system, whichgivesa measureof concentration.Conductivityprobes indicate
that rinsing has beensuccessfuloncethe conductivityof the rinsewaterfalls
belowa specifiedthreshold.
The measuringelectrodemustbe temperature-compensated to allowfor the
effectsof temperature changeson concentration, and must be resistant to
`ageing', deteriorationcaused by chemicalchanges overtime.The electrodes
mustbe checked regularlyto ensurethat theyare free of soil deposits. They
shouldnot be installedwherethereis a heavydirt load, as this tends to increase
salt concentrationsand thereforeconductivity,whichwill be assumed to indicate
highdetergent concentration.The measuring electrodemust alsobe installed
wherethereis sufficient turbulence,because low turbulence will resultin lower
measurements.
Figure27.5givesthe conductivities of variouscleaningsystemfluids, and
showsthe influence of temperatureon conductivity.
27.3.4 Componentsusedfor cleaninginsidetanks
Sprayballs
Sprayballscomein severaldifferenttypes.Theymustgenerate 30±50litres of
liquidper minuteper metreof the tankcircumferenceto maintain a continuous
liquidfilmon the tankwall.
Rotating jet cleaner
Rotating jet cleaners use differentsizes of fan-shapednozzles, and rotateslowly
insidethe tank.The liquid film runs downthe tank wall in spirals,whichhas the
effectof a pulse±pauseoperation.Rotating jets can generate highspecificliquid
impacton the tankwallat a low totalconsumption.
Orbitalcleaner
Different typesof orbital cleanersoperateat high,medium or low pressures,and
come withor without an external motor. They providenarrow planetary
scanning of interiorsurfacesof tanks and large containers.
27.3.5 Tanksfor collecting cleaningsolutions
Tanksfor cleaningsolutions and disinfectants
These tanks store cleaning solutions for all CIP circuits that operate
simultaneously.
Fresh-water tank
The fresh-water tankseparates the CIP system physicallyfromthe watermains.
Fresh-watertanksmusthavethe capacityto supplyall CIP circuitsthat mightbe
runningat the same time,withtheirwaterlevels falling to not less than one-third
full. The freshwaterin the tankmust be usedas soonas possibleto reducethe
risk of contamination.
Improving cleaning-in-place (CIP) 433