pressure untilit stopsconveying, and thereforepowerconsumptiondecreases. A
self-primingpumpcannotbe throttledbackin this way,or can be throttled only
veryslightly,and so power consumption increases.
Owing to the small clearancebetween impellerand housing,the periphery
pumpis verysensitive to soiling. If dirt ingressis likely,dirt trapsshould be
provided on the suctionside.27.3.9 Designconsiderationsfor CIPsystems
A numberof factors must be takeninto account when designingCIP systems to
ensure that theyare bothtechnically and commerciallysuitable.A majorfactor
is the production process that the cleaningsystemwill be associated with.Plant
downtimesare important,becausethey indicate when and for how longcleaning
can takeplace.The numberof shiftsrunningalsoaffects timingof cleaning
operations,as doesidentifyingwhichareascan be cleanedsimultaneously.
Whenthe systemis highlycomplex,a production and equipmentallocationplan
is useful. Customerrequirementsand specificationsmustalso be considered.CIP circuit groups
CIP circuits can be groupedwhereone or moreof the followingfactorsare
similar in the areasto be cleaned:
∑ production conditions;
∑ typeand degreeof soiling;
∑ conditions required for cleaning solution (composition, concentration,
temperatureand reactiontime);
∑ flowrates(avoidextremechangesin nominalwidths); and
∑ timeallowed for cleaning.
Matchingflowvelocity in grouped CIP circuits is important. Figure27.6shows
the influenceof differentnominalwidths on flowvelocity and pressuredrop.
Fig. 27.6 Influenceof differentnominalwidthson flowvelocityand pressuredrop.436 Handbookof hygiene controlin the foodindustry