∑ Supply pumpdefects (impeller,motor,leaks): resultsfromthe formationof
deposits due to insufficientpressureand flowvelocity.
∑ Return pump defectiveor insufficient feed: results in the formationof
deposits at the bottomof the tankbecause too much liquidcollects at the
bottomand thereis insufficientturbulenceto prevent depositbuild-up.
∑ Turbulenceat the tankoutlet,returnpumpdrawsair: similar problem to the
above.Withnon-self-priming returnpumps, recirculationis interrupted.
∑ Leaksat pipeconnections:pumpdelivery collapses,foamformsand flow
rate is reduced.
Corrosion
Materialsfor the production and CIP systems must be carefullyselectedto allow
for the corrosiveeffectsof the products, cleaningagentsand disinfectants.The
chemical behaviourof industrial waterwithrespect to corrosionunder operating
conditions must be examined. The corrosive effects of detergents and
disinfectants should be specifiedby the manufacturers.
27.4 ImprovingCIP systems
27.4.1 Coldtankand hot pipecleaning
Figure 27.7is a schematic diagramof an optimizedCIP systemfor cleaning
tanks and production systems. Single-use cleaningtanksare recommended for
coldtank and hot pipecleaning in the brewery and beverageindustry, in
combinationwithrecoverablecleaning for the pipe and productionsystems
(satellite cleaning).Recoverablecleaninghas beendemonstratedto haveclear
advantagesoversingle-usecleaningwithregardto chemicalconsumption and
effluentrates. However,single-use cleaningis more suitablefor coldtank
cleaningbecause it avoidsthe risk of microbiological contaminationthat is
associatedwiththe use of recoveredcleaningsolutions.
Single-usesystem
The single-useCIPsystemshould be located closeto the tankgroupto be
cleaned,in orderto minimize consumption of cleaning solutionsand reduce
effluentrates.Locatingthe cleaning systemnearthe tanksreduces circulation
volumes because the inlet and outletpathsfor the cleaningmedia are short,and
losses fromintermediaterinsing stepsand flush-outsare reduced.
The CIP circulationpumpand the CIP returnpumpmust be tunedto each
other at the supply pumpby controllingtheirspeeds (frequency adjustment). If
the flowrates are not coordinated,the buffertankbetween the pumpswill be
overfilledand/oremptied continuously.
The levelof the sumpproduced by internal cleaning of the tankshouldbe
keptas low as possible and shouldpulsate (fluctuate) duringthe cleaning
operation.The sumpinsidethe tankshould at leastcoverthe tankoutletand
prevent eddying at the outlet.Changingthe heightof the pulsesprevents a layer
438 Handbookof hygiene controlin the foodindustry