Returnwatertank
Thistankcollectsthe waterfrom the intermediate and finalrinsingsteps,
holdingit readyfor the next pre-rinse.The tankmust be largeenoughto cope
withthe volumeof waterbeing usedin the rinsingstepsthat supply it.
27.3.6 Tanksfor storingdetergentconcentrates
Tanksusedfor storing detergent concentrates mustbe type-tested,and must be
installed and maintainedonlyby an approvedexpert company.The tanks must
be closed,shouldnot be operated underpressure,and shouldbe protected
againstmechanical damageand freezing.Storage tanks mustbe installedin a
collecting pan that can holdthe entirecontents of the tank.Theyshouldhave
separate fillingpipesfor eachproduct, and when concentratesare supplied from
a roadtanker,it mustbe ensured that the hoseconnectionscannotbe mixedup.
Tanksshould be equipped withlevelindicators and devicesto protectagainst
overfilling, includingautomatic interruption of the fillingprocess if there is a
risk of overfilling.The internal diameter of the ventingand overfilling pipes
mustbe at least20%largerthanthe fillingpipe.The fillingpipe musthavea
shut-off valveand a non-returnvalve, and ventingpipesmustbe connected to
the atmosphere ± gas and steamexhaust in the storage area must be avoided.It is
also importantto ensurethat no unwantedchemicalreactionsoccurin grouped
ventingpipes.
Componentsfor heatingthe tankcontentsmust be protectedagainstdry
runningand should havetemperaturelimitswitches.All the relevantlawsand
regulations for installing,filling and using thesestoragetanks mustbe takeninto
account.
27.3.7 Non-self-priming centrifugalsupplypumps
The pressureand the flowrate in a pipesystem are not produced by the pump,
but by the resistancein the systemitself,so the pumpmusthavethe capacity to
supplythe entiresystemand copewithall cleaning tasks.In practice,a single
pumpis generally usedto supplyseveral differentCIP circuits, whichall have
theirownsystemcharacteristics. Thepumpsmust therefore be ratedfor the
maximum required flow rate and deliverypressure,and mustthen be adjustedto
the other circuitsby means of throttlingin the pipe systemor speedadjustments
via frequency control.
27.3.8 Self-primingcentrifugalpumpsfor CIPreturn, usedfor tank
cleaning
Thesepumps are gas-conveying peripherypumps,and havevery goodsuction
capacity. In contrast to non-self-primingpumps, centrifugalpumpscontinue
operating evenif the liquidbeingsucked out of the tankcontains air or other
gaseous media.A non-self-priming pumpcan be throttledbackby the dropin
Improving cleaning-in-place (CIP) 435