switchedto drainto preventover-filling. The tankover-flow provided for
emergencies shouldnot be used.
Cleaning the recovery tanks
The recovery tanks must be cleaned occasionally to remove any micro-
organisms.Thisis doneby emptyingthe tankand connecting it to the cleaning
system. Freshly made-upcleaningsolutionsat the required concentrationsare
used,supplied in small amountsvia the dosingunit.
Freshwatersupply
Freshwatershouldbe supplied fromadequate ring watermains.The connec-
tionsbetweenthe systemand the mainsshould be leak-proof,usingmixproof
valves (double-seat valves)or a low-volume buffertank. If the capacity of the
watermainsis insufficient,the rinsing operationsof the CIP systemshouldbe
designedto be suppliedfroma watercollection vesselbetweenthe systemand
the mains.Freshwatermustnot introduce microbiological contaminationto the
system, and a ringmainis saferin this respect, becausecontinuous water
exchange takesplace.
Freshwateris oftenstoredoverlongperiodsof timein large-volume buffer
tanks, and preventionof microbiologicalcontaminationunderthesecircum-
stancesrequires expensive measures suchas aerationvia sterilefiltersor dosing
withchlorinedioxide.
Insulation
The vesselusedto recover hot cleaning mediamustbe sufficientlyinsulated,at
least aroundthe bottom and the shell.Hot cleaning mediashould be circulated
oncea day for cleaning and to prevent excessive coolingof the CIP recovery
tank. Usinga suitable insulation and circulatinghot cleaning solutionat least
oncea day reducesthe heat energyinputbecause onlythe plantelementsneedto
be heated.Heatloss fromthe circulating cleaningagents can be minimized by
insulatingthe pipes.
Returnwatertanks
Return watertanks must havethe correctcapacity for the entirecleaningsystem.
If the returntankis too small,it will overflowcontinuously, increasing wastage
ratesand mainswaterusage.
27.4.3 Designof CIPplants
The requirementsfor hygieneplacedon a cleaningsystemare the sameas thosefor
a productionsystem.Contaminationfrommicroorganismsfroman inadequately
designedCIP plantwill enterthe productionsystemand contaminatethe product.
Preventingwaterhammer
Water hammeroccurs when liquidis suspendedin the pipesystem, resulting in
evaporationand the condensationof steam. Thisphenomenonoccurstypically if
442 Handbookof hygiene controlin the foodindustry