or in any combination,theycan be usedto safeguard bulk
tankreceptionsor as simple but highlyreliable quality check, i.e. a checkof
specification± quality is heremoreusedin a senseof propertiesto ensure the
material really is what it should be, and not in a senseof goodor bad quality.
Density
Measuringthe density of a product is also a relatively simpleand fast methodto
collect information.In combination with conductivityand pH it is a verysecure
methodto identifya product veryprecisely.If not usingthe most accurate
methodsand evaluating the thirdfigureafterthe decimal point,measuringa
product's densitycan be morepracticalthanthe refraction index.
Measuringthe velocityof soundin a product
This is doneby employingpiezo-electronicelements.A disk-shapedemitter is
forced intofast oscillationsthusemittingshortclubbedpulses (likea radar
678 Handbookof hygiene controlin the foodindustry