system). Thepulses travela fixeddistanceto a receiverthat convertssonar
energyto electricenergy. The timethe pulsetravelsbetween emitter and
receiver is measuredand the sonarvelocitycalculated fromthe fixeddistance
between emitter and receiver and the lapsed time.
Alsothis physical property of a material can be automaticallymeasuredeven
within-lineprobes and mayserve in combination withone or more of the other
methodsdescribedas a rapid and easymeansof identification for product
concentrates.
Tracers
Someproducts maycontain tracers that can be detected witha dedicated
method.Thisis of coursean indirect methodthat can onlybe usedfor the
identificationof a producttype, but not as a qualitycontrol measurebecause
onlythe presenceof the tracercan be proven but no physicalproperty of the
product.
Checking other product qualities
It is evenpossibleto identifycompoundsof cleaners withsimple tests,e.g. using
test strips similarto pH-paper.Available chlorineand peroxides,as wellas
QACscan be identifiedwithsuchtests,and when pre-diluted undercontrolled
conditions, the testsmaybe quantitative. However, quality control of incoming
goodsmightbe moreusefulif proper concentrationsof the mainingredients in
the hygieneproducts can be determined.
The followingchemicalingredients are commonand relativelyeasyto deter-
mine:totalalkalinity, totalacidity,available chlorine,totalperoxides,hydrogen
peroxide and peroxyacetic acid, anionic surfactants and cationicsurfactants.In
addition, with relatively inexpensive photometricequipment, thereare quicktests
for phosphatesand non-ionic surfactants. These simple methodspermit a suffi-
cientlevel of identification and quality controlfor incominghygieneproducts.
Accordingto a previousstatementaboutthe technicalgradeof the discussed
products, it is alwaysessentialto set and agreeuponappropriaterangeswiththe
product supplier ratherthandiscretevalues.The tested samplehas to be within
the rangeof agreed specifications.
Conclusion
The methodsdescribedmaywellserve as product identifiers to avoid a road
tankerfillingthe wrongholding tank,but also to measureproduct propertiesfor
qualitytestingor evento identifyproducts fromold stocks withmissing or
damagedlabelling.
39.3.2 Automaticcontrol of preparing use solutions
In automaticcleaningsystems, it is veryunlikelythat productsare mistaken,
especially when the concentrates are taken from bulk storage tanks with
satisfactory control of incominggoods.Herethe humanfactoris still the highest
risk whenconnecting smallcontainers suchas jerrycans,drumsor transi-tanks
Traceabilityof disinfectants and sanitisers 679